US2018752A - Alloy - Google Patents

Description

Patented Oct. 29, 1935 UNITED STATES PATENT OFFICE aoraisz ALLOY 1 Richard R. Walter, Starnberg, Germany No Drawing. Application May 7, 1929, Serial No.

361,263. In Germany December 3, 1928 7 Claims.

The tungsten carbides are extensively" used 10 in powdered form by the addition of metals of' lower melting temperature. It is known that the metal or metals to be added'for reducing the temperature of the sintering process should not exceed ten or at the most twenty per cent else 10 the alloy will lose its character and its requisite hardness.

The tungsten carbide alloys uniformly manifest a certain brittleness which in. manycases greatly delimits their field of usefulness, 'consequently, further to increase the additions of other metals, which are adapted to lessen brittleness, seemed corrective, but did not prove so because of the falling ofi in hardness which hitherto occurred. Accordingly, one object of my invention has been to produce a cutting and'wear-resisting alloy which will more successively combine the hardness property of the carbide with the added strength lent by another metal or metals. A further object has been successfully to increase the proportion of metal or metals to be, alloyed with the carbide or with a carbonitride of a metal of the chromium group. The new and useful r function of carbonitrides in this particular art is set forth and claimed in my copending application filed March 6, 1928, Serial No. 259,605.

Contrary to previous knowledge, I have discovered that tungsten carbide WC with six and twelve-hundredth per cent (6.12%) C permits of 40 substantially greater additions of metals adapted to improve the toughness and resistance to wear without unpermissible loss of hardness and that the presence of free or elemental tungsten amongst the auxiliary metals operates to especial advantage. While the sintered tungsten carbides of at least eighty per cent (80%) of carbide content hitherto permitted an employment of alloyed metals of not more than twentyp r cent 50 (20%); according to the present invention, the

55 enough.

particularly v ing atmosphere.-

It was discovered that the amount of free tungsten in my alloy (agreeable to its purpose) should not be much less than five per cent (5%,) and that more than thirty per cent (30%) of tungsten does not .produce an improvement in quality. 5

. I discoveredfurthermore, that the tungsten carbide can be successfully replaced with tungstencarbonitride (WxCxNx) or mixed with the latter. These complex combinations "manifest'a substantial increase in mechanical strength as compared with the carbides of greatest hardness and their resistance to wear exceeds that of the pure carbides.

The nitrification is facilitated and possible even with the metal tungsten if efiected subsequent tolli or simultaneous with a carburization, either while glowing in pulverized carbon or in the-presence of heat through transition of hydrocarbons and while exposed to dissociated nitrogen.

As auxiliary or alloyed metals, besides the tungsten content, one may use most of the metals of the iron and chromium groups (Fe, Mn, Ni, Co, and Cr, W. Mo, U respectively) either singly or several together. The carbides of the metals of these two groups are employed to advantage. As is known, a small addition of boron can en-- hence the degree of hardness where that is desired. e

The production of this alloy involves the usual method'of pressing together the pulverized ingredients followed by sintering in'anonoxidiz- The sintering temperature is generally below twenty-seven hundred and thrtytwo degrees Fahrenheit (2732 F.) and the comvmencement of the sintering is ordinarily under "twenty-five hundred and fifty-two degrees Fahrenheit (2552 F.).

For example, one alloy embodying thisinvention and which manifests especially good cutting 40 performances as a machining tool is composed of the following combination:

Sixty per cent (60%) W0 Twenty-six per cent (26%) W I Twelve and one-half per cent (12.5%) C0 One and one-half per cent (1.5%) CrzCa By utilizing aftungsten carbonitride one obtains a lathe tool alloy of exceptionally good cutting qualities, for example, with the following combination.

Fifty-nine per cent (59%) WC Thirteen per cent-(13%) 2WC%W3N2 Ei hteen pefeht (18%) w Ten per cent (10%) Co The nitrogen content ofthe carbonitride is suitably controlled so that, for instance, in a machining tool the amount of nitrogen in the complete alloy is less than one per cent (1%) whereas for other purposes, when great hardness is the primary desideratum, the nitrogen proportion may be greater.

All the alloys embraced by this invention likewise find advantageous application where it is desirable to ofl'er great resistance toimpairment or loss by service, for example, in pulling tools, dies, bearing blocks or pivots o'r sockets and moreover for earth and mineral drilling tools and allied duty.

It is to be realized that the scope of my invention comprehends other equivalent methods and combinations and that the particular description declares only a few specific exemplifications of an extensive series of successfully feasible combinations each modified according to the character of service for which trial has established them to be best adapted, respectively.

I claim:

1. A sintered alloy comprising mixtures of tungsten carbideand tlmgsten carbonitride together with addition of metals of the iron and chromium groups characterized in that tungsten carbide and tungsten carbonitride together as the chief component constitute at least fifty per cent and less than eighty per cent.

2. An alloy comprising less than eighty per cent of a carbide of a metal of the chromium group, about ten per cent of a metal of the iron group and of the same metal as that of which the carbide is formed a per, cent rangingfrom one-fourth to nearly one-half of the per cent 01 its carbide.

3. A sintered alloy comprising over fifty per cent of a carbide of a metal of the sixth periodic group, up to thirty per cent of a metal element of m the sixth periodic group and as remainder a metal of the iron group.

4. A sintered alloy consisting of chromium carbide between to tungsten between 15 to. 20%, and an iron group metal as remainder.

5. A sintered alloy consisting of 78 to 80% tungsten, 6 to 20% of an iron group metal, and 2 to 3% carbon, the tungsten being in the form of tungsten carbide and metallic tungsten.

6. A sintered alloy comprising a carbonaceous compound of a metal of the chromium group between 50 to 60%, the same metal in elemental form between 15 to 20% and as remainder, metal of the iron group. 7

7. A sintered alloy comprising tungsten carbide 25 over fifty per cent, elemental tungsten between somewhat less than5 to 30% and metal of the iron group as remainden RICHARD R. WALTER.