US2402424A - Hard alloys - Google Patents

Description

Patented June 18,1946

' man ALLOYS Roy B. McCauley, Chicago Heights, Ill.

No Drawing. Application January 20, 1945,

, Serial No. 573,805

' 4 Claims. (01. 75-125) This invention relates to hard ferrous phosphide alloys characterized by high abrasion resistance as well as corrosion resistance.

This application is a continuation-in-part of my application Serial No. 476,965, filed February 24; 1943.

7 It is the object of the present invention to pro-- vide hard corrosion and abrasion-resistant phosphide alloys having a comparatively low phosphorus content with a disembrittling metal con-- tent consisting of chromium together with small proportions of grain refining metals consisting of copper and nickel in substantially identical quantities. The small quantities of the latter metals which are embodied in the alloys of the present invention permit a maximum output of these alloys for industrial uses despite the restrictive allotment of these metals at the present time.

I have found that the alloys in accordance with the present invention display an extremely permanent hardness without heat treatment. In

' fact, while the hardness may be critically controlled by the ingredients of the composition, the same remains unaffected by any heat treatments.

It is the object of the presentinvention to obtain tough, and hard ferrous alloys having a high degree of resistance to physical deteriorating influences as well as corrosion resistance which is particularly marked against oxidizing acids and brines oi the character of nitric acid and nitrates.

The properties of the alloys in accordance with the present invention render it particularly useful in the production of cast parts of pumps employed for handling, abrasive materials in subdivided iorm; production of the alloy in the form oi welding rod, strip, powder or other physical form to .be fused into union with surfaces to protect them against abrasive influences, for example, in cases of valves, valve seats, pump-rods, knives, pulverizing hammers, etc.; also centrifugally cast liners or surfaces for tubes or pipes.

These alloys are very active and alloy with other metals or alloys in the molten state, so that soft inserts needed in castings may be anchored by alloying with the cast alloys in accordance with the present'invention and special insert shapes for anchors will be thereby'rendered unnecessary.

The invention resides in a complex alloy of iron and phosphorus containing varying amounts .of

chromium and grain refining elements such as.

copper and nickel and in which any other elements such as-carbon, all in combined form, silicon, sulphur, manganese and aluminum may be present as impurities in quantities less than 1.00%

'since the elimination of suchfrom the alloy would prove too costly after these elements are introduced into the alloy as a result of their presence in the-scrap metal from whichthe alloy may be compounded. The advantageous results of the present invention are attainable 'by an alloy having the following essential ingredients therein. within the ranges indicated in addition to iron. v

Percent Chromium; From 10.00 to30.00 Phosphorus 'From 0.75 to less than 5.00 Coppers .From 0.50 to less than 5.00 Nickel; From 0.50 to less than 5.00

The iron and phosphorus are combined under circumstances that leave unoxidized phosphorus to react upon the iron with the result thatiron phosphide is formed, expressed by the symbol FesP. When the phosphorus is in a ratio as much as 1.70% to the iron, the mass 01' iron will be saturated with iron phosphide (FeaP). Increase of phosphorus up to 10.2% brings a eutectic alloy into existence consisting of the saturated solid solution FeaP distributed through the solid solution. Further-increase'of proportion of phosphorusup to 15.58% results in a body composed of the iron-phosphide plates surrounded by the eutectic alloy. Increase of the phosphorus materially above 15.58% fills the grain boundaries with iron phosphide and causes the whole alloy to exist as a compound.

As is generally known, combining phosphorus with iron under circumstances to produce iron phosphide produces a body which, while, highly resistant to chemical deterioration, is too brittle the grain of the chromium iron phosphorus alloy.

The use with copper of a grain refiner such as nickel has the function of promoting the solution of copper in iron.

My Patent No. 2,261,174, issued November 4, 1941, described the production of chemically resistant and physically strong quaternary alloys by combining 1.70%. to 25.0% phosphorus with 29.0% to 75.0% of iron in a manner to produce iron phosphide; adding to the alloy in a manner to also convert it into its phosphide, from 1% to 19% of a disembrittling metal which is one of the metals nickel, cobalt, copper, molybdenum and tungsten; and finally adding, in a manner to convert it into its phosphide, from 1% to 19% of a grain refining corrective metal which is not one of the disembrittling metals used but is one of the metals tin, mangenese, molybdenum, tungsten and vanadium, variance of phosphorus being provided for directly to correspond with the severity of corrosive environment in which the alloy is to be used.

