热等静压处理对SLM成形AlSi10Mg疲劳性能影响

Influence of Hot Isostatic Pressing on the Fatigue Properties of AlSi10Mg Fabricated by Selective Laser Melting

针对激光选区熔化(selective laser melting,SLM)成形AlSi10Mg合金疲劳寿命分散、疲劳性能存在显著各向异性等问题,对比分析了SLM成形态及HIP处理态试样的S-N曲线及微观组织差异性。结果分析表明,由于成形方向造成SLM成形件内部缺陷分布呈现一定方向性,在相同应力水平下,SLM成形AlSi10Mg在X(Y)方向的疲劳寿命优于Z向;相同寿命条件下,X(Y)取样方向的疲劳强度比Z取样方向的疲劳强度高28%~49%。在490℃热等静压处理后,X(Y)、Z两个方向的疲劳寿命差异较SLM态明显减小。同时由于热等静压过程中,SLM沉积态组织中网状分布的枝晶发生了组织粗化和Si相粗化,导致HIP处理后疲劳强度尤其是在高应力水平下出现下降。

This study addresses the issue of dispersed fatigue outcomes and anisotropic behavior in fatigue specimens produced by selective laser melting(SLM).The fatigue life(S-N)curves and microstructures of AlSi10Mg alloy,fabricated via SLM and subsequently subjected to Hot Isostatic Pressing(HIP)treatment,were compared and analyzed.The results showed that the fatigue life in X(Y)direction of AlSi10Mg is better than that in Zdirection,because of the difference in the distribution direction of defects,attributed to the directional distribution of defects influenced by the SLM forming process.The fatigue strength in the X(Y)direction is 28%to 49%greater than in the Zdirection under equivalent fatigue life conditions.After hot isostatic pressing treatment at 490℃,the difference of fatigue life in two directions is obviously decreased compared to the SLM specimens,which was due to the large size defects was closed after hot isostatic pressing treatment.Moreover,the microstructure coarsening and Si phase coarsening during hot isostatic pressing process led to the decrease of fatigue strength,especially for fatigue tests at high stress level.