US1359238A - Process of treating steel - Google Patents

Description

NORMAN C. EINWECHTER, OF PHILADELPHIA, PENNSYLVANIA.

PROCESS OF TREATING STEEL.

No Drawing.

To ail whom it may concern:

Be it known that I, NORMAN C. EiNwnoi-I- 'rnn a citizen of the United States, residing in 1 hiladelphia, Pennsylvania, have invented Processes of Treating Steel, of which the following is a specification.

In the use of rivet sets, drills, cutting chisels and the like such as are employed in pneumatic tools, I have noted that these usually failed by reason of the crystallization occurring in their structure due to the peculiar and oft repeated stresses to which they were subjected. This was noticeable not only in alloy steels, where, in the case of rivet sets for example, it was found that these would invariably fail before more than five hundred rivets had been headed, but also, and particularly, in the case of ordinary carbon steels.

One object of my invention therefore isto provide a method or process for so treating .alloy steels and more particularly vanadium steel, as to materially increase the useful life of tools of the above class made therefrom. In carrying out this invention I so operate on the steel as to render its structure substantially homogeneous throughout and particularly to prevent the existence in the body of a tool made from it, of stresses such as would be due to irregular or uneven heat treatment.

According to my invention, in a typical case I preheat a tool of alloy steel evenly and slowly to 1250 F, moving it about on the floor of the furnace during such operation so as to insure that its entire mass is brought to the desired temperature. An alloy steel which I have employed in carrying out my invention would have a composition as follows: Vanadium about 0.20 of 1%, carbon .60 to .80 of 1'71, and manganese about 0.25 of 1%. 'hen this condition exists, it is transferred to a second furnace, where it is heated to a temperature of from 14.30 to 1440 hi, c. from thirty to forty dcarecs above 1400 which the cri ical temperature of the steel under co. the critical temperature being that to which it should be brought in order that it may thereafter be properly harden. l. steel reaches this temperature its critical temperature and or. uniform distribution of heat its entire mass, it is quenched i in; a temperature of about i is allowed to remain until it has Specification of Letters Patent.

Patented Nov. 1.6, 1920.

Application filed May 5, 1919. Serial Nd, 294,662.

appreciably vibrate, when it is at once removed to an oil bath and subjected to an appropriate tempering treatment forming no part of my invention.

In explanation of the above process I would point out that for the particular steel above referred to, 1400 I. has been found to be the critical temperature to which it should be heated in order that it .may thereafter be suitably hardened, and

my invention resides in the discovery that by raising its temperature from 30 to 40 above this critical point prior to the quench ing operation, the innermost portions of the body of said steel as well as its outer parts, will have the critical temperature of 14:00 when the quenching actually takes place. Under these conditions the whole mass of steel is free from injurious stresses.

If on the other hand, the body of steel is heated to 14:00 as has been customary, and is then-quenched, its outer portions will unavoidably cool in the interval between its removal from the furnace and its entry into the Water, so that the parts of its body immediately adjacent its surface have a temperature below H00 while its interior is still approximately at 14.00 withthe result that those stresses are set up which I have found cause the rapid failure of the finished tools, when used in pneumatic apparatus prior to my invention. \Vhere rivet sets as ordinarily treated would invariably fail before more than five hundred rivets had been headed, I find that when subjected to my treatment they will almost without exception head from twenty-' to twenty-five thousand'rivets, and in extreme cases, as many as one hundred and twenty-five thousand rivets have been headed before failure of the tool has occurred. the results attained being dependent upon the expertness of the operator in treating the tool according to my invention.

It will be understood that while in the above description I have referred particularly to rivet sets as benefiting by my invention, the latter is equally and advantageously applicable to all tools subjected to vibratory or rapidly alternating stresses such as exist in pneumatic tools under conditions of use and which have been found in the past to cause rapid crystallization of the structure of the tools employed.

It is further to be noted that while I have referred to l4 30 l0 F. as the temperature yent-ion, the essence of which consists in heating the body'of steel under treatment from twenty to forty degrees above its socalled critical point as above defined which point would vary with the composition of the particular steel under treatment.

I claim:

1.. The method of treating vanadium steel which consists in heating it slowly to a temperature of from 1430 to 1440 F." quenching it in water at a temperature 0 60 F. until vibration ceases; and then placing it in an oil bath. T

2. The method of treating vanadium steel which consists in slowly heating it to 1250 F. in one furnace; transferring it to a second furnace and heating it therein to a temperature of from 1-130 to 14:40 E; quenching said steel in water until vibratlon has ceased; and thereafter transferring it to an oil bath.

3. The method oftreating a tool of vanadium steel which consists in heating it evenly and slowly to a temperature of about 1250 F.; thereafter increasing its temperature to ll-1440 F.; and quenching it when its entire mass has a temperature of about 1400 F.

In witness whereof I aflix my signature.

NORMAN C. 'EINVVEGHTE-R.