摘要
本文对激光重熔20CrMnTi材料表明改性层显微组织分布特征、表面硬度分布规律以及残余应力状态作了研究,结果表明,表面改性层由熔融层、相变硬化层及过渡层组成,且材料表面显微硬度得到大幅度提高,表面硬度达到HV841,约提高4倍。硬化层深度约1mm。残余应力测试得出最大残余应力出现在熔凝带中心,表现为压应力。随着离中心距离的增大,残余应力逐步降低,到熔化带边缘,表现为低幅值压应力;而熔池的外边缘应力在热影响区则转变为拉应力状态。
The microstructure distribution, surface hardness and residual stress of the 40Cr, which is modified by single - line solidification and folded - line solidification, are studied in this article. It is indicated that the surface micro-structure of the material treated by single - line laser solidification, is comprised of surface melting zone, sub - surface phase hardened zone and high temperature annealed zone connected with substrate. The difference between the folded - line laser solidification and the single - line solidification are the surface hardness and microstructure of the annealing region and secondary - hardened region. And the test of residual stress indicates that: in single - line laser rapid solidification, the maximal residual stress, which is pulling stress, emerges on the central line of the solidification zone. On the margin of melting zone, there exists compressive stress and in the heat affected zone there is pulling stress again. The residual stress of the folded - line solidification has new characteristics, that is the range values are smaller than those of single - line solidification, and the later solidification zones bring stress on the former solidification zones and furthermore tempered the former ones.
出处
《应用激光》
CSCD
北大核心
2002年第4期401-404,共4页
Applied Laser
