CHAPTER FOUR

THE TOOL MAKERS

Man is a toolmaker. The progress of mankind has been marked by the ability to develop better tools. At first, simple tools for hunting, then tools for agriculture and construction, and always the extension of his hunting tools to war making. Finally with the Industrial Revolution, man began to invent mass-production machine tools.

Early man made his tools from materials at hand, sticks, stones, and bones. Later, as he moved upward on the scale of evolution, he began to shape his tools. He sharpened suitable sticks for spears. He shaped stones, especially flint, to make points and sharp edges. Man's first experience with metals was with gold, silver, and copper. These were found in the metallic form as stream nuggets of outcroppings. They were not generally suitable for tools because they were too soft to hold a point or cutting edge, but they were easily worked into intricate jewelry and art objects which were greatly valued by political and religious leaders from earliest times. Later man learned to smelt these metals from their ores, and then to make alloys. The first were alloys of copper and tin, bronze.

Occasionally man found limited amounts of iron in meteorites. Iron was more difficult to hammer into objects, because iron is inherently stronger than copper, silver, and gold. Man, however, had learned that even these soft metals became harder the more they were hammered; and had discovered they could be resoftened by heating. Afterwards they could be worked again, and this process could be repeated as often as necessary. It was but a simple step to work iron while it was still hot; behold, the first blacksmith.

With the passage of time, man learned to reduce small amounts of iron from its ores. This iron was a very primitive material. The early metal makers could not get their furnaces hot enough to melt the resulting mass that collected at the bottom, but like the chunks of meteoritic iron, this mass of part metal, part furnace residue was hammered hot into useful shapes. The iron age, which started about 1200 B.C. in Asia Minor, eventually supplied many of the tools and weapons as it swept across the Western World. The blacksmiths, the men who worked bars of iron into useful products, learned that long heating in a bed of hot charcoal could produce a layer of much harder iron on the surface. If the hot metal was plunged quickly into water, this surface layer could be made extremely hard. These early blacksmiths were in fact forming a layer of steel by absorbing carbon from the burning charcoal.

Man now had his ultimate tool, heat-treated steel. Even though his techniques were very primitive; a sword, knife or spear made in this manner could have been as useful or deadly as any similar object produced today. The finest tools of all were the Damascus swords and Toledo blades of the Western World and the Samurai swords of Japan. These were made by repeated operations of heating in charcoal and hammering out to long pieces that were folded back on themselves. With each operation the two mating surfaces were welded together to eventually form a structure made up of hundreds or even thousands of layers. Thus, the original thin layer of surface steel plus the new layers added with each reheating eventually produced a tool with carbon distributed throughout.

The earliest record of man making steel by melting wrought iron and carbon together is credited to Aristotle who in his wanderings had come in contact with what was known as Wootz Steel from India. Aristotle cited 350 B.C. as the time when Wootz Steel was first made, although some historians believe it may have been made still earlier in China. Wootz Steel was simply man-made iron from a simple, crude smelting furnace which was worked into bars and cut into pieces. These small pieces were placed in clay crucibles to which wood chips were added. After sealing, these crucibles were heated in small furnaces to a fairly high temperature by the use of an air blast from skin bellows. In this manner melting occurred as the iron absorbed carbon from the wood which lowered its melting temperature. Once completely molten, the resulting steel was uniform in carbon. This was man's first truly homogeneous steel.

About the time of the Middle Ages iron making reached the stage of development with larger blowing bellows so that melting could take place in the blast furnace. The Chinese had reached this level of technology centuries earlier. They had invented the double-acting bellows, which made it easier to reach higher temperatures in the furnace. Casting to shape was an old art that had been practiced with the metals and alloys of lower melting temperatures such as copper, silver, gold, lead, and bronze. The huge bronze doors on the Pantheon in Rome were made in this manner over 2000 years ago.

Cast iron, once man had learned to melt it, was unlike any other iron that he had encountered. Cast iron could not be hammered or worked into any other useful form. It was brittle and could not be worked hot or cold or after any treatment with fire. In addition, cast iron frequently failed in service as heavy tools or weapons. Ancient and medieval man had only the art of making iron, a limited amount of steel, and finally, cast iron-- but little technical knowledge or understanding. How his charcoal fire turned iron into steel was a complete technical mystery to him. Any explanations probably rested on the fire itself or, in the case of hardened steel, on the art of quenching (one favorite quenching solution was the urine of a red-headed boy). The few artisans who still practiced high-quality steel making were the sword and knife makers.

Carburized iron, that is iron that was heated in contact with charcoal or other carbonaceous material to produce a surface layer of steel, was manufactured much more efficiently during the Middle Ages by processing a quantity of bars at one time in muffle furnaces. The resulting product was known as blister steel because of the scale formed during the long heating cycle. Blister steel could be hammered into tools, but the thin carburized layer did not lend itself to extensive hot forming or strong, heavy tools To overcome this difficulty, the early steelmaker would forge his carburized bars, cut them into short lengths , stack them, reheat, and forge again. The product of this simple process was called shear steel, and if the process was repeated it was called double shear steel. In this manner the original surface layers of carbon could be distributed through the bar in thin bands to provide a more uniform material (that is, more uniform than just having a thin layer on the surface).

