US3556777A - Ferrous alloy containing high manganese and chromium - Google Patents

Abstract

A FERROUS ALLOY WHICH IS PARTICULARLY SUITABLE FOR USE AS A WELD DEPOSIT FOR STRUCTURAL MEMBERS. THE ALLOY, WHOSE CONSTITUENTS ARE LISTED BY WEIGHT PERCENT ARE AS FOLLOWS:

PERCENT CHROMIUM 1.0-4.0 CARBON 0.60-1.60 SILICON 0.30-1.00 MANGANESE 22.0-36.0 NICKEL 0-5.0 MOLYBDENUM (MAX.) 1.50 PHOSPHORUS (MAX.) 0.015 SULFUR (MAX) 0.015 IRON, BALANCE

EXHIBITS EXCELLENT MECHANICAL PROPERTIES ALONG WITH SUPERIOR RESISTANCE TO ABRASION AND IMPACT.

Description

United States Patent O 'ice 3,556,777 FERROUS ALLOY CONTAINING HIGH MANGANESE AND CHROMIUM Howard J. Petry, West Alexandria, Ohio, assignor to Rexarc Incorporated, West Alexandria, Ohio, a corporation of Ohio No Drawing. Filed Apr. 4, 1968, Ser. No. 718,941

Int. Cl. C22c 39/14 US. Cl. 75126 6 Claims ABSTRACT OF THE DISCLOSURE A ferrous alloy which is particularly suitable for use as a weld deposit for structural members. The alloy,

whose constituents are listed by weight percent are as follows:

Iron, balance exhibits excellent mechanical properties along with superior resistance to abrasion and impact.

BACKGROUND OF THE INVENTION The mining and highway construction industries have been two of the most rapidly growing industries in the United States. With this growth, there was an ever increasing need and demand on the machinery performing the material moving tasks. The increased demands brought a greater awareness of the economics of the particular methods for performing the assigned tasks. Such work varied from moving mud and rock to the extraction of the more corrosive materials, coal and metallic ores.

In the design of the machinery to handle these heavy loads, consideration had to be given to the ability of the materials to resist the wear and tear of'the constant use, and the abrasive action of the materials to be moved. With this requirement, designers turned to such alloy steels as the A181 high strength low alloy steels and the Hadfield manganese steels.

As the industry grew and the machines became larger and more complex, fabrication and maintenance problems increased. Changes had to be made in the field, Components were replaced or repaired by conventional techniques such as welding. It was not uncommon to weld dissimilar steels such as manganese steel, alloy steels and the high carbon steels.

To accomplish the foregoing, the industry turned to stainless welding rods, manganese welding rods and other alloy materials. However, the rods were inadequate. Crack failures, lowered mechanical properties of resistance to mildly corrosive conditions, and generally metallurgically unsound structures resulted. To applicants knowledge, it was not until the development of the present invention that a suitable welding rod was found for the industry which possessed none of the foregoing shortcomings. Structures could now be properly welded without cracks, reduction in properties or loss of corrosion resistance. Further, the welded areas have both impact and abrasion resistance comparable to the structural plates.

3,556,777 Patented Jan. 19, 1971 BRIEF SUMMARY OF THE INVENTION In the preferred practice of this invention, alloying constituents on the order of 27-50% are added to a ferrous base to produce an alloy which can be worked, by forging, rolling or extruding, to form a rod or wire suitable for use in welding. Specifically, the principal alloying constituents are manganese, carbon, nickel, chromium and optionally molybdenum. The limit of said additions are as follows:

Percent Carbon .60-1.6O Silicon .30- Manganese 22.0-360 Nickel 0-5.0 Chromium 1.0-4.0 Molybdenum (max.) 1.50 Phosphorus (max.) .015 Sulfur (max.) .015

Iron, balance.

The preferred range of the alloying constituents are as follows:

Percent Manganese 22.0-28.0 Carbon 0.70-l.2 Silicon 0.30-1 .0 Nickel 3.0-5 .0 Chromium 1.5-3 .0 Molybdenum 0.5-1.5 Phosphorus (max.) .015 Sulfur (max.) .015

Iron, balance.

DETAILED DESCRIPTION OF THE INVENTION It should be apparent from the foregoing that the principal application of the ferrous alloy of this invention lies with its ability to form sound welds in joining structural alloy steel plates. However, it is not intended that this alloy be so limited as other uses will become apparent to those skilled in the art. Since the alloy of this invention can be forged and rolled into various shapes, the versatility of the alloy becomes more apparent. However, for convenience, the invention will be described with reference to the particular application of welding rods. By welding rods, I intend to include both coated rods for manual use and bare wire for submerged are use.

