US2450888A - Wear resistant steel - Google Patents

Description

Patented Oct. 12, 1948 UNITED STATES ATENT OFFICE 2,450,888 WEAR RESISTANT STEEL No Drawing. Application July 2'7, 1946, Serial No. 686,725

4 Claims. 1

This invention relates to alloy steels, more particularly alloy steels containing not less than about 70 per cent b weight of iron and having a certain range of carbon content and being hardenable by quenching from above the critical temperature to a Rockwell C hardness of not less than about 53.

Those skilled in the art know that there are a considerable number of classes or types of alloy steels of the stated character such as hot work steels, air hardening steels, shock resisting steels, hardenable stainless steels, and many others. Within each class, there are numerous specifically difierent compositions so that the total number of specifically difierent compositions is quite large.

The properties of the various classes and of the numerous species within the several classes difier depending on the number, kind and amount of alloying elements and the proportion of carbon. The various alloying elements include manganese, molybdenum, nickel, chromium, vanadium, tungsten, silicon and others. Properties such as hot and cold workability, tensile strength, impact strength, corrosion resistance, high temperature hardness and various other valuable properties are obtainable. Those skilled in the metallurgical art are fully informed regarding the composition of the numerous classes and species and the properties of alloy steels having those compositions.

With plain carbon steels, high abrasion resistance can be obtained by the use of tungsten but that expedient can not be satisfactorily employed in the case of most alloy steels and there has long been a need for means whereby the abrasion resistance of alloy steels in general can be markedly improved While maintaining intact the other valuable properties of the base.

It is the principal object of the invention to supply that long-felt want.

In accordance with the invention, the alloy steel base contains from about 0.3 to about 1.50 per cent by weight of carbon and is hardenable to an R. C hardness of not less than about 53. With that base, there is incorported, for any particular carbon content within the range stat- 2 ed, a proportion of columbium carbide according to the following table.

Percent Car- Percent Oolumbium Carbon In excess of carbon bide to be added combined as ggl gg g Minimum Maximum 0. 30 About 3. 6 About 4. 5 O. 40 About 3. 4 About 4. 0 0.50 About 3.1 About 3. 6 0. About 2. 7 About 3.3 0.70 About 2. 6 About 3. 1 0. About 2. 4 About 2. 9 0.90 About 2. 2 About 2.7 l. 00 About 2.0 About 2. 5 1.10 About 1. 8 About 2. 4 1. 20 About 1. 7 About 2. 3 1.30 About 1. 6 About 2. 2 1.40 About 1.5 About 2. l 1. 50 About 1.5 About 2. 0

about 1 part by weight of carbon to about 10, parts by weight of columbium, to form the per.

cent of columbium carbide desired.

For any content of carbon in the base between the limits of about 0.30 per cent by weight to about 1.50 per cent by weight, the approximate minimum proportion of columbium carbide must be added to obtain the improvement in wear resistance. The maximum stated should not be exceeded to avoid disturbing other valuable properties includin transverse strength, impact strength, and ductility at room and elevated temperatures.

The carbon in the base alloy, as distinguished from carbon combined as columbium carbide, may be designated as matrix carbon. The advantages of the invention are not attainable by the use of matrix carbon without columbium carbide nor by the use of any or all proportions of matrix carbon and columbium carbide, but only by the conjoint use of certain restricted ranges of columbium carbide for a particular matrix carbon content, according to the table of correlated values above set forth.

The invention will be further described by reference to specific examples after first describing a test which has been found invaluable in measuring the wear resistance of steels.

The steels are machined into cylindrical specimens, /8" dia. x 1" long, heat treated and then ground on both ends. One end of the specimen is held by firm pressure of about lbs. against 120 grit alundum abrasive cloth, rotating at 1800 R. P. M. for six intervals of 5 seconds each. After each interval the specimen is cooled in water. The amount of metal ground away due to the 30 seconds of wear is measured with a Vernier micrometer to the nearest .0001" (tentlfif Anewiabrasive cloth -is used for each specimen but not for each time interval. By exceptional wear is meant Wear of not more than about one half that of the steel base, which is equivalent to stating that the improvement is about two fold and generally considerably more. For example, with a low carbon base (0.3 to 0.5% C) a wear of not exceeding about '80 tenths of an inch, whereas with a'high' carbon base (0.50 to 1.50% C) a wear ofnot exceeding about 40 tenths of an inch, may be obtained as measured by the above test.