At about the middle of the 18th century a British clockmaker, Benjamin Huntsman, who was looking for a more uniform steel for clock springs, rediscovered the ancient Wootz method of melting small quantities of iron ( blister steel in this instance, which had already been carburized ) in clay pots. His method was further refined years later by the steel maker Mushet who simply added pig-iron to crude sponge-iron. For over 150 years (1740 to 1920) this process was used for making steels for tools. The crucible process, as it was called, was suited for making small batches of high-quality, controlled- chemistry steel, especially for adding the alloying elements that were found to improve tool performance.

The tool steels made in the first 100 years after crucible melting was available were simple iron-carbon alloys. During the 1860's, Robert Mushet was doing practical processing work on adding other metals to tool steel. (His suggestion to Bessemer that he add a small amount of manganese to his steel after blowing air was critical to the success of the Bessemer process). Mushet's studies led him to the discovery (1868) that additions of tungsten and manganese in sufficient amounts caused steel to be extremely hard on cooling in air from a red heat All conventional wisdom said hardening could be done only by rapidly quenching in water. Robert Mushet's discovery of adding alloys to steel to effect the way they could be hardened was a historic milestone in the story of man as a toolmaker. His technical discovery was so little understood, however, that it did not lead to further advances at the time. The company he formed to make his special steel failed. Luckily the steel survived when made by a well established Sheffield crucible steel maker, and it was still the principal tool steel in use as late as the 1890's. Robert Mushet's Special Steel, as it was called, contained 2% carbon, 2.5% manganese and 7% tungsten. It is considered the ancestor of all modern tool steel. It could withstand greater service conditions and required less resharpening with its greater resistance to wear.

The locale of the development of superior steels for tools shifted momentarily to the Jacob Holtzers Steel Company in Loire, France. Henri-aime Brustlein was studying the use of chromium as an alloy in steel. His work is mentioned in the chapter on Alloy Steels. Brustlein's developments of interest for tool steels occurred about 1890 when he became involved in using chromium in the tungsten tool steels of Robert Mushet. He brought samples of his steels to the United States in 1892; and discussed their advantages with the Midvale Steel Company in Philadelphia, Pennsylvania. At this critical time Frederick W. Taylor was conducting studies on production efficiency at Midvale. This was pioneering work on time and motion measurements, and Taylor was to become world famous as the founder of the Efficiency Expert concept. During this period Taylor became interested in time studies on machining metals. Thus he became familiar with the new Brustlein-type tool steels. Later he went to work for the Bethlehem Steel Company where he was again concerned with machining efficiency. Here he proceeded to promote the superiority of the Brustlein tool steels to the practical shop men. The story goes that a carefully controlled demonstration was prepared. It produced considerable embarrassment for Taylor, the educated expert. The new tools made from Brustlein's steels were found to be inferior to the old standard grades, probably because of faulty heat treatment. Taylor, with the help of an experienced Bethlehem metallurgist, Munsel White, undertook a study of the heat treating variables affecting the performance of alloy tool steels. Their results revolutionized the modern tool steel industry.

In the course of their study Taylor and White found that the higher the heating temperature before the steel was cooled, the greater the usefulness and life of the tool. Metals men had known all these years that if steel was heated at too high a temperature it would be ruined, "burnt" as they described it. Taylor and White simply followed the clues provided by their own experimental data. They led them to temperatures almost to the melting range of their steels. Alloy steel tools containing tungsten were so greatly improved if heated to these excessively high temperatures before cooling that they could be operated under conditions so severe the cutting point would glow to a dull red. Later, with some refinement in alloy content, these would be called high-speed steels, and they would be said to possess red hardness.

The discovery of high-speed steels revolutionized the machine tool industry just when America was gearing up for the age of mechanization. These steels were still being made by the crucible melting process, but by 1906 the Sanderson Steel Company of Syracuse, New York installed the first electric arc furnace in the United States for melting tool steels. Other tool steel companies were formed about this time, and electric arc melting was adopted as the preferred method. As the tool steel industry expanded in the early decades of this century, many alloy, tool steel types were invented or imported from England and Europe. These early years saw each steel company with its own brand names, numbers or other special identification for many different grades of steel for a wide variety of applications such as hand tools, cold-forming dies, hot-forming dies, lathe tools, and milling cutters. Many of these steels were higher carbon (for higher strength or hardness) versions of early alloy steels from France, Germany, and England. Secrecy rather than patent coverage and facts was resorted to in making and marketing tool steels. This state of affairs must have been confusing to the customers and users of these steels, it did, however, provide a method of bonding the user to the producer in the belief that he would obtain consistent performance.

