等温淬火对700MPa冷轧TRIP钢0.15C-1.5Mn-1.4Si-0.03Nb-0.03Ti-0.005N力学性能的影响

Effect of Austempering on Mechanical Properties of 700 MPa Cold Rolled TRIP Steel 0.15C-1.5Mn-1.4Si-0.03Nb-0.03Ti-0.005N

试验钢由50kg真空感应炉冶炼，锻造成60mm板坯经l250℃均匀化处理后热轧至4him板，再冷轧至1mm板。研究了试验TRIP（转变诱发塑性）钢冷轧板820℃ 3min淬火时等温淬火温度（350—450℃）和保温时间（1～10min）对钢的组织性能的影响。结果表明，奥氏体等温淬火工艺对试验钢的力学性能有显著影响；最佳的等温淬火工艺为820qc3min＋400℃5min水冷，该钢的抗拉强度与总伸长率分别为766MPa与37％，即强啦积达28．34GPa·％；10nm级Nb（cN）粒子的大量析出是造成该试验钢强度显著提高的主要原因。

Test steel is melted by a 50 kg vacuum induction furnace, forged to 60 mm slab, homogenized at l 250 ℃ then hot-rolled to 4 mm plate and cold rolled to 1 mm sheet. The effect of austempering temperature （350 - 450 ℃ ） and holding time （ 1 - 10 min） on structure and mechanical properties of 820℃ 3 min quenched test TRIP steel cold-rolled sheet has been studied. Results show that the effect of process of austempering on mechanical properties of test steel is obvi- ous; the optimum austempering process is 820 ℃ 3 min ＋400 ℃ 5 min, water cooling, the tensile strength and total elon- gation are respectively 766 MPa and 37% , i.e. the strength-plasticity product is 28.34 GPa % ; a lot of Nb （CN） parti- cles precipitation with 10 nanometer size is main factor to increase the strength of test steel.