具有TRIP效应低屈强比贝氏体基超高强钢研究

Study on Low Yield Ratio of Utra-high-strength TRIP-aided Bainitic Steel

对C-Si-Mn系TRIP钢采用等温退火工艺,得到具有TRIP效应贝氏体基高强钢。结果表明,TBF钢的组织主要由无碳化物贝氏体板条束、块状残余奥氏体、板条束间的薄膜状残余奥氏体及少量的回火马氏体组成。在连退过程中,贝氏体等温温度对TBF钢的组织和性能影响显著,当贝氏体等温温度为300℃时,TBF钢具有低屈服强度（789 MPa）、高抗拉强度（1241 MPa）以及良好的伸长率（16.6%）。等温300℃时,屈服强度的降低主要是因为80~190 nm的无碳化物贝氏体板条的生成。经过XRD测定,其残余奥氏体含量为12.04%,残奥含碳量经过测算为1.4%。稳定的块状残余奥氏体和无碳化物贝氏体板条有利于韧性的提高,相反,马氏体应该减少或避免。

A newly development C-Si-Mn bearing high strength bainitic sheet steel which was associated with the transformation-induced plasticity （TRIP） of retained austenite obtained by isothermal annealing. The steel mainly consists of carbon-flee baintic ferrite lathe, inter-lath retained anstenite films, stable blocky retained austenite and little tempering martensite. When isothermal holding at 300℃, the tensile strength of ＂TRIP type bainitesteel＂ possesses high tensile strength of 12401 MPa, low yield strength of 789 MPa and large total elongation of 16.6%. The decreased yield strength can mainly contribute to the carbon-free baintic ferrite lathe whose width changes from 80 nm to 190 nm, when isothermal temperature is at 300℃. The XRD energyspectrum of the steel at 300℃ isothermal temperature indicates that the volume of retained anstenite is 12.04%, and the carbon content of retained anstenite is 1.4%. The increasing tough depends on the stabler blocky retained austenite and carbon-free baintic lath, whereas, the martensite should be avoided.