Taylor and White did their initial work in 1898, and the results of their new knowledge was demonstrated at the Paris Exposition of 1900. The only presentation on this great achievement was an address by Taylor at the American Society of Mechanical Engineers in 1906. Taylor and White, and their employer realized from the beginning that they had not invented a new steel but rather had developed a breakthrough in alloy steel heat treating. Patents were applied for and obtained on this unique extremely, high temperature (2200 to 2400F) treatment for hardening. The commercial goal of Bethlehem Steel Company was to license manufacturers in using this treatment. The commercial strategy soon disintegrated because many shops simply ignored the patents; and when Bethlehem went to court to enforce its patent, it lost the long, drawn out court battle.

In the meantime improved alloys which would give maximum response to the Taylor and White heat treatment were being tested in many of the advanced industrial countries. A young metallurgist who was active throughout these times was Dr. J. A. Mathews of the Crucible Steel Company. Dr. Mathews reported the results of a survey that he took in 1901 on the common tool steels in use. "Modern High- Speed steels seem to have sprung fairly fully developed from a variety of sources at almost the same time" he wrote. He further stated that he had been unable to show just when the change from the old type of high speed took place. The change from the old type to the new that Mathews is referring to was a rather drastic change in chemistry from the old Mushet steels containing 1.5 to 2.0% carbon, 2.5 to 4% manganese and 7 to 9% tungsten to new steels with 0.6 to 0.8% carbon, 4 to 6% chromium (manganese was no longer used) and 10 to 20% tungsten. Quoting again from Mathews, "It is probable that we shall never know who took the radical steps and made the first low-carbon, high-tungsten, high-speed steel, but immediately following the announcement of the Taylor-White process there was great activity on the part of all tool steel makers in every country to produce a product which would yield maximum results when treated by this process. The courts decided that Messrs. Taylor and White did not make a patentable invention or discovery. The world, however, seemed to differ with this decision and every scientific honor was awarded them for their epoch-making announcement which revolutionized machine shop operation and machine-tool building".

Dr. Mathews was more than just a casual observer on the high-speed steel scene. His patent, granted in January 3, 1905, for the addition of vanadium to high-speed steel was discussed in his own words as follows: "This writer began experimenting with the use of vanadium in 1903, and it is well to bear in mind that at that time vanadium was almost a chemical curiosity. It was worth about $15.00 a pound, and this was some time prior to the formation of the American Vanadium Company which manufactured and sold vanadium in large quantities. So far as the writer is aware, the entire stock of ferrovanadium in the country when these experiments were begun consisted of not over 100 pounds in the hands of two different dealers in New York. We purchased half of the entire stock of each dealer". The experimental work described by Mathews was carried on at the old Sanderson Works of Crucible at Syracuse, New York. Mathews goes on to say that Gledhill of England and Taylor himself had discussed the use of vanadium in 1904.

With the addition of about 1% vanadium to the 18% tungsten, 4% chromium and 0.60 to 0.80% carbon steel, the first truly universal high-speed steel was born. Not much was known at this time about the science or metallurgy of this class of steel, but then steel in general was little understood in those very early years of the 20th century. The fact that no one had any knowledge as to why this type of steel exhibited such unusual behavior in service did not prevent the researchers from maximizing the service performance to such an extent that even today this 18-4-1 high-speed steel (known commercially in the United States as T-1) is still in very limited commercial service. Although it has lost most of its popularity in the market place, this loss is due as much to economics as to technological obsolescence.

By 1905 the 18-4-1 high-speed steel was in commercial production and would remain the major tool steel for metal machining for the next 35 to 40 years. This predominantly American development with the Taylor and White heat treatment and the vanadium patent of Mathews would eventually be superseded by substituting molybdenum for most or nearly all the tungsten. But we're getting ahead of our story on the scientific studies and developments on high-speed steels.

A great deal of practical development work was done in the first 10 to 15 years after the initial discoveries. Cutting tests were laboriously performed by tool steel producers and users alike to optimize the many variables of alloy content, hardening temperatures, methods of cooling from hardening, and post-hardening heat treatments (tempering). Not all this work was performed with equal competence or similar results. Thus, the times spawned many ideas regarding what constituted the ideal tool material. This situation was further compounded by lack of understanding of the metallurgy involved in such high-alloy steels.

H. C. H. Carpenter of the British National Physical Laboratory reported on one of the earliest research investigations of the metallurgy of high-speed steels in 1905 and 1906. He studied the microstructural changes which occurred in many different English and American commercial steels as well as controlled laboratory alloys in which he varied the chromium, tungsten, and molybdenum contents. An interesting item in Carpenter's study was his recognition of J. A. Mathews of Crucible Steel as the supplier of the American alloys used in his study.

Carpenter, however, correctly concluded that Mo and W were the elements which provided the resistance to softening ( He cites LeChateleir, the famous French scientist, as previously arriving at this same conclusion.). He misunderstood the important role of Cr in providing the air hardening. He also believed that the high temperature phase (austenite) was the source of red hardness. He was led into this error because of the large amount of austenite he saw in samples after cooling from the hardening temperatures. However, Carpenter did realize that resistance to tempering was a separate subject worthy of study. The next year (1906) he performed tempering studies but did not shed any new light on the red hardness phenomenon with the limited tools of this time.

