A method to improve the machinability with constantly posture of the hardness of steel clasps with a carbon content of 0 05 to 0 65, by cold forming

摘要

1,084,305. Improving physical properties. SCREW & BOLT CORPORATION OF AMERICA. Sept. 7, 1964 [Sept. 5, 1963], No. 36666/64. Heading B3V. [Also in Division C7] A method of improving the machining and drawing characteristics of steel comprises tensioning the steel beyond its yield point and then cold working it to final form. Bar-stock may be tensioned to produce a permanent extension of 6-20%, after which it may be cold drawn. Before being drawn the bar may be pickled, worked and limed, and after drawing it may be straightened. If the bar is furnacestress-relieved to improve the yield strength, elongation and reduction in area, a further straightening operation will be needed. For even higher physical properties, before stretching the bar is annealed, normalized or quenched, and tempered; it may also be surface-hardened in a furnace with a controlled atmosphere. A number of examples are given in which are listed the treatment given and the physical and machining properties of the material. Steels having the following composition are listed:-