FIELD: metallurgy.
SUBSTANCE: invention relates to the field of metallurgy, namely to steel for forging mechanical parts of a vehicle or an engine. Steel contains following elements, in wt.%: 0,15≤С≤0,22, 1,6≤Mn≤2,2, 0,6≤Si≤1, 1≤Сr≤1,5, 0,01≤Ni≤1, 0≤S≤0,06, 0≤P≤0,02, 0≤N≤0,013, if necessary, at least one element selected from a group: 0≤Al≤0,06, 0,03≤Mo≤0,1, 0≤Сu≤0,5, 0,01≤Nb≤0,15, 0,01≤Ti≤0,03, 0≤V≤0,08 and 0,0015≤B≤0,004, the rest is iron and inevitable impurities. Steel microstructure, when expressed in levels of surface percent content, contains, in total, residual austenite and martensitic-austenitic islets in the amount in the range between 1% and 20%, martensite in the amount in the range between 0% and 10%, while remaining microstructure is bainite, which is at least 80%. The fractional concentration of grain boundaries of bainite at the angle of disorientation of 59.5° is at least 7%.
EFFECT: high mechanical properties and moldability are provided.
20 cl, 3 dwg, 4 tbl