Another metallurgical research study was undertaken by a countryman of Carpenter's several years later (1908). C. A. Edwards, a Fellow at Victoria University at Manchester, studied the effect of Cr and W and considered hardness itself as a contributor to red hardness (Taylor had always thought of red hardness as a separate special property which could be studied only by cutting test). While Edward's first work did little to improve the understanding of the metallurgy of high-speed steel, he later collaborated with Kikawa (1915) to produce a landmark paper on the subject

. They performed hardness tests in a systematic study of the effect of Cr and W on tempering. This method showed the hardness peak after tempering at 1000 to 1200F. In fact using a steel similar to Taylor's recommendation they showed a secondary hardening peak at just the temperature that Taylor had predicted in his work 15 years earlier. Edwards and Kikkawa provided the first comprehensive understanding of the major metallurgical phenomena in high-speed steel. They concluded that Cr imparts the self-hardening, and the extremely high temperature for hardening was needed to dissolve the tungsten. The maximum resistance to tempering (or maximum secondary hardening peak) can only be obtained by getting the tungsten into solution. They also concluded that careful tempering studies with hardness measurements could provide valuable information on the relative merits of cutting tools (expensive and time consuming cutting tests had been the only reliable criterion up to this time). Interestingly, the tempering of higspeed tools at 1050-11500F was not recognized as of prime importance until after WWI.

Edward's and Kikkawa's research was certainly recognized by the eminent European metals researchers of their time. This paper was followed by 15 pages of technical discussion submitted by such renowned workers as Carpenter, Hadfield, Rosenhain and Stead. No Americans entered into the discussion, and it is not clear that this milestone paper ever received the recognition it deserved in the United States, either at the time it was published or later.

Shortly after Edgar Bain's early work using x-rays to determine the crystal structure of austenite (FCC) and martensite (BCC), he and Zay Jeffries published their famous paper in Iron Age in 1923 on the "Cause of Red Hardness of High Speed Steel". This paper is a classic in the field of metals technology, not so much because it changed industrial practices , but because it combined the latest research tool (x-ray diffraction) with the latest theory of hardening(slip interference by precipitated particles). Bain performed the x-ray work, and Jeffries supplied the slip interference concept.

This paper showed, as concluded earlier by Edwards and Kikkawa, that the high-hardening temperatures are needed to dissolve the particles of tungsten-containing carbide in the austenite. Bain and Jeffries then concluded that the softening of hardened steel during tempering, which occurs in ordinary steel at low temperatures (300 to 900F), is caused by grain growth and carbide particle growth beyond the critical size. They reasoned that the greater stability of the tungsten carbide forces its formation at the higher temperature. It is only at these temperatures that the larger tungsten atoms can move within the metal space lattice to form the alloy carbides. It would be many years before most of the concepts proposed by Bain and Jeffries could be properly evaluated. Later studies would show they were correct in the thrust of their theories, but the details of alloy carbide formation would be more complex in detail.

The following year, 1924, Edgar Bain moved from General Electric Company to Atlas Steel Company in Dunkirk, New York. Here he worked with one of America's most interesting and prolific metallurgist, Marcus A. Grossman. The publications of Bain and Grossman in 1924 included high-carbon, chromium steels, chromium in high-speed steel, and their major work "On the Nature of High Speed Steel", which they published in Great Britain (Journal of The Iron and Steel Institute) rather than in the United States. This paper was a compilation of the arts on the manufacturing and the metallurgy of high-speed steel. In some ways it appears ;to be a combination of Grossman's practical knowledge with the metallurgy and the theory reported earlier by Bain and Jeffries. Grossman and Bain expanded this effort in their collaboration in 1931 with the publication of a textbook entitled "High Speed Steel".

A shortage of tungsten during WW l forced many users of high-speed steels to fall back to using carbon steels, a regression of 50 years in technology. After the war, a major research effort in high-speed steels was to substitute molybdenum (the sister metal for tungsten) in the T-1 alloy of Matthews. Work was done at Watertown Arsenal in Watertown, Massachussets under General T.C. Deckerson and Captain Ritchie, and later under Dr. Michael G. Yatsevitch and G. K. Jenks during the late 1920's and early 1930's. The approach in this work was to substitute about 9.5% Mo for the 18% tungsten in T-1. This is about a one-for-one atomic substitution. Since Mo has only one-half the atomic weight of W only about one-half weight percent is needed. Major accomplishments were the use of a borax coating during heat treating to protect the surface and better yet the use of molten salt baths for heating these steels during hardening. Previous drawbacks on all prior high-molybdenum tool steels had been the excessive loss of carbon at the surface during heating.

It was only natural that an army arsenal would be vitally interested in developing Mo high-speed steels. The United States was dependent upon other countries, especially in Asia, for the bulk of its tungsten. Shortages during the war showed the strategic need for finding a substitute. The United States did not have much tungsten, but there were known to be large deposits of molybdenum in the mountains of Colorado.

