Chen Yujiong, Sun Hua, Li Zechen, Wu Yi, Xiao Yakai, Chen Zhe, Zhong Shengyi, Wang Haowei
State Key Laboratory of Metal Matrix Composites, Shanghai Jiao Tong University, Shanghai 200240, China.
SJTU-ParisTech Elite Institue of Technology, Shanghai Jiao Tong University, Shanghai 200240, China.
Materials (Basel). 2020 Jan 17;13(2):451. doi: 10.3390/ma13020451.
Selective laser melting (SLM) is known to generate large and anisotropic residual stresses in the samples. Accurate measurement of residual stresses on SLM-produced samples is essential for understanding the residual stress build-up mechanism during SLM, while a dramatic fluctuation can be observed in the residual stress values reported in the literature. On the basis of studying the influence of surface roughness on residual stress measured using X-ray diffraction (XRD), we propose a procedure coupling XRD technique with pretreatment consisting of mechanical polishing and chemical etching. The results highlight that residual stresses measured using XRD on as-built SLM-produced samples with high surface roughness are significantly lower than those measured on samples with finished surface, which is due to the stress relaxation on the spiked surface of as-built samples. Surface distribution of residual stresses and the effect of scanning strategy were systematically investigated for SLM-produced AlSi10Mg samples. Microstructural morphology was observed at the interface between sample and building platform and was linked to the surface distribution of residual stresses. This procedure can help us accurately measure the residual stresses in SLM-produced samples and thus better understand its build-up mechanism during the SLM process.
众所周知，选择性激光熔化（SLM）会在样品中产生较大的各向异性残余应力。准确测量SLM制备样品的残余应力对于理解SLM过程中的残余应力累积机制至关重要，然而文献报道的残余应力值却存在显著波动。在研究表面粗糙度对使用X射线衍射（XRD）测量残余应力的影响的基础上，我们提出了一种将XRD技术与由机械抛光和化学蚀刻组成的预处理相结合的方法。结果表明，使用XRD测量的具有高表面粗糙度的SLM制备的原始样品的残余应力明显低于在具有精加工表面的样品上测量的残余应力，这是由于原始样品尖峰表面上的应力松弛所致。系统地研究了SLM制备的AlSi10Mg样品残余应力的表面分布和扫描策略的影响。在样品与构建平台之间的界面处观察到微观结构形态，并将其与残余应力的表面分布联系起来。该方法可以帮助我们准确测量SLM制备样品中的残余应力，从而更好地理解其在SLM过程中的累积机制。
