US 1927986 A
Description (OCR text may contain errors)
Sept. 26, 1933. s. N. LEVY 1,927,986
ALLOY TOOL STEEL Filed Feb. 26,- 19:52
Patented Sept. 26,. 1933 UNITED STATES PATENT? OFFIC'IE ALLOY TOOL STEEL Sylvan N. Levy, Arden, Del. Application February 26, 1932. Serial No. 595,396
toughness, which properties are necessary in such tools. This application is filed as a continuation in part of my co-pending application Serial No. 531,851, filed April 21, 1931, for Alloy tool steel.
One object of my invention is to provide an alloy steel for use in the manufacture of metal, stone, and wood cutting tools which has a high elastic limit or ductility when heat treated for tool service and which at the same time will have a higher tensile strength than the carbon steels or alloy tool steels now generally in use.
A further object of my invention is to provide an alloy tool steel which possesses good forging qualities including lack of sensitiveness to what is termed cold shortness or hot shortness and which will withstand the forging and upsetting operations to which tool steels are subjected when made into tools such as chisels, caulking tools, paving breaker steels, and the like.
Still another object is to produce an easily machinable tool steel which may be annealed to obtain a relatively low Brinell figure without causing spheroidization and its accompanying failure to harden under proper heat treatment.
Still another object of my invention is to provide a steel which will harden at the temperatures generally in use in the hardening of plain carbon tool steels but which may be forged and quenched at materially increased temperatures so as to allow a wider latitude in the heat treating operations than is permissible with carbon tool steels.
Other objects will be apparent from a consideration of the specification and claims.
In steels to be employed in tools of the type of pneumatic, electric hammer, or other pistonoperated chisels, rivet sets, rivet busters, paving breaker steels, back-out punches, etc., or in machines of the type of machine punches, etc., a steel showing a high elastic limit or ductility is essential. The powerful blows of the modern pneumatic hammers have required steels which will transmit the force of the stroke without breaking at the weaker sections of the tool. It has been found impractical to change the shank design of such tools as chisels and rivet sets in order to strengthen the design of the tools as the hammers have increased in efficiency, on account of the difficulties encountered in large plants where the shank standards have been maintained the same since the pioneering stage of the pneumatic hammers. For this reason, the improvement in the tool steels for use in conjunction with such tools has become of prime importance.
The higher the elastic limit of the tool steel, the
better will be the transmission of the blow from the piston end of the tool through the shank and body to the working end of the tool, and the breakage which occurs at the neckor weakest with such tools as machine punches, back-out punches, etc., steels used in this work must have a relatively high tensile strength.
In the drawing:
Figure 1 is a side elevation of a pneumatic rivet set; and
Figure 2 is a plan view thereof.
The pneumatic rivet set is cited as perhaps the most typical case to illustrate the problems which are involved in connection with construction and demolition tools used in hammers of various types, which problems are overcome by the steel of the present invention. In this type of piston-operated tool which includes chisels, rivet sets, rivet busters, paving breaker steels, back-out punches, etc., there are always points of weakness which cause breakage ,of the tools. In the rivet set shown in the drawing, A represents the neck of the tool, B the piston end of the rivet set, and C the cup thereof. Steels generally in use for this type of tool show quick failure at A, resulting in breakage of the tool at this point, due to fatigue strains set up through repeated blows of the piston in the hammer at point marked B. When rivet sets are manufactured from the steel disclosed herein, the fatigue strains described do not result in the breakage of the tool at the neck.
In the steels generally employed, there is a tendency for the shank of the rivet set to spread, causing it to stick in the hammer or eventually break the set at the point marked B when the rivet set indents on the piston end.' This is particularly true when the riveter points his piston' as is common practice, that is to say when the piston is ground to a point giving more rapid and lively rebound in the hammer. With the steel of the .presentinvention, due to grain compactness and through-hardening properties, the piston end B of the rivet set cannot be indented in service even when the riveter points hi's piston.
Steels ordinarily in-use in rivet sets and the like have a tendency to mush in" at cup C when repeatedly driven against hot rivets, a fault not found in the steel of the present invention with which due to grain compactness and throughhardening qualities the cup life at point C is materially lengthened.
With toolsteels which are subject to forging operations, such as chisels, caulking tools, pav ing breaker steels, etc. it is essential that they possess good forging qualities which include lack of sensitiveness to what is termed cold shortness on hot shortness. Tool steels generally show a tendency to split when forged at low temperatures such as 1000 F. or to break down in structure when forged as high as 2000 F. to 2200 F. When collars are upset on tools, such as chisels, paving breaker steels, etc., the tendency is to break down the grain structure at the collar to such an extent that the later heat treatment fails to correct this damage done in forging, and breakage in service occurs at this point. This is particularly true of the chrome tool steels and thehigh silicon (1.50%2.50% and high manganese (.50%-1.00%) as well as with the carbon tool steels.
Furthermore, it has been the general experi- 7 once of tool steel manufacturers that the alloy steels, and especially the silicon-manganese'steels with silicon about 1.80% and manganese about .75%, require very careful annealing at controlled heats. When annealed at temperatures and under conditions which will produce low-hard down the spheroidized structure, to either re-roll or re-hammer the stock to smaller sizes.
