V-Ti微合金钢的组织性能及相间析出行为

MICROSTRUCTURE, MECHANICAL PROPERTIES AND INTERPHASE PRECIPITATION BEHAVIORS IN V-Ti MICROALLOYED STEEL

采用热模拟实验研究了等温温度对V-Ti微合金钢组织性能及相间析出行为的影响规律,利用OM和TEM分析了不同等温温度下实验钢的组织特征.结果表明,不同等温温度下均可得到大量铁素体组织,随等温温度的降低,铁素体体积分数增加,铁素体晶粒尺寸减小.不同等温温度下均可观察到平面相间析出,且降低等温温度可显著细化相间析出列间距和析出粒子尺寸.纳米碳化物具有NaCl型晶体结构,晶格常数约为0.436 nm,同铁素体基体满足(100)carbide//(100)ferrite和[011]carbide//[001]ferrite的B-N关系.在680℃下等温30 min,沉淀强化量可达到360.6 MPa.

The microstructure, mechanical properties and precipitation behaviors in a low carbon V-Ti micro- alloyed steel were investigated using thermal simulation. The microstructural characteristics of tested steel were an- alyzed using OM and TEM. The results show that the larger volume fraction of ferrite can be obtained for different isothermal temperatures. The ferrite volume fraction is increased and ferrite grain size is reduced as the isothermal temperature is lowered. The planar interphase precipitation can be observed for different isothermal temperatures, and both sheet spacing and precipitates size are refined by lowering isothermal temperature. Moreover, the nanome- ter-sized carbides have a NaCl-type crystal structure with a lattice parameter of about 0.436 um and they can obey one variant of Baker-Nutting （B-N） orientation relationship of （100）c//（100） and [011 ]/[001 ]. The pre- cipitation hardening for the specimen treated at 680 ℃ for 30 min can reach 360.6 MPa.