Abstract: A size hardening heat treatment process for steel parts of a plate, cylindrical or spherical shape and using low or specified hardenability steel compositions which are through surface heated and very rapidly quenched to produce case hardening of the part. A set of graphs are provided which depict the relationship between the depth of hardening and the dimension of the part for each of a series of critical, i.e., ideal diameter values which allow producing a depth of hardening of a particular part by a proper selection of the DI value of the part. The DI values are calculated by a formula which allows a range of DI values to be created by varying the components of the steel as set out in the formula. The formula also insures a fine grain size to be created by the process to prevent cracking by the very rapid quenching required. A list of elements allowed in the steel but limited by a % mass set out for each component.

Abstract: The invention refers to development of chemical composition of perlite-class structural steels hardened by thermal treatment—through-surface hardening (TSH). The technical result is to obtain low and specified hardenability 3rd generation LH (SH) steels with a finer austenite grain ##11-13 GOST5639 (ASTM), even more stable preset hardenability (DI) with a substantially smaller To obtain a finer austenite grain and more stable hardenability—DI, with a substantially smaller deviation range and hardened layer depth directly obtained on parts subjected to TSH, as well as the possibility of machining thinner, smaller and other parts with the through-surface and through-thickness hardening. To achieve the technical result, structural steel was proposed for through-surface hardening with the following components ratio, weight %: carbon—0.15-1.2; manganese—not more than 1.8; silicon—not more than 1.8; chrome—not more than 1.8; nickel—not more than 1.8; molybdenum—not more than 0.5; tungsten—not more than 1.

Abstract: A process for making desired low (LH) hardenability steels in an electric arc or, induction furnace, which is loaded with metal charge consisting of iron, carbon, alloy, scrap with a specified maximum content of manganese, silicon, chrome, nickel and copper, providing for the final content of each of them of not more than 0.1 weight % followed by carburization in a ladle or ladle furnace, the melt then deoxidized in the ladle or ladle furnace with aluminum (1.0-2.3 kg/t), titanium or vanadium in order to achieve the desired low hardenability DI. The invention makes it possible to obtain better mechanical properties and stable hardenability characterized by the particular desired DI.

Abstract: The invention refers to hardening thermal treatment of the perlite-class steel. The technical result is to obtain a finer austenite grain ##11-13 GOST5639 (ASTM), more stable hardenability level (DI), with a substantially smaller deviation and which strictly corresponds to the depth of the hardened layer obtained directly on parts subjected to thermal treatment, as well as the ability of treating thinner, smaller and other parts with the through-surface and through-thickness hardening. To achieve the technical result, a method for thermal treatment of parts made from low (LH) and specified (SH) hardenability structural steel is proposed for parts shaped as a sphere, cylinder, plate, including through-surface hardening by through-surface heating of the part or its effective cross-section, up to the temperatures of austenitization and cooling with a liquid refrigerant at the rate of more than 40,000 kcal/m2.h.0C.

Abstract: The invention refers to metallurgy, in particular to making low (LH) and specified (SH) hardenability steels in electric arc, induction furnaces or oxygen converters. A metallurgical unit is loaded with metal charge consisting of iron carbon alloy, scrap with a specified content of manganese, silicon, chrome, nickel and copper, providing for the final content of each of them of not more than 0.