Example 1 To a hot work steel containing 0.30 to 0.40% C, 3.5% Cr, 9.0% W, V, and the balance substantially iron, there was added 2.75 to 5.50% of colum bi'um carbide. These steels were cast into 2" sq. ingots, hammered to 73" sq., and

annealedl The'wear specimenswere then heated to 2175 F., oil quenched and tested as hardened and as drawn to 1050 F. The wear results folmom the above at i i ev en th t th arid? tion ofabout 3i8% columbium carbide' toan alloy steel containing .C, 3.50% Cr, 9.0% W, 2.5% V, balance substantially iron, a high degree of abrasive wear resistance is obtained. Moreover, this degree of abrasion resistance can be obtai without altering the other desirable properties of the steel base provided the percent or columbium carbide is kept within the limits of the invention. That is illustrated by ingot 6324; whicli ha good wear" resistance but poor transverse ductility and other undesirable qualit i'es.- For a base containing about 0.30 to 0.40 carbon, the Cb C should not exceed about 4.0% to 91.59% by weight.

Example 2 est wer amm r to a s; s nnealed, machined into wear test specimens, hardened from 1850? F. in oil, tested and then-drawn at 950 F. and again tested. Results are as fol. IOWSI From the above data it is evident that exceptionally good wear resistance is obtained on a 0.40% carbonghot,workisteel oi the type ,described by the addition of approximately 4.0% columbium carbide. Columbium carbide additions in -ainounts greater than about 4.00 per cent cause 7 low transverse ductility and other undesirable properties.-

' .E-mample 3 This example relates to an air hardening base containing 2.00 to 3.00% manganese, 1.00

' to 2.00% chromium, 1.00 to 2.00% molybdenum, 0.90 11) 1.20% carbon and the balance substantially iron.

To aspecific analysis .of the above type steel containing initially about 1.00% C, columbium and carbon were added in proportions to provide about 1.1, 2.2 and 3.3% columbium carbide respectively. These steels were cast into 1%" sq; ingots, weighing about 3 lbs., following which they were annealed, machined into wear test specimens, hardened from the most suitable hardening temperature, and then tested. The

wear in --tenthsis glven n the following table:

' Percent Percent Wear in R C ingot No. 7 Carbon Oolumbium in Base Carbide Tenths Hm dness 1.03 0 1,13 64 1. Q2 1. 15 112 64 l. 02 2.20 32 64 0. 9s 3. 32 20 (54 in the aboveaexamp'leg'the minimum and maximum percentages of columbium carbide should be-correlated with the carbon in the base'as fOllOWSI Percent C Percent 'Columbium in Base 7 at ide 0.90 About 2.2 to about 2.7 l. 05 About 1.9 to about 2.4 1. 20 About 1.7 to about 2.3

While ingot 102 has good wear resistant properties, it has poor transverse ductility which increases hot working difficulties.

"Other examples of the invention are as follows:

Example 4 The base represents a commercial shock-resistingsteel having a typical analysis range as follows:

alance substantially iron.

With the above, there is incorporated about 2.7 to about 4.0 per cent of columbium carbide correlated with the carbon in the base according to the invention.

Example 5 The base represents a shock resisting hot work steel having a typical analysis range as follows:

C About 0.40 to about 0.60 per cent Mn .About 0.25 to about 0.90 per cent Si About 0.25 to about 1.50 per cent Cr About 0.50 to about 1.80 per cent W About 1.00 to about 3.00 per cent V "About 0.20 to about 0.35 per cent balance substantially iron.

With the above, there is incorporated about 2.7 to about 4.0 per cent of columbium carbide correlated with the carbon in the base according to the invention.