One feature wherein the present invention differs from the quoted invention heretofore patented to me is that I have now discovered that by the use of relatively low proportions of disembrittling metal herein set forth, and particularly if the proportions of these two metals be kept closely alike, I get wholly unexpected results, in that whereas my patented formulae are the result of research aiming to produce quaternary alloys having high corrosion resistance, my present invention producesalloys all of which contain chromium and are hard or abrasive resistant; a collateral attribute of the present invention is that variation of proportions of which I call the disembrittllng grain refining elements can be regulated to a point to define a complete range of Rockwell hardness, to-wit: Rockwell hardness varying all the way from hard formulas that cannot be machined at all and finished only by grinding, to those that are soft enough to be machined, yet these abrasion resistant metals will all be corrosion resistant as well. The conditions are remarkable in that they are arrived at largely by radically small variations in the percentages of thedisembrittling and grain refining elements of copper and nickel, and by maintaining the proportions of these two metals closely the same.

The following series of formulae which may be grouped as coming within the herein recited general formula of the present invention illustrate the radical change in R/C hardness obtainable from a comparatively small change in corrective metal range:

a An alioyenibodying the present invention in the range of R/C test of 50 to 59 is:

Cr' 18.00 C11 1.00 Ni 1.10 P 5.00 Fe Balance An alloy embodying the present invention inthe range of R/C test of 40 to 49 is:

Cr 18.50 C" 1.00 Ni 1.10 P 4.00

Balance 4 An alloy embodying the present invention in the range of R/C test of 30 to 39 is:

Cr 22.00 Cu .50 Ni .50 P 2.00 Fe Balance An alloy embodying the present invention in the solutions of nitric acid, nitrates or brine. It can be cast in parts requiring a great deal of machining as it has a Rockwell hardness of from 20 to 30, C scale.

The type C alloy, which is slightly harder, is of the following composition:

Cr About 21.50 to 22.00 Cu About .25 to .50 Ni About .25 to .50 P About 1.75 to 2.25 Fe-.. Balance The hardness of this alloy ranges from 30 to 40 Rockwell, C scale, and machining of parts made therefrom is usually accomplished by using a carbide tool.

The iron phosphide alloys disclosed above containing a substantial amount of chromium with low phosphorus, nickel and copper contents, each below an upper limit of 5% produce a group of hard, tough, corrosion resistant and abrasion resistant alloys which have proven to be a marked advancement in the field of ferrous phosphide alloys known heretofore.

I claim:

l. A hard tough corrosion and abrasion resistant ferrous phosphide alloy requiring no heat treatment to develop its desirable properties and having a low phosphorus, nickel and copper content, each beiow an upper limit of 5% and including chromium in an amount of 10.00% to 30.00%. phosphorus from 0.75% up to its upper limit and substantially identical quantities of each of copper and nickel from 0.50% to their upper limits, the remainder being iron with other ingredients such as carbon, silicon and other elements being present as impurities in quantities less than 1.00%

2. A hard tough corrosion and abrasion resistant ferrous phosphide alloy requiring no heat treatment to develop its desirable properties and having a low phosphorus, nickel and copper content, comprising chromium from about 25% to 26%, phosphorus from 1.75% to 2.75% and substantially identical quantities of each of copper and nickel from 0.50% to 0.75%, the: remainder treatment to develop its desirable properties and having a low phosphorus, nickel and copper content comprising chromium i'rom about 21.50% to 22.00%, Phosphorus from about 1.75% to 2.25%.

copper from about 0.25% to 0.50% and nickel 5 from about 0.25% to 0.50%. the remainder being iron with other ingredients such as carbon, silicon and other elements being present as impurities in quantities less than 1.00%.

. 4. A hard tough corrosion and abrasion resistl0 ingredients such as combined carbon, silicon and.

other elements being present as impurities quantities less than 1.00%. l

' ROY B. MOCAULEY.