A small mining and refining venture was started by several of the principals of the American Metals Company in1918 to produce molybdenum for alloy additions in armaments such as tanks and guns for WW I. This very small activity took the name of a local railroad station nearby, Climax, Colorado. The mine was shut down completely after the war because of the small demand for the product. Within a few years, however, consumption increased at a rapid pace aided by the increasing use of alloy steels in general, but especially in the rapidly growing auto industry. A quaint advertisement, one among many to appear in The Saturday Evening Post, Literary Digest and Scientific American during the mid 1920's, shows the Wills auto to be superior because of its use of molybdenum alloy steel. Fortunately, the use of Mo in steel turned out to be more viable than the Wills automobile.

With increased supplies from the Climax Molybdenum Company of Michigan, the price of the metal was finally reduced until it became competitive with tungsten for high-speed steel. Price alone, however, was not the deterrent to replacing tungsten with molybdenum. Technical acceptance in the industrial marketplace among the tens of thousands of tool makers, tool room foreman, and machinists was the final demand that had to be satisfied. The Watertown Arsenal work was interesting, and many applications were found for the molybdenum (tungsten-free) high-speed steel within the various arsenals around the country, but it never gained acceptance in industry as a competitor of T-1.

The first significant breakthrough in the commercial development of Mo high-speed steels was work performed by Joseph V. Emmons at the Cleveland Twist Drill Company (CTD) in Cleveland, Ohio. Emmon's work was undertaken in the late 1920's and continued through the dark economic times of the 1930's. In 1933 Joe Emmonds received his patent and published a technical paper. Both were models of clarity and precision. Briefly he reported that all-molybdenum (ie, tungsten-free) steels were in fact inferior to T-1. He also pointed out that substituting small amounts of molygdenum for some of the tungsten was not worthwhile. His major discovery was that a ratio of about 4 parts Mo to 1 part W for a total of 10% of the steel provided a critical composition that could compete against the 18% tungsten of T-1. His paper entitled "Some Molybdenum High Speed Steels" was presented in Buffalo before the national conference of ASM in October, 1932. It won the coveted Henry Marion Howe Medal for that year.

Later an interference was declared by the Patent Office between Emmon's application and one by Frank Garrat of Universal Steel Company. This interference was resolved by Garrat conceeding priority to Emmons and CTD licensing Universal to make the steel. Patent No. 1,937,334 was issued to Emmons on November 28, 1933.

By the end of the 1930's, other patents by Emmons, by Gill at Vanadium Alloy Company and others provided a sound basis for commercial development of the new steels when the tungsten shortage occurred again during WWII. In fact the Cleveland Twist Drill Company had already provided a significant body of experience in this commercial work by their use of these steels under the leadership of Emmons with the cooperation of the tool steel producers, especially Crucible and Universal. Industrial practices, however, die hard and at the time of our entry into WWII over 80% of the high-speed steels were still of the tungsten type. The War Production Board provided the encouragement for the massive transfer to molybdenum by denying the tool steel industry the tungsten to maintain production. Thus molybdenum high-speed steels became the dominant type during WWII and after.

Although many tool steel companies and their customers contributed to this major transfer to molybdenum high-speed, J. V. Emmons and the Cleveland Twist Drill Company were true pioneers in this most important shift in tool steels since the heat treatment of Taylor and White. Americans in general know little or nothing about such technological pioneers and the industrial companies who support their efforts. Even though Emmons was born several years before Jeffries, Grossman and Bain he outlived them all and most other of his contemporaries.

Joe Emmons was interviewed in his 90th year during the fall of 1978 to discuss his long career in metallurgy and his more than 50 years at the Cleveland Twist Drill Company. He was born in the little village of North Lewisburg, Ohio, where his father was a physician. After graduation from Lebanon Normal College, he enrolled at Case in Cleveland. He left Case after a short time because of a lack of funds and took a position in Cleveland as a blast furnace chemist. Within a few weeks he joined Cleveland Twist Drill Company as assistant chemist. This was in 1909.

Emmons was soon involved in metallurgical work which included heat treating and metallographic studies. His comments on how he took up working on the microscope are typical of his time: "After Mr. Chapin, the Chief Chemist, left the company, I was asked if I was interested in a correspondence course that the company had purchased for him." This course was published by Sauveur and Boylston of Harvard University. "As I had a lot of experience when a boy with a microscope in my father's office, I was happy to have this opportunity." Emmons was able to apply his new found knowledge immediately to practical tool steel problems. His work soon lead him into unknown areas, and he turned for advice to the Dean of American metallurgists: Henry Marion Howe. Emmons visited Howe at his home in Connecticutt to discuss his findings. These efforts led to his first important publication, which, with Howe's help, was published by the American Institute of Mining and Metallurgical Engineers in 1914.

