US979113A - Heat treatment of steel. - Google Patents

Description

UNITED STATES PATENT OFFICE.

SAMUEL WALES, F MUNHALL, lPENNSYLVANIA, ASSIGNOR T0 CARNEGIE STEEL COMPANY, OF PITTSBUBG, PENNSYLVANIA, A; CORPORATION QFJNEW JEBSEY.,

HEAT Tnnermnnr or STEEL.

1210 Drawing.

To all whom it may concern:

7 scription.

Be it known that I, SAMUEL S. WALES, of Munhall, Allegheny county, Pennsylvania, have invente a new and useful Improvement in Heat Treatment of Steel, of which the following is a full, clear, and exact de My invention .is designed to provide an improved method of heat treatment of steel, whereby a ,more uniform strength is obtained throughout the piece, and is particularly designed for armor or vault plates or-deck plates, though it may be applled to plate, the ingot is cast in the usual way, forged, annealed, then carburized on its face, then usually 'reforged, and then fibered by the usual process. The late is then' sometimes toughened by furt or treatment, and is thenin a condition for final water-hardening. The heat treatments for such plates and other heat-treated steels are uniform over the, extent of the plate and take no hecount of the variationsin chemical composition of the various parts of the plate,-

caused by segregation of-its contained metallo'ids during cooling'and solidifying of the ingot.- The carbon is most liable to segreation, and other elements may be calculated in carbon equivalents. This segregation takes place to a greater extent in the top portion of the ingot than in the lower portion, and where the bottom end or top end of the plate is hereinafter mentioned I refer to that portion of the plate which comes erably roughly in proportion tothe segre.

from the bottom portion or from the top gar-Hon, of the ingot as the case may be. 7 y subjecting the whole plate or portion to be treated to'a uniform heating, great difierences in tensile strength between the top and bottom of the'ingot may be developed;

and I have discovered that such differences may be largely reduced and-possibly eliminated by raising the plate to a temperature which varies between the two ends and prefgation.

In practice a "great improvement is made in the plate by modifying the last annealing process and varying the heat of difi'erent parts of the plate. *ThusI first preferably raise the plate to a'temperature between 800 and 900 degrees C and quench with water or other cooling liquid to a temperature below 300 degrees; The

laced in the furnace, and the eat so reguated therein that the end of the plate which is subject to the greater segregation, will be raised to a temperature higher than the other end of the plate. The variation in temperature of one end of the plate'from the other may be accom lished 1n any desired manner, for examp e, the temperature of one end of the furnace-in which the plates are heated, may be raised or lowered abovev orbelow that of the. opposite end to a degree necessary to give the desired difference in temperature in the opposite ends of the plate,by a-proper manipulation of the air and gas valves used on such furnaces. This tem erature may be calculated by many wel -known methodsto attain a certain desired tensile strength. The average ofthese temperatures is preferablycbetween 500 and 700 degrees (3., and the dilf er'ence in temperature between the twoends may be as high as 150 degrees. The plate is then cooled as desired; In a test on a plate,

twenty feet in lengthshOWing such a segre'gation in carbon that -the content was .37 at the top end and .27 at the bottom end,- was subjected to the varying heat treatment just described with an annealing temperature of about 620 degrees at the top end and about 520 degrees at the bottom end; and

v Specification of Letters Patent. Patented Dec, 20, 1910, I Appfication filed April 21, 1908. Serial No. 428,307.

late is then the tensile strength of test pieces taken from these ends did not differ over one per cent.

Theadvantages of my invention will be ap reciated by those skilled in the art. The di erent strength'in different parts of the plate or portion to be treated resulting from the uniform heat treatment heretofore given is overcome, and the platemade substantially uniform or the variation in strength greatly reduced b the variation in the temperature imparte to the various parts. My

invention does not add to the cost of production, but does add materially to thevalue of the plate making its strength more uniform in the different parts.

Many variations ma 'be made in the above described treatment 0 the steel without'de parting from my invention, since What I claim 'is: .1. The method of metalloids in different proportion different parts thereof, consisting in h ating the treating steel contalning' lateand raising one part of the portion to iie-treated to a different temperature from that of another portion at the same. depth. Y 2. The method of heattreating steel, consisting in'heating the plateor portion'to be treated and varylng the heat of-the different parts accordin 'to the proportion of metal loids containe therein.

e3. The'method of heat-treating steel havin different proportions of metalloids in di er'ent parts thereof, consisting in heatn'g the plat'e and raising those portions contamin .a greater proportion of metalloids to a higher heat than-those portions containmg alower proportion of metalloids.

4. The method of treatingsteel, consisting I in heating a plate to a hardening temperaformly heatin ture, then ture, then quenching it,- and, then tin-unithe length. of the plate to temperatures etween 500 and 700 degrees cent1grade, and then cooling the same.

5. The method of treating steel, consisting. in heating a plate to a hardening temperaquenching' it, then heating it to diflierent temperatures at different portions of the plates with relation to the difference in composition caused by segregation.

6. The method of treating steel, consisting in heating a plate to a hardening temp'eratu're, then quenching it, then heating the different portions of the plate to temperatures varymgdirectly to the proportions of carbon contained 1n the said dliferent portions of said plate.

7. The method of treating steel, consisting in annealing a plate, in

hyheating the different portions of the plate to temperatures between oOOdegrees and 700 said different portionsheat at temperatures varying directly to the proportion of 'car-.

degrees centigrade, being subjected t0 bon'contained therein, and then cooling the same. a I v 8. The method .of treating steel plate, in which the component elements are more highly segregated at one end than at the which the various component elements have become segregated,

other, which consists in heatingthe plate to tion of its face.

In testimony whereof, I have hereunto set my hand. I

' SAMUEL s. WALEsL Witnessesi D. T, Jon'ns, C.-v L. WILsoN,

portion of its face 7