The steel of the present invention has a high elastic limit when heat treated for tool service and at the same time has a high tensile strength. This tool steel also possesses good forging qualities, for example there isa lack of sensitiveness to cold shortness or hot shortness, and there is no tendency for the tool to split when forged at a low temperature such as 1000 F. or to break down in structure when forged at as high a temperature as 2000 to 2200 F. The steel will also withstand the up-setting operations to which the tool steel is subjected when made into tools of the types hereinbefore mentioned. This tool steel may be easily annealed at as low a temperature as 1450" F. to a hardness as low as 165 Brinell without causing spheroidization with the subsequent failure to harden under proper heat treatment. This is in contradistinction to other steels, such as those of higher silicon content, which have air-hardening qualities. The soft condition of the steel of the present invention in the annealed state makes it comparable in fast cutting qualities to ordinary machinery stock. This is of tremendous advantage to the toolmaker, and-lowers the cost of production of tools as compared to those made of the tool steels commonly used.
My invention contemplates a new alloy tool steel in which there is present both molybdenum ,and vanadium in a carbon tool steel containing limited proportions of silicon and manganese. The amounts of molybdenum and vanadium present may vary considerably. For example, the molybdenum may be present from .15% to 5.00% and the percentage of vanadium may vary from .10% to 2.00%, but the combined amount of molybdenum and vanadium may not be less than 25% without losing all the desirable qualities of the steel. Since the .molybdenum and vanadium in combination give the carbon steel a tremendously increased through-hardening property, it is possible in the steel of the present invention to reduce materially the carbon content in a steel for a given purpose without lowering the hardness obtainable while at the same time the tensilestrength will be increased. It will be desirable to keep the manganese within the percentage of .15% to 45% found in the ordinary carbon tool steel. Furthermore, in the steel of this invention, the percentage of silicon is increased somewhat over the proportion normally found in plain carbon tool steels. Since as the silicon increases the grain growth rapidly develops with resultant brittleness and reduced hardening qualities, it is desirable to keep the percentage of silicon low, particularly in steels to be used for battering tool purposes. In no instance is the percentage of silicon carried above 90%.
The ranges of the percentages which may be employed in the steel of the present invention are: carbon 40% to 2.00%; manganese .15% to .45%; silicon .15% to .90%; molybdenum .15% to 5.00%; and vanadium .10% to 2.00%. As before pointed out, the combined percentage of molybdenum and vanadium wil not be below .25%. The remainder of the alloy will be made up of iron with low percentages of .sulphur and phosphorous. By varying the percentage of the elements within the limits given, varying qualities of the steel may be obtained approximating that of the most desirable for demolition and construction tools given in the specific ,example. For instance, if the carbon is above .60%, the minimum limits of the other elemnts may be used to produce a tool steel of excellent qualities. An example of an analysis of a steel which possesses qualities for use in ordinary tool work and in piston-operated demolition and construction tools where the fatigue strains are not too severe is as follows: carbon .45% to 1.25%; manganese .25% to .45%; silicon .40% to .80%; molybdenum .15% to 5.00%; and vanadium .10% to 2.00%, although in most instances a molybdenum content of .80% to 1.10% and a vanadium content of .20% to 30% will be employed. Generally, however, for a steel for piston-operated demolition and construction purposes,the carbon in the steel will be between .45% and .70% the manganese will be between .25% and .40%; the silicon between .40% and 170%; the molybdenum between .80% and 1.10% and the vanadium between .20% and 30%.
In a typical case, a steel of the following analysis has proved to possess exceptionally satisfactory properties for'use in conjunction with construction and demolition tools:
Element Percentages Tolerance Percent The remainder is made up of iron with the usual small percentages of impurities such as sulphur and phosphorus.
-.70% with a tolerance of 12.10% without materially changing the properties of the steel.
The tool steel described not only the desirable physical properties set forth but also has a further advantage relative to the hardening process. As most tools of the types mentioned have been made in the past from carbon steels which harden at low temperatures-1400 F. to 1550" F.it is desirable to provide an alloy tool steel which will harden in water or brine at a low temperature approximating that of the carbon steels, and yet possess the essential qualities needed in tools of this type and not found in carbon tool steels. Since the steel of the present invention hardens at these low temperatures, no particular hardening instructions need be 'given to the unskilled blacksmiths who usually rially increased over that permissible with the carbon tool steels. In plants properly equipped for accurate control of the hardening heats and now using alloy steels which harden at materially higher heats in place of the carbon steels for piston-operated construction and demolition tools of the type mentioned, the steel of the present invention will furnish considerable economy in time, fuel, and furnace-wear "due to its lower critical point.
ganese .25% to .45%, silicon .40% to .80%.
molybdenum .15% to 5.00%, and vanadium 10% to 2.00%, the remainder being iron with low percentages of sulphur and phosphorous.
4. Piston-operated demolition and construction tools made from the alloy steel as set forth in A I claim 3.
5. An alloy tool steel having an analysis substantially as follows: carbon .45% to 310%, manganese .25% to 10%, silicon .40% to 110%, molybdenum 30% to 1.10%, and vanadium 30% to .30%, the remainder being iron with low percentages of sulphur and phosphorous.
6.. Piston-operated demolition and construction tools made from the alloy steel as set forth in claim 5.
7. An alloy tool steel having an analysis substantially as follows: carbon .50%, manganese .30%, silicon 50%, molybdenum 1.00%, and vanadium .25%, the remainder being iron with low percentages of sulphur and phosphorous.
8. Piston-operated demolition and construction tools made from the alloy steel as set forth in claim 7.
9. An alloy tool steel having an analysis substantially as follows: carbon 50%, manganese 30%, silicon 170%, molybdenum 1.00%, and vanadium .25%, the remainder being iron with low percentages of sulphur and phosphorous.
10. Piston-operated demolition and construction tools made from the alloy steel as set forth in claim 9.
11. An alloy steel having an analysis as follows: carbon .40 to 115%, manganese .15 to .40%, silicon .15 to .2%, molybdenum .15 to 50%, vanadium .10 to .15% and the remainder being substantially all iron.
. SYLVAN N. LEVY.