Structural Steel For Through-Surface Hardening

摘要

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 1.5; boron—not more than 0.007; copper—not more than 0.3; aluminum—0.03-0.1; nitrogen—not more than 0.1; titanium—not more than 0.4; vanadium,—not more than 0.4; zirconium—not more than 0.4; niobium—not more than 0.1; tantalum—not more than 0.1; calcium—not more than 0.03; sulphur—not more than 0.035; phosphorus—not more than 0.035; iron and unavoidable admixtures—rem., with ideal diameter determined by the following mathematical formula:;Dkp.=K·√C·(1+4.1·Mn)·(1+0.65·Si)·(1+2.33·Cr)·(1+0.52·Ni)·(1+0.27·Cu)··(1+3.14·Mo)·(1+1.05·W)·[1+1.5(0.9−C)]·(1−0.45C′)·(1−0.3Ti)·(1−0.35V)·(1−0.25Al),;Where:
Dcr is the ideal diameter, mm,K is the coefficient whose value depends on the actual austenite grain size according to the ASTM, GOST5639; C, Mn, Si, Cr, Ni, Cu, Mo, W are components, weight %, contained in the austenite solid solution at the final heating temperature preceding hardening cooling, [1+1.5(0.9−C)] is the multiplier taken into account only if boron is present in steel in the amount of 0.002-0.007 weight %; C′, Ti, V, Al are components, weight %, not contained in the austenite solid solution, but present in the form of structurally-free secondary carbonitride phases at the final heating temperature preceding hardening cooling, C′ is carbon in the excessive cementite of hypereutectoid steel.

主权项

1. Structural steel for through-surface hardening containing carbon, manganese, silicon, chrome, nickel, copper, aluminum , titanium, vanadium, niobium, tantalum, calcium, sulphur, phosphorus, iron and unavoidable admixtures, with a distinction that it additionally contains molybdenum, tungsten, boron, nitrogen and zirconium with the following component ratio, weight %:Carbon.15-1.2Manganesenot more than 1.8Siliconnot more than 1.8Chromenot more than 1.8Nickelnot more than 1.8Molybdenumnot more than .5Tungstennot more than 1.5Boron.not more than .007Coppernot more than .3Aluminum.03-.1Nitrogennot more than .1Titaniumnot more than .4Vanadiumnot more than .4Zirconiumnot more than .4Niobiumnot more than .1Tantalumnot more than .1Calciumnot more than .03Sulphurnot more than .035Phosphorusnot more than .035Iron and unavoidable admixtures—remaining.