A fabricated structure can be analogized to that of a chain wherein a new link has been inserted or substituted. To return the chain to its former capabilities, the new link has to be at least as good as the balance of the chain links. This in essence was the problem facing the prior artproduction of welds comparable to the primary structure.

In an attempt to improve the weld structure of fabricated products, the prior art turned to stainless and alloy steels. The stainless steels, while high in chromium to offer excellent corrosion resistance, did not give to the structure the required resistance to abrasion and impact. Further, the strength levels were well below the strength of the primary structure.

Since abrasion resistance is one of the most desirable properties in this area, the prior art began directing its attention to the 13% manganese Hadfield steels. This was due to the acknowledged effect of manganese on the hardenability of steels. Such steels were not without their shortcomings, however. Typically, in welding operation, the base metals and welding rods are melted and fused forming a distinct transition zone between the structures to be joined. Due to this melting and fusion, a rapid migration or diffusion of the manganese occurs, thereby depleting portions of said zone of manganese. And, an

alloy content of about 50-10% manganese is generally poor. This is believed to be the result of an unstable austenitic crystalline structure.

Since elemental migration or diffusion is a necessary incident to welding, it was proposed that higher manganese be employed to avoid the above recited critical range. However, a further restriction placed upon the prior art was the general belief that relatively low carbon values were necessary. For example, with 14% manganese electrode, carbon in excess of 70% tended to decrease the usefulness of the alloy. Further, in the welding alloy proposed in US. Pat. No. 3,266,876, issued to De Long et al., a maximum limit of 1% carbon was imposed on a 31% manganese steel.

It was discovered by the present invention that with the particular combination of elements, carbon up to 1.60% could be tolerated without cracking. It will be obvious to those skilled in the art that carbon is the least expensive of the recited alloy additions and is quite effective in contributing to the hardness and wear resistance of the alloy. Hence, the present alloy is not only effective but relatively inexpensive. It yields consistently high mechanical properties which are so essential to welding high strength structural plates.

The remaining alloy additions also contribute to the realization of the superior properties found in the alloy of this invention. Molybdenum, for example, which may be used With or to the exclusion of nickel, adds to the tensile strength of the weld deposits and further contributes to producing a desirable fine grained structure. The chromium is essential not only to provide an assembled structure which is resistant to mildly corrosive conditions, but it aids in tying up a portion of the carbon as carbides.

A typical welding alloy having a composition within the alloying ranges set forth above is as follows:

Carbon .86 Silicon .35 Manganese 22.05 Nickel 3.18 Chromium 1.63 Phosphorus 0.12 Sulfur 0.12 Iron, balance,

was found to possess these properties:

Tensile strength (k.p.s.i.) 144.2 Yield strength (k.p.s.i.) 96.5 Elongation (percent) in 1.4" 33.6

Impact (ft.-lbs.)

the as deposited hardness Was R -50. This was hardened to R 45-50.

It should be apparent from the foregoing that modifications may be made in the invention without departing from the spirit and scope thereof. Therefore, no limitation is intended to be imposed herein, except as set forth in the appended claims.

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. A Weld deposit for ferrous metallic structural members comprising a ferrous alloy consisting essentially by weight of about .60'-l.60% carbon, about .30'l.0% silicon, about 22.0-36.0% manganese, up to about 5% nickel, about 1.0-4.0% chromium, up to about 1.50 molybdenum, and the balance substantially iron, said deposit characterized by the properties of being resistant to cracking, and possessing high mechanical strength and resistance to abrasion.

2. The alloy claimed in claim 1 wherein the carbon is present in an amount of about 0 .701.2%.

3. The alloy claimed in claim 2 wherein manganese is present in amount of about 22.0-28.0%, nickel in amount of about 1.5-3.0%.

4. A ferrous alloy consisting essentially by weight of about .60-1.60% carbon, about 30-10% silicon, about 22.0-36.0% manganese, up to about 5% nickel, about 10-40% chromium, up to about 1.50% molybdenum, and the balance substantially iron, whereby said alloy exhibits excellent mechanical properties along with superior resistance to abrasion and impact.

5. The ferrous alloy claimed in claim 4- wherein the carbon is present in an amount of about -12%.

6. The ferrous alloy claimed in claim 5 wherein manganese is present in an amount of about 22.0-28.071, nickel in an amount of about 30-50%, and chromium in an amount of about 1.5-3.0%.

References Cited UNITED STATES PATENTS 1,333,151 3/1920 Becket -126B 1,561,306 11/1925 Brace 75--128A 2,038,178 4/1936 Jerabek 75-1231 2,156,299 5/1939 Leitner 75-126B 2,184,305 12/1939 Kropf 75-126B 2,357,885 9/1944 Franks 75-1263 HYLAND BIZOT, Primary Examiner US. Cl. X.R. 75128