Competitive failure analysis on tensile fracture of laser-deposited material for martensitic stainless steel-猫眼课题宝

马氏体不锈钢激光沉积材料拉伸断裂竞争失效分析

DOI：

10.1016/j.matdes.2017.01.014

发表时间：

2017-03

期刊：

Materials and Design

影响因子：

8.4

通讯作者：

中科院分区：

材料科学1区

文献类型：

作者：

Shaopeng Wei;Gang Wang;Jianchao Yu;Yiming Rong

在再制造应用中，需要沉积材料具有足够的机械性能，以保证修复零件的功能性和可靠性。从显微组织和力学性能的演变入手，对激光沉积FV 520 B马氏体不锈钢的拉伸断裂行为进行了全面的研究。样品采用激光热丝沉积法制备。采用专门设计的单轴拉伸试验方法对沉积样品的断裂行为进行了表征，并对晶粒尺寸、显微硬度分布、残余应力和析出物分布进行了研究。结果表明，拉伸断裂发生在多层激光加热引起的显微硬度波动较大的部位。熔敷材料的拉伸断裂模式有三种：界面断裂、热影响区断裂和热影响区/界面混合断裂。这是由于热影响区的微孔聚并和熔覆层/热影响区界面的界面开裂之间的竞争失效造成的。热影响区析出相的溶解和晶粒细化导致强度降低，韧性提高。

Sufficient mechanical properties of deposited materials are needed in remanufacturing applications to guarantee the functionality and reliability of repaired parts. The present paper described the tensile fracture behavior of laser-deposited FV520B martensitic stainless steel comprehensively based on evolution of the microstructure and mechanical property. The samples were fabricated by laser hot-wire deposition. The fracture behavior of the deposited samples was characterized using a specially designed uniaxial tension testing approach and investigated on the grain size, microhardness profile, residual stresses and precipitate distribution. The results show that the tensile fracture occurred at the position with high fluctuating microhardness caused by the multi-layer laser heating. Three tensile fracture patterns of deposited material were found: interfacial fracture, heat affected zone (HAZ) fracture and HAZ/interface hybrid fracture. They result from the competitive failure between microvoid coalescence in the heat affected zone and interfacial cracking in the clad layer/HAZ interface. Grain refinement and dissolution of precipitates occurred in heat affected zone, leading to a decrease of strength and increase of toughness.