激光选区熔化Inconel 625合金开裂行为及抑制研究
发布时间：2018-08-25 19:53
【摘要】：裂纹是激光选区熔化(SLM,selective laser melting)镍基高温合金最严重的缺陷之一,严重削弱了材料的力学性能。采用逐行扫描策略制备了Inconel 625合金试样,利用扫描电子显微镜(SEM)、电子背散射衍射(EBSD)等检测方法研究了裂纹微观形貌、周边元素和晶粒分布等。SEM结果显示在常温下成形件内部形成大量细小裂纹,裂纹长度约100μm。裂纹形成的内因是在快速凝固的过程中,由于Nb,Mo元素的局部偏析,形成(γ+Laves)共晶凝固。同时在脆性相Laves周围形成应力集中,导致沿着晶界开裂,SLM高凝固速率产生的残余应力是微裂纹产生的直接原因。通过基板加热工艺减小热残余应力,利用X射线测定了不同预热温度(150和300℃)下的残余应力值。结果显示基板预热降低了热残余应力,并最终抑制了裂纹的产生,随着温度的升高,裂纹数量逐渐减少,在预热温度300℃时裂纹数量最少。
[Abstract]:Crack is one of the most serious defects in laser selective melting (SLM,selective laser melting) nickel base superalloy, which seriously weakens the mechanical properties of the material. The microstructure of Inconel 625 alloy was studied by scanning electron microscope (SEM), (SEM), electron backscattering diffraction (EBSD), etc. SEM results show that a large number of small cracks are formed in the forming parts at room temperature, and the crack length is about 100 渭 m. The internal cause of crack formation is the formation of (纬 Laves) eutectic solidification due to local segregation of Nb,Mo elements during rapid solidification. At the same time, stress concentration is formed around the brittle phase Laves, which leads to the crack along the grain boundary and the residual stress produced by the high solidification rate is the direct cause of the microcracks. The thermal residual stress was reduced by the substrate heating process. The residual stress values at different preheating temperatures (150 and 300 鈩，
本文编号：2203930
[Abstract]:Crack is one of the most serious defects in laser selective melting (SLM,selective laser melting) nickel base superalloy, which seriously weakens the mechanical properties of the material. The microstructure of Inconel 625 alloy was studied by scanning electron microscope (SEM), (SEM), electron backscattering diffraction (EBSD), etc. SEM results show that a large number of small cracks are formed in the forming parts at room temperature, and the crack length is about 100 渭 m. The internal cause of crack formation is the formation of (纬 Laves) eutectic solidification due to local segregation of Nb,Mo elements during rapid solidification. At the same time, stress concentration is formed around the brittle phase Laves, which leads to the crack along the grain boundary and the residual stress produced by the high solidification rate is the direct cause of the microcracks. The thermal residual stress was reduced by the substrate heating process. The residual stress values at different preheating temperatures (150 and 300 鈩，
本文编号：2203930
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