In 1954 Krivsky received his doctorate degree in metallurgy at the Massachusetts Institute of Technology and immediately accepted a job offer in the Metals Research Laboratory of the Union Carbide Company at Niagara Falls, New York.
Being knowledgeable in the chemistry of steelmaking, Krivsky became interested in two English papers that described the injection of oxygen into molten metal to produce extra low carbon stainless steel. In so doing, however, the temperature of the bath soared to well over 3,000 ºF, a temperature that severely damaged the furnace lining, putting an end to further experiments with oxygen injection. In a flash of genius Krivsky saw that a possible solution to that problem would be to dilute the oxygen with the readily-available inert gas, argon, while also being fully aware that Linde Air Products, a subsidiary of Union Carbide, produced both oxygen and argon.
Testing his theory, Krivsky made a hundred-pound heat of stainless steel in an induction furnace, lancing it with both oxygen and argon. The carbon content of the heat was well below 0.03% which was specified for Extra Low Carbon (ELC) stainless steel, a grade which was not susceptible to intergranular corrosion.
Further trials in the hundred pound furnace verified his first result and Krivsky, realizing the significance of his discovery, set about writing a patent application.
AOD Vessel
Attempts to speed up the process to a one-tonne furnace, however, were not successful. After almost a year of experiments Krivsky and his superiors decided that trials in a larger furnace might be more successful. Arrangements were made for tests at Haynes Stellite, a subsidiary in Kokomo, Indiana, in their three and five ton furnaces. Metallurgists at Haynes, however, had no success whatever in achieving low carbon contents. Union Carbide then approached the leading stainless steel producers in the hope of finding a partner in developing a large scale argon-oxygen-decarburization process. There was no interest whatsoever until Joslyn Stainless Steel, a small stainless steel producer in Ft. Wayne, Indiana, agreed to tackle the problem.
By this time Krivsky, who was no longer involved with the Argon oxygen decarburization (AOD) project, had accepted an attractive offer to become Vice President and General Manager of the Beryllium Company of America in Reading, Pennsylvania, a large step up for a man just turned thirty.
The Joslyn metallurgists worked diligently on the problem, testing one design after another of systems of injecting the oxygen and argon. It was impossible for them to achieve uniform distribution throughout the metal. They became utterly discouraged and decided to give up on many occasions, only to come up with other ideas. Five years had passed with Union Carbide’s continued support of the project. The Joslyn people finally decided that proper distribution of the gases in a melting furnace was not possible. What was needed was a separate refining vessel designed especially for that purpose. This approach had been resisted because of the added cost of another vessel in the refining process.
They proceeded, though, to test this hypothesis and built a three-quarter ton refining vessel to see what would happen. The vessel provided for top blowing with oxygen and bottom blowing with argon. The first results were extremely encouraging, confirming Krivsky’s experiments, but there was still a reluctance to build a large-scale refining vessel. They resumed testing in the 15 ton furnace but without success. Finally, in 1962, managers at Union Carbide and Joslyn agreed to go ahead with a large refining vessel. Dozens of vessels were built and hundreds of heats were produced without achieving uniform distribution of oxygen and argon. The records do not report any attempt to mix the two gases before injection.
On October 24th, 1967, after five years, the first successful heat was made by the AOD process. The carbon level was an unbelievably low 0.008%. It had taken thirteen years altogether. A full-scale vessel was built measuring nine feet in diameter with a height of thirteen and one-half feet. Tuyeres for argon and oxygen were installed on the lower back side of the vessel. During 1968 100 heats of stainless steel were refined with excellent results. The process clearly provided the low carbon content needed to eliminate the threat of intergranular corrosion.
The first refining vessel was modified and the entire stainless steel production at Joslyn was converted to the AOD process in July, 1969. In December Joslyn metallurgists astounded participants at the annual Electric Furnace Conference in Pittsburgh with a report on the result of 1300 heats produced by the AOD process. They said that Extra Low Carbon stainless steel could be produced with ease and with the following advantages:
1. The ELC steel prevented the formation of chromium carbides at grain boundaries eliminating the possibility of intergranular corrosion.
2. The production rate was doubled.
3. Lower refining temperatures reduced refractory costs.
4. Removing the refining and finishing operations from the arc furnace more than offset the operating costs of the AOD vessel.
5. The yield of metallic alloying elements was increased.
6. Lead was kept at very low levels of around 0.007%.
7. Sulfur, oxygen, hydrogen and nitrogen levels were far lower than previously possible.
8. The consistency, control and reproducibility improved ductility, fatigue strength and the machinability of many alloys.
9. It became possible to add nitrogen within very close limits for new nitrogen-hardening alloys.
10. The refinements of the process opened the possibility of developing new alloys.
Commercialization of the AOD process
Beginning early in 1970 Union Carbide and their subsidiary, Linde Air Products, began an ambitious plan to obtain AOD licensees around the world and to offer demonstrations at Joslyn. There were few takers at first. It was guessed that most firms resisted the payment of a fee for each ton of stainless steel produced and, at the same time, were hesitant about adding another step to their operations. Joslyn was the first, having gotten their license in 1968, followed by Haynes Stellite, although not a stainless steel producer, in January 1970. Viola of Italy signed on in July 1970 followed by Electralloy of Oil City, Pennsylvania in September and Eastern Stainless Steel of Baltimore in December. Only five licenses through to the end of 1970 was not an auspicious beginning.
(As an aside, it should be mentioned that Krivsky gave a paper on “The Linde AOD Process for Stainless Steel: A Case Study of Major Innovation in a Basic Industry” at a meeting of the Metallurgical Society of AIME in 1973. He was then president of Specialty Metals, a division of Colt Industries.)
By 1982, however, 79 AOD vessels had been installed in 60 steelworks and 24 foundries throughout the world and, by the year 2000, the total reached 100 installations. Krivsky lived to see that happen. Dr. William A. Krivsky died in 2006. It could well be said that he invented the Krivsky Argon-Oxygen-Decarburization Process. He was the Henry Bessemer of Stainless Steel. That’s who Bill Krivsky was.
