含钛微合金钢的高温热塑性及断裂机理

运用Gleeble 1500热模拟机对600~1350益温度范围内SS400B钢加入钛后的高温力学性能进行测试，对断口形貌及低倍组织进行扫描电镜观察，研究其断裂机理及影响因素。利用热力学软件Factsage对不同钛含量条件下第二相粒子的析出情况进行计算分析。结果表明，在实验温度范围内测试试样的断面收缩率均超过了45%；在高温区生成的铝钛氧化物可作为塑坑的形核核心，促进延性断裂的发生；同时由于铝钛氧化物、氮化钛的生成，降低了对钢塑性有害的氮化铝生成；沿晶铁素体和沿晶渗碳体的生成恶化钢的塑性，促进沿晶脆性断裂的发生。

Hot ductility and fracture mechanism of a Ti-bearing microalloyed steel

The hot ductility of a Ti-bearing microalloyed steel was studied at temperatures of 600 to 1350℃ by a thermal simulator Gleeble 1500. The fracture morphology and microstructure were observed by scanning electron microscopy and optical microscopy. The precipitate behavior of second phase particles was calculated by the thermodynamic software Factsage. The hot ductility curve shows that SS400B steel with additional titanium has very good hot ductility during all the tested temperature range, and all the values of reduction in area are larger than 45%. Alx Tiy Oz generation at high temperature can act as nucleation sites for dimples to promote the ductile fracture. The amount of detrimental AlN can be reduced due to the formation of Alx Tiy Oz and TiN. Intergranular ferrite and cementite promote the intergranular brittle fracture.