Emmons's work at CTD brought him into contact with all the high-speed and general tool steel producers. Many of these companies were formed during the early years of his career, just before WW I. His interests and activities also provided the opportunity to know and work with other leading metallurgists of his time. He counted as good friends Bain, Grossman, Howe, Jeffries, and many others who were working on tool steels and alloy steels in general. Emmons related an interesting story about his relationship over the years with Zay Jeffries. In his first years at CTD he did some outside consulting work with a Mr. Benbow at the National Lamp Division of the General Electric Company. Mr. Benbow wanted more time than Emmons could spare, so he recommended a young instructor he knew at Case: Zay Jeffries. Emmons and Jeffries developed additional mutual interests when Jeffries undertook studies in high-speed tool steels. However, Emmons said that Jeffries was opposed to his ideas on substituting molybdenum for tungsten in high-speed steel. By this time Jeffries had built a considerable reputation on the metal tungsten for lamp filaments and tungsten carbide tools. Thus he did not take kindly to ideas which would displace his favorite metal, tungsten. Emmons commented that later Jeffries was not such a good friend. Professional jealousies exist in all fields.

Emmons continued his research during the difficult economic times of the great depression. He enjoyed describing his discussions with the top manager of CTD on budgeting $10,000 a year to continue the work. Obviously it takes a competent technical worker and an understanding employer to perform and fund long-range development during such times as these people faced in the 1930's. Toward the end of the depression as the threat of war turned into grim reality in Europe, the improvement in machine tool business permitted CTD to make an important decision. They provided a significant boost to the manufacture of molybdenum, high-speed steel by ordering over a $1,000,000 of these commercially untried steels based on their confidence in Emmons and his 15 years search for the best replacement for T-1. Emmons commented " Col. Dillard (General Superintendent of CTD) and I discussed the problem and he said: "If we change over to this new molybdenum steel and for some reason we cannot now foresee, our customers will refuse to accept tools made from it, we will probably wreck the company. The least that could happen would be that we would both lose our jobs. On the other hand, if being in possession of these proven facts of its good performance, we do not have nerve enough to make the change, we ought to lose our jobs". I told him that I had confidence in the steel and would lay my job on the table. He said " so will I". Orders were placed and from this time on no more 18-4-1 high-speed steel was purchased by the company". Modern high-speed steel compositions which fall under various patents issued to Emmons are M-1, M-7, M-30, M-33, M-34, M-42, M-43, M-46, and M-47.

A major contribution to the metallurgy of high-speed steels during the 1930's was made by three Germans: E. Houdremont, H. Bennek, and H. Schrader. After examining the tempering behavior of 1.5% carbon steels compared with steels containing 1.5% carbon + 8% tungsten, they stated "...no essential difference is to be found between tungsten steel and carbon steel when quenched from normal temperatures. Tungsten steel when quenched from higher temperatures exhibits a greater stability of hardness upon tempering than carbon steel. This cannot be ascribed to an increased retention of austenite and consequent transformation of the residual austenite upon tempering because repeated tempering at increasing temperatures would progressively decompose the residual austenite into martensite, which in turn would soften, not harden; all samples in the present study were tempered eight times. It is reasonable to suppose that the precipitation of tungsten carbide occurs progressively on tempering at higher temperatures and that this is the cause of the improvement in the stability of hardness upon tempering".

The German authors then turned to a more detailed study of vanadium in steel of various carbon contents from 0.01 to 1.0%. Borrowing from work performed as early as 1911 by F. Rittershauser and adding considerable laboratory work of their own, they concluded that vanadium carbide dissolved into austenite at temperatures well above those used in hardening steel. Upon quenching and tempering a kind of precipitation-hardening occurred which could be caused only by the formation of the special vanadium carbide at the higher tempering temperature, similar to those found in high-speed steels.

This German paper was published in the United States by the American Institute of Mining and Metallurgical Engineers in 1935. Amazingly it attracted little attention at the time and was referenced only in a passing fashion for 15 years or more, until it became more generally recognized that secondary hardening was truly a precipitation hardening phenomenon. This German work at Krupp ranks with the research reported 20 years earlier by Edwards and Kikkawa of Britain as two of the finest contributions from Europe on high-speed steel. In both instances American researchers seemed little influenced at the time. This attitude is harder to understand in the case of the German work, since it was published in an American journal. In defense of provincial attitudes, however,it should be noted that the Houdrement, Bennek, and Schrader paper contained not one reference to any prior American or English work, not even the milestone paper by Jeffries and Bain.

It was now 40 years since the discovery of the high-speed steel heat treatment by Taylor and White and 15 years since Bain and Jeffries published their theory of secondary hardening. While practical development of the Mo high-speed steels was accomplished during this time, little was done to develop a more fundamental understanding of the materials. A young professor of metallurgy at the Massachusetts Institute of Technology, Dr. Morris Cohen, set about to develop an understanding of the nature of the tempering of high-speed steel. Starting in 1939 studies were published by Cohen and a series of graduate students who did their doctoral theses on high-speed steel. These young Ph.D.'s were P. K. Koh, Paul Gordon, Bernard Lement, Otto Zmeskal, Stewart Fletcher, Dana P. Antia, George Roberts and Donald Blickwede. This was an outstanding group of young metallurgists, not only for the work they did under Professor Cohen, but for the other contributions they have made during their careers. Several of them became professors of metallurgy, including department heads in their universities, one became Director of Research at a top steel corporation, another was Executive Director of the American Iron and Steel Institute and one became president of a large American corporation.

