US2294834A - Hard surfacing alloy for ferrous foundation metal - Google Patents

Description

. the alloy for use for Patented Sept. 1, 1942 HARD SURFACING ALLOY FOR FERROUS FOUNDATION METAL Hugh S. Cooper, Cleveland,

half to Frank H. Wilson,

Ohio, assignor of one- Cleveland, Ohio No Drawing. Application June 5, 1941, Serial No. 396,698

4 Claims. (Cl. 75-126) This invention relates to metallurgy and more particularly to iron metallurgy and aims to provide an improved surfacing alloy adapted to be applied to ferrous foundation metal by welding processes. One of the objects is to provide a surfacing alloy having a fixed or determined hardness substantially unalterable by the heating and cooling incident to the weld application of the alloy to thegsurface of iron and steel foundation metal. Another object is to provide a weld rod comprised essentially of iron, chromium, columbium and carbon and containing small amounts of at least one of the associated metals Mn and Si, characterized by toughness, wear-resistant and corrosion-resistant properties and by a hardness before and after melting within the range of about 60 to 70 (Rockwell C.) Other objects and advantages will be apparent as the invention is hereinafter disclosed.

In accordance with these objects I have discovered that iron, chromium, columbium and carbon alloys containing from 20-'70% Cr, l-3% C, from .5 to Cb, balance Fe, except for small amounts up to about 1% of'at least one of the metals Mn and Si are characterized by a hardness value within the ranges 60 to '70 (Rockwell C) that is substantially unaltered by heating to fusion and cooling, and that by appropriate variations in the Cr content within the ranges given the toughness, oxidation and abrasion resisting properties ,of the alloy can be varied over a relatively wide range adapting a plurality of different purposes, such as for making edge cutting tools, filling in forging and drawing dies, for crusher jaws and stamp shoes, cement rings, pulverizer hammers, valve seats, farming implements, etc.

I have discovered that in high carbon Fe.Cr alloys containing Cr 20 to 70% and C 1 to 3%, additions of Cb within the range .5 to 5% markedly increase the toughness of the alloy and also refine the grain structure, the improvement increasing with increase in Cb within the range given.

The advantage gained by reason of the refined grain structure and improving toughness is a substantial increase in the resistance of the alloy to abrasion and shock.

I have further found that the remelting characteristics of such alloys, such as the fluidity and oxidation resistance of the alloys are beneficiated by additions of from small fractional percentages up to about 3% of at least one of .the metals Mn and Si.

properties of such alloys increase with increase in Cr content within the range 20 to 70% Cr, the alloys containing 40 to 70% Cr, for example, being exceedingly tough and hard with remarkable' resistanceto abrasion and corrosion and such alloys with-a carbon content of about 1% and a Cb contentfof about 2% may be hot forged into rods suitablefforuse as welding rods. The alloy containing" 3,0,;t0 35% Cr, carbon and columbium each about 3%, silicon and manganese eachabout 1%, balance Fe, is preferred, however, for general use where extreme toughness and hardness is desired. The hardness of this alloy approximates '70 (Rockwell C).

Alloys containing less than 30%. Cr and over 20% Cr are generally not as wear resistant as the 30-35% Cr but vhave excellent corrosion resistance and a higher resistance to shock.

The alloys of my invention are readily produced by melting down the constituents, preferably as ferro alloys, in an electric arc furnace;

Following fusion, the molten metal is held in the molten condition for a time interval sufficient to put all the carbon and carbides into solution, following which the molten metal is preferably chill cast to the desired shaped rods or bars adapted for use as weld rod material. The chill cast metal has a fine silky fracture.

The chill cast rods or bars may be readily re melted in an electric are by any of the welding processes now employed to form a fluid, free flowing molten metal readily uniting with all ferrous foundation metal, with the added advantage that the weld deposited metal is of substantially the same hardness on cooling as be: fore melting and requires no heat treating either to produce the desired hardness therein, tofore required, or to to the foundation metal.

Having hereinabove disclosed the present inventionbroadly and specifically and given several specific embodiments thereof it is believed apparent that the same may be widely varied without essential departure therefrom and all such modifications and departures are contemplated as may fall within the scope of the following claims:

What I claim is:

1. A hard surfacing welding alloy for iron and steel foundation metal, said alloy consisting of chromium 20-'70%, columbium .50-5.0%, carbon 1 to 3%, from small fractional percentages up to 3% of each of the metals manganese and sili- In general, the toughness and wear-resistant con, balance iron, said alloy being characterized by having a hardness within the range to as hereconsolidate the weld metal 1 unaltered by fusion 10 in: of chromium 40-70%, columbium 2%, carbon 1%, silicon and manganese each 1%, balance iron, said alloy being characterized by having a hardness approximating 65 Rockwell C before and after fusion and re-solidiflcation.

4. A hard surfacing welding alloy for iron and steel foundation metal, said alloy consisting of chromium 30-35%, columbium 3%, carbon 3%, silicon 1%, manganese 1%, balance iron, said alloy being characterized by a hardness approximating 70 Rockwell C that is substantially unaltered by fusion and resolidiflcation,

HUGH S. COOPER.