Example 6 The base represents a commercial oil hardening non-deforming tool steel having a typical analysis range as follows:

C "About .80 to about 1.20 per cent Mn About 1.00 to about 1.80 per cent Si About 0.15 to about 0.45 per cent Mo About nil to about 0.40 per cent with or without one or more of the following:

Cr About .20 to about .90 per cent W About .40 to about .70 per cent V About .15 to about .25 per cent balance substantially iron.

With the above there is incorporated 1.7 to 2.9 per cent by weight of columbium carbide correlated with the carbon in the base in accordance with the invention.

Example 7 The base represents a commercial hot work steel having a typical analysis range as follows:

C About 0.30 to about 0.70 Mn About 0.15 to about 0.50 Si About 0.15 to about 150 Or About 1.25 to about 8.0 V About 0.25 to about 1.0

The above analysis includes 1.3 to 15.0% of tungsten or 1.5 to 5.0% molybdenum, or both, balance substantially iron.

With the above, there is incorporated from about 2 :6 to about 4.5 per cent by weight of columbium carbide correlated with the carbon in the base in accordance with the invention.

Example 8 The base represents a commercial hardenable stainless steel having a typical composition range as follows:

C About 0.30 to about 1.10 per cent Mn About 0.15 to about 0.50 per cent Si About 0.15 to about 0.50 per cent Cr About 12.5 to about 19.0 per cent with or without either or both of the following:

Mo About 0.25 to about 0.75 per cent V About 0.10 to about 0.30 per cent balance substantially iron.

With the above, there is incorporated from about 1.8 to about 4.5 per cent by weight of columbium carbide correlated with the carbon in the base in accordance with the invention.

Example 9 The base represents a commercial high carbon, high chromium tool steel having a typical composition range as follows:

balance substantially iron.

With the above, there is incorporated from about 1.5 to about 2.3 per cent of columbium carbide correlated with the carbon in the base in accordance with the invention.

Example 10 The base represents a commercial chromium nickel steel having a typical composition range as follows:

C About 0.40 to about 1.40 per cent Cr About 0.20 to about 1.50 per cent Ni "About 1.0 to about 4.5 per cent with or without one or more of the following:

W About 1.0 to about 2.5 per cent V About 0.10 to about 0.25 per cent balance substantially iron.

With the above, there is incorporated about 1.5 to about 4.0 per cent by Weight of colurnbium carbide correlated with the carbon in the base in accordance with the invention.

Example 11 The base represents a ball and bearing steel having a, typical composition range as follows:

C About 0.80 to about 1.10 per cent Mn About 0.20 to about 1.75 per cent Si About 0.15 to about 1.75 per cent Cr "About 0.35 to about 3.0 per cent balance substantially iron.

With the above there is incorporated about 1.80 to about 2.90 per cent by Weight of colurnbiurn carbide correlated with the carbon in the base in accordance with the invention.

Example 12 The base represents a commercial carbon vanadium Water hardening tool steel having a typical composition range as follows:

C About 0.60 to about 1.25 per cent Mn About 0.15 to about 0.35 per cent Si About 0.15 to about 0.50 per cent V About 0.08 to about 0.40 per cent balance substantially iron.

With the above there is incorporated about 1.6 to about 3.3 per cent by weight of colurnbium carbide correlated with the carbon in the base in accordance with the invention.

Example 13 The base represents a commercial valve steel having a typical composition range as follows:

C About 0.30 to about 0.50 per cent Mn About 0.20 to about 1.0 per cent Si About 2.0 to about 4.0 per cent Cr About 7.0 to about 9.0 per cent aeo ess 7 with or without one or more of the following:

Ni About 0.50 to about 1.0 per cent Mo About 0.25 to about 1.0 per cent W About 1.0 to about 3.0 per cent balance substantially iron.

With the above there is incorporated about 3.1 to about 4.5 per cent by weight of columbium carbide correlated with the carbon in the base in accordance with the invention.

This application is a continuation-in-part of application Serial No. 529,366, filed April 3, 1944, now abandoned.