The first paper by Cohen and Koh (1939) set the tone for most of the papers that followed. They reviewed the literature on secondary hardening, which showed that most previous researchers believed the high-speed phenomenon was caused by the transformation of residual austenite to martensite during tempering. Considerable, so-called, residual austenite was always seen in the microstructure of as-cooled high-speed steel, but it was replaced by martensite after tempering. Cohen and Koh studied changes in properties after heat treating at various temperatures and times. The variable of time at tempering temperature had never been examined adequately. In addition to x-ray diffraction on solid samples, they studied changes in electrical and magnetic properties, length, volume and hardness. They concluded that there were four stages to the reactions in high-speed steel during tempering:

1. The formation of iron carbide (Fe3C)

2. The precipitation of carbide in the retained austenite

3. The transformation of this retained austenite to martensite

4. The precipitation of alloy carbides in martensite

The Cohen and Koh paper showed for the first time in American technical literature that the retained austenite did not transform to martensite at the tempering temperature but on cooling from this tempering temperature. Time spent at the tempering temperature conditioned the residual austenite for this subsequent transformation. The basic conclusion was that stages 2 and 3 contributed secondary hardening. This conclusion continued the conventional wisdom that somehow the transformation of retained austenite was the cause of secondary hardening, or red hardness and that the eventual formation of alloy carbides upon long exposure to temperatures of 1100F or higher was not significant. This initial paper by Cohen and Koh was of much practical importance to the tool steel heat treaters and users as well as a document concerned with the theory of secondary hardening.

Over the next decade Cohen and his students continued their research studies on steel. Some work was directly applicable to high-speed steel, other was more basic to steels in general. The work on tempering high-speed steel showed that little was understood about the tempering of all hardenable steels. Such a study was undertaken by Antia, Fletcher and Cohen and reported in 1944. One of the last papers in the high-speed steel series (Cohen and Blickwede) was on the effects of vanadium and of carbon on a 6% tungsten-5% molybdenum high-speed steel. This new steel was becoming very popular in industry under the designation M-2. The study was performed on the full range of carbon and vanadium contents which would ever be useful in high-speed steel. This work was important to later research on M-2 to produce ultra-high hardness steels.

Walter Crafts and John Lamont of the Union Carbide and Carbon Research Laboratories published a paper in 1948 which was of importance to high-speed steel. Union Carbide was a major supplier of ferroalloys, especially ferrochrome, to the steel industry. They built one of the earliest Metallurgical Laboratories in this country (first on Long Island and later in Niagara Falls, New York) and made many contributions in stainless and alloy steels. Crafts and Lamont were studying the effects of alloys in ordinary engineering-type steels. They had increased the amount of alloy until they were approaching the alloy content of tool steels. They found secondary hardening peaks after tempering, even though their steels did not contain residual austenite from quenching. This work finally killed the retained-austenite theory, so stubbornly held since the days of Carpenter over 40 years previously.

What was even more important was their work on the newly developed electron microscope. Time and again breakthroughs in research equipment leads to quantum jumps in knowledge or developments. The basic study of physical metallurgy had started with the light microscope, as modified by early metallurgists, then the high-temperature measuring thermocouple of LeChatelier, x-ray diffraction analysis of the Braggs, and by the 1940's the electron microscoope, where a stream of electrons rather than light rays, was used to see objects many times smaller than previously could be detected. Although Craft's and Lamont's work was done at magnifications only about twice that available by light microscopes, they found tiny carbide particles forming at tempering temperatures corresponding to the high-speed steel hardening peak. These small carbides were found by x-ray diffraction to be the alloy carbides of Mo2C, W2C or VC in various Mo, W or V steels. Crafts and Lamont were pioneers in using the electron microscope to study carbide precipitation in alloy steels. This initial work supported the now 25 year old theory of Jeffries and Bain that alloy carbides were the direct cause of secondary hardening in high-speed steels.

The next major contribution to high-speed steels came from a most unlikely source. Up till now high-speed steels were primarily an American development. There had been important contributions by English, French, and German metallurgist, but the major acts were always dominated by American researchers and American companies. This fact is what makes the next episode in our high-speed steel story so unusual that it is called "The Chinese-Swedish-English Connection". Mr. Kehsia Kuo, a research chemist, who was born in Peking and educated at the University of Chekiang, China, traveled to Sweden in 1949 to study metallography under Professor Emeritus Axel Hultgren at the Royal Institute of Technology, Stockholm. Later he moved to the University of Upsala to study carbides under Professor Gunner Hagg. These two Swedish researchers had international reputations in their respective fields, and Kehsia Kuo was an exceptional student. The result was a series of research papers published over a period of four or five years in the British Journal of The Iron and Steel Institute.

