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Electro-Metallurgical Co. v. Krupp Nirosta Co.

June 30, 1941

ELECTRO-METALLURGICAL CO. ET AL.
v.
KRUPP NIROSTA CO., INC.



Appeal from the District Court of the United States for the District of Delaware; John P. Nields, Judge.

Author: Jones

Before BIGGS, CLARK, and JONES, Circuit Judges.

JONES, Circuit Judge.

This appeal involves a suit under Revised Statutes § 4915, 35 U.S.C.A. § 63, for a decree entitling the plaintiff, Electro-Metallurgical Company, to receive a patent for the invention specified in claims 1, 2 and 9 of a patent awarded to Paul Schafmeister, who assigned his rights therein to the defendant, Krupp Nirosta Company, Inc. Schafmeister was originally joined as a party defendant but the bill of complaint was dismissed as to him upon his filing a disclaimer in the court below.

The plaintiff, Electro-Metallurgical Company, is the owner of patent application Serial No. 593,928 filed by the other plaintiffs, Frederick M. Becket and Russell Franks, on February 18, 1932. Krupp Nirosta Company, Inc., is a Delaware corporation and is the owner of patent application Serial No. 550,288 filed by Schafmeister on July 11, 1931. In the oath accompanying Schafmeister's application reference is made to the fact that an application for a German patent of the same invention had been filed on July 21, 1930.

Interference between the above applications having been declared in the Patent Office, the Examiner of Interferences awarded priority of invention to Schafmeister and refused to grant a patent to Becket and Franks on their application. This decision by the Examiner of Interferences was affirmed by the Board of Appeals in the Patent Office on October 1, 1937. The Commissioner of Patents thereupon refused a patent to Becket and Franks. The plaintiffs did not appeal to the court of Customs and Patent Appeals from the decision adverse to them in the Patent Office, but instituted the present suit in the court below.

Each of the applications is concerned with a means or process for preventing internal (intergranular) corrosion in stainless steels. The invention in issue thus relates to an austenitic chromium nickel steel, - an alloy known as "18-8" steel, so named because it contains 18% of chromium and 8% of nickel. Stainless steel is practically immune to surface corrosion, but when subjected to a certain range of temperature (variously 400 degrees to 900 degrees C.) and to a corrosive, the chromium, which in itself protects iron against corrosion, combines with the carbon in the steel to form chromium-carbide. The resultant chromium-carbide. is deposited at the grain boundaries in the granular structure of the steel and deprives the individual grains of their protective chromium. Thereby it becomes possible for the corrosive to attack the iron. The ensuing damage to the internal structure of the steel, when subjected to the deleterious range of temperature, was a difficulty encountered in welding the steel or when the steel was used in chemical apparatus or in certain industrial operations such as oil cracking. If the carbon could be tied up by being brought into chemical combination with some suitable metal, it would no longer be free to unite with the chromium which, remaining in place as chromium, would continue to protect the grains of iron against corrosion.How to tie up the carbon in the alloy so that the chromium would be unaffected throughout the carbide-precipitation range of temperature was the problem to which the respective applicants addressed themselves.

The subject matter of the interference, as defined by the Examiner of Patents, was in ten counts, but the plaintiffs have limited their suit to counts 1, 2 and 9, which read as follows:

"1. A corrosion-resisting steel containing about 18% chromium, about 8% nickel, .07% to .2% carbon and from 0.3% to 2.5% of an additional material acting to lessen materially loss of corrosion resistance on prolonged holding at 500 degrees C., the balance substantially all iron, said additional material consisting substantially all of columbium.

"2. A corrosion-resisting steel containing about 12% to 30% chromium, about 7% to 25% nickel, about 0.07% to 0.2% carbon, and from 0.3% to 2.5% of an additional material acting to lessen materially loss of corrosion resistance on prolonged holding at 500 degrees C., the balance substantially all iron, said additional material consisting substantially all of columbium.

"9. A metal article which in its normal use is subjected to active corrosive influences while the metal in at least part of the article is in a condition resulting from heating at ranges within the carbide precipitation range (approximately 500 degrees to 800 degrees C.) without subsequent heting at substantially higher temperatures, said article being resistant to said corrosive influences and composed of a corrosion-resisting austenitic steel, the iron of which is substantially all in the gamma form, containing about 12% to 30% chromium, about 7% to 25% nickel, about 0.07% to 0.2% carbon, and from 0.3% to 2.5% of an additional material consisting substantially all of columbium and tantalum, the balance substantially all iron."

Prior to the discovery that an addition of columbium and tantalum to the steel alloy would improve its resistance to internal corrosion, the problem had been a difficult one in the art. Dr. Strauss of Germany, who had invented "18-8" steel about 1912, sought to eliminate internal corrosion by reducing the carbon content of the steel to .07% maximum, and in 1928 he disclosed that the reduction in carbon which he prescribed was helpful in preventing internal corrosion. However, the process of avoiding chromium carbide (when the steel was heated to a temperature within the deleterious range), by reducing to a minimum the carbon content of the steel, was both difficult and costly. It was then that Schafmeister and a colleague, Houdremont, who were working with Strauss at Krupp's in Germany, made a new approach by introducing titanium into the steel in order to engage the carbon in titanium carbide and thus keep the carbon from combining with the chromium. An application for a German patent of this process was filed by Krupp on June 26, 1929, and is in evidence in this case. The court below says that "By this procedure the trouble-maker was eliminated" and that the plaintiffs, Becket and Franks, "learned of this treatment in America and started their staffs of chemists to work." The appellants complain that there is no proof in the record to support these statements. We have examined the plaintiffs' Table F upon which the court below relied as showing that the plaintiffs were following the Schafmeister (Houdremont) titanium teaching and can see no more there than that the plaintiffs did make tests with zirconium, vanadium and titanium with, as the table shows, unsatisfactory results. In Schafmeister's American petition of 1931, based upon his German application of July 21, 1930, he specifies "considerable success" from the use of "elements such as titanium or vanadium" in the treatment of austenitic chromium nickel alloys.

In Schafmeister's 1930 German application, he set forth that extensive experiments had shown that the benefits to be derived from the use of titanium or vanadium (alone or in combination) in the alloy were also to be derived from niobium (columbium), tantalum, zirconium, uranium, hafnium, and other rare earth metals.He also set forth that it is advantageous in the use of these elements, as in the case of titanium, to establish such a relation of the stated alloy components with respect to the carbon that practically the entire amount of carbon is bound to the added alloy components. The application further stated that it was especially advantageous to use as the added alloy component one or both of the elements niobium (columbium) and tantalum, since these elements not only combine with the carbon in a manner which does not deleteriously affect the chemical and mechanical stability of the alloy but they furthermore result in particularly good welding conditions.

It was on the basis of this German application and Schafmeister's corresponding American application that the Commissioner of Patents (after decision by the Examiner of Interferences and the Board of Appeals) decided that Schafmeister was entitled to the date of his German application, namely, July 21, 1930. (Between July 10 and July 21, 1931, both inclusive, Schafmeister filed additional patent applications on ...


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