What is claimed is:

1. The combination of about 1.5' to about 4.5 per cent by weight of columbium carbide, with an alloy steel base, said base containing not less than about, 70 per cent by weight of iron, about 0.30 to about 1.50 per cent by weight of carbon and being hardenable by quenching to a Rockwell C hardness not less than about 53, the columbium carbide being composed of columbium and carbon in the weight ratio of about 10 to 1, and the minimum and maximum percentages by weight of columbium carbide being correlated with the per cent by weight of carbon in the hardenable base as follows:

Per cent by weight of Colurnhium carbide Per cent by weight of Carbon in Minimum Maximum the base About 3.0 to about 1.5 About 0.30 About 3.4. to about 4.0 About 0.40 About 3.1. to about 5 6....-.. About 0.50 About 2 7. to about 3.3 About 0.60 About 2 0 to about 3.1. About 0.70 About 2 4 to about 2 9 About 0.80 A bout 2 to about 2 7. About 0.90 About 2 to about 2 5. About 1.00 About 1 to about 2 4 About 1.10 About 1 7. to about 2.3. About 1.20 About 1 G. to about 2 2- About 1.30 About 1 5 to about 2 l-.- About 1.40 About 1.5 to about 2.0 About 1.50

2. The combination of about 1.7 to about 2.7 per cent by weight of columbium carbide with an air hardening alloy steel base containing about 0.90 to about 1.20 per cent by weight of carbon and being hardenable by quenching to a Rockwell C hardness of not less than about 53, said base also containing about 2 to 3 per cent by Weight r Per cent by weight of Columbium Carbide Per cent by Weight of Carbon in Minimum Maximum the Base About 2.2 to about 2.7. About 0.9 About 2.0. to about 2.5 About 1.0 About 1.8 to about 2.4 About 1.1 About 1.7. to about 2.3 About 1.2

3. The combination of about 2.6 to about 4.5 per cent by weight of columbium carbide with a hardenable hot work alloy steel base containing about 0.30 to about 0.70 per cent by weight of carbon and being hardenable byquenching o a Rockwell C hardness of not less than about 5 said base also containing, about 0.15 to abo t 0.50 per cent by weight of manganese, about 0.1 to about 1.50 per cent by weight of silicon, about 1.25 to about 8.00 per cent by weight of chromium, about 0.25 to about 1.0 per cent by weight of vanadium, and an element selected from the group consisting of tungsten in the amount of about 1.3 to about 15.0 per cent by weight and molybdenum in the amount of about 1.5 to about 5.0 per cent by weight, balance substantially iron, the columbium carbide being composed of columbium and carbon in the weight ratio of about 10 to 1, and the minimum and maximum percentages by weight of columbium carbide being correlated with the per cent by weight of' carbon in the base as follows:

hardenable non-deforming oil-hardening alloy steel base containing about 0.80 to about 1.20 per cent by weight of carbon and being hardenable by quenching to a Rockwell C hardness not less than about 53, said base also containing about 1.00 to about 1.80 per cent by Weight manganese, about 0.15 to about 0.45 per cent by weight silicon, about 0.15 to about 0.40 per cent by weight molybdenum. about 0.20 to about 0.90 per cent by Weight chromium, about 0.40 to about 0.70 per cent byweight tungsten, and about 0.15 to about 0.25 per cent by weight vanadium, said chromium, tungsten and vanadium being optional, the columbium carbide being composed of columbium and carbon in the weight ratio of about 10 to 1, and the minimum and maximum percentages by weight of columbium carbide being correlated with the per cent by weight of carbon in the base as follows:

Per cent by weight of Columbium Carbide Per cent by weight of Carbon in Minimum Maximum the Base About 2.4 to about 2.9 About 0.8 About 2 2 About 0.9 About 2 0.- About 1.0 About 1.8 About 1.1 About 1.7 to about 2.3 About 1.2

MAURICE c. FETZER. CARL B. POST.

REFERENCES CITED The following references are of record in the file of this patent:

FOREIGN PATENTS Number Country Date 457,760 Great Britain Nov. 30, 1936 507,983 Great Britain June 23, 1939