内燃机用激光增材制造Ti600合金原位拉伸组织演变分析

为了提高内燃机用激光增材制造Ti600合金的综合性能,对其进行原位拉伸力学测试,对微裂纹生成、扩展与断裂进行更加精确地观察,并分析不同原位拉伸位移下的微观组织及裂纹演变机制。研究结果表明:激光增材制造Ti600合金形成了具有粗大尺寸的柱状β晶,其生长方向与构造堆积方向一致;β晶界呈现出垂直生长的状态,在靠近β晶的区域形成了大量的板条型α晶以及生长方向一致的α簇组织;当原位拉伸位移增加后,裂纹沿着β晶界向上延伸,形成了偏向β晶界的裂纹;当位移量提高后,合金中形成了随机排列的晶粒,同时滑移方向也存在明显差异,导致交叉滑移带的形成。该研究对优化工艺方法及提升激光增材制造Ti600合金性能具有一定的参考价值。

Evolution analysis on in-situ tensile microstructure of Ti600 alloy manufactured by laser additive for internal combustion engine

In order to improve the comprehensive performance of Ti600 alloy manufactured by laser additive for internal combustion engine,the in-situ tensile mechanics test was conducted,and the generation,propagation and fracture of microcracks were observed more accurately to analyze the microstructure and the crack evolution mechanism under different in-situ tensile displacements. The results show that the columnar β crystals with coarse size are formed in Ti600 alloy manufactured by laser additive,and the growth direction is consistent with the structure accumulation direction. Furthermore,the β grain boundaries present a state of vertical growth,and a large number of lath-type αcrystals and α-cluster structures with the same growth direction are formed in the region near β crystals. When the in-situ tensile displacement increases,the crack extends upward along β grain boundaries to form the crack inclining to β grain boundaries. The randomly arranged grains are formed in the alloy,and the slip direction is obviously different to lead to the formation of cross slip zone when the displacement increases. Thus,the above research provides a certain reference value for optimizing the process method and improving the properties of Ti600 alloy manufactured by laser additive.