Kuo's first major work was a study by the latest techniques the x-ray diffraction of the carbides that form in steels alloyed only with chromium, molybdenum, or tungsten. As part of this work he examined the carbides that form in commercial high-speed steel. Included in the commercial steels were the old standby T-1 as well as M-2 and several European steels along with some of these same steels with cobalt additions. Kuo reported that the first alloy carbide to form when tempering high-speed steels in the temperature range where secondary hardening occurred was W2C for high -tungsten steels and Mo2C for molybdenum steels. At still higher temperatures where the hardness decreased rapidly the W6C and Mo6C carbides were found. Since tungsten and molybdenum are sister metals and formed the same type carbides, they could be combined and the carbide then considered M2C or M6C where M stands for the metal atom, be it either tungsten or molybdenum or a combination of them. Kuo concluded that the formation of this M2C carbide is the cause of secondary hardening (and red hardness) and that the transformation of retained austenite was not needed to explain the increased hardness. Later Kuo showed, by using the very latest techniques of the electron microscope, that the M2C carbide first precipitates as extremely fine thread-like particles which were visible at magnifications of about 100,000 times their actual size.

Thus over 50 years after the discovery of high-speed steels and their unique heat treatment, the true cause of their very high secondary hardness and their red hardness was most clearly presented by the Chinese-Swedish-English Connection. Kehsia Kuo returned to China in the mid-1950's to apply his considerable talents in helping his people who were now completely taken over by Mao and his Communists.

Developments on the American scene during the 1950s and the 1960s were largely in the replacement of T-1 and its relatives with M-1, M-2, M-7, M-10, and other molybdenum grades. Research work shortly after WWII by Walter Crafts and John Lamont at Union Carbide Corporation led to a concept of a balanced composition in the tempering of alloy steels. This concept was based on adjusting the carbon and alloy content to supply just the right balance for fulfilling the needs of the various carbides that formed during the critical stage in tempering. This concept was applied first to high-speed steel by Stevens, Nehrenberg, and Phillips at the Crucible Steel Company, and later by Hamaker, Handyside and Yates at Vasco Metals Corporation. These studies produced a series of steels which optimized the composition of previous high-speed steels by increasing the carbon content to fulfill the balanced designed concept and adding 5-8% cobalt to obtain the highest hardness ( RC 68) ever consistently obtained in high-speed steels. Cobalt had been used in high-speed steels since the earliest days, but sound laboratory evidence of its value was not available until this recent work.

Other work in this area which provided broader metallurgical data on these optimized-composition steels was presented by Stewart Fletcher and C. R. Wendell of Latrobe Steel Company in 1966, the year that Fletcher was President of the American Society for Metals. It was nearly 25 years previously that he had done his first work on high-speed steel at MIT under Professor Morris Cohen. These new high-speed steels (M-42,etc.) with their ability to machine harder materials, especially the jet engine superalloys and the space-age metals that were being developed at this time, have taken their place beside the regular molybdenum steels of Emmons and the older tungsten types, which are fast disappearing from use.

The story of high-speed steels is largely the history of small, specialty steel companies (Bethlehem Steel was the only large steel company to produce a line of tool steels.): Atlas Steel, Braeburn, Carpenter, Columbia, Crucible, Firth-Sterling, Latrobe, Simonds and Universal-Cyclops. It is the story of older steel plants concentrated in Pennsylvania and New York. Most of these companies made many special tool steels for dies, punches, saws, and hundreds of other applications needed in the emerging technological age. Many of these same companies branched out into other special alloys which are natural for their particular technical abilities. They produce stainless steels, jet engine alloys, metals for nuclear power, alloys for the electronic age, and other high-technology alloys. Still, many are known first and foremost for their contributions to high-speed steel.

Modern man existed for thousands of years as a simple toolmaker before he discovered metals. Gradually he learned to make to make useful, beautiful, even exquisite works from native gold, silver, and copper. Later he learned to melt, alloy, and cast-to-shape objects in bronze. Still later out of India came Wootz steel with the technically advanced art of hardening steel by heat treatment. This bit of advanced technology was worthy of 20th century science and engineering. Hardened steel was never plentiful in ancient times and required an art that waxed and waned over the centuries until crucible steel melting was rediscovered in England at the start of the Industrial Revolution.

It is now well over a century since the first alloy tool steel was invented by Robert Mushet, and a century since the discovery of the special heat treatment by Taylor and White. In this brief historical time our modern technological society came into being in no small way because of the availability of modern cutting tools with high-speed steel. These special metal researchers deserve recognition as contributors to this society. Names such as Mushet, Brustlein, Taylor and White, Edwards and Kikkawa, Mathews, Bain, Jeffries, Grossman, Emmons, Cohen and his many graduate students, Crafts and Lamont, Kuo, and a host of other workers who made important contributions to this field, even though they are not named specifically in this story, will always be known as the "TOOL MAKERS".

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