B对发动机用真空感应熔炼GH600合金凝固组织和力学性能的影响

Impact of B-Doping on Microstructures and Reinforcement of Solidified GH600 Alloy Melted by Vacuum Induction

通过在发动机用真空感应熔炼GH600合金中加入不同添加量B元素的方式来提高合金的性能,实验测试研究B对其凝固组织和力学性能的影响。研究结果表明:当B添加量增大后,γ析出相组织形成更大的尺寸,并且析出量也明显增加,形成了更多的γ析出量,表现为线性变化。在B添加量低于0.05%下,合金晶界部位形成了许多颗粒状的硼化物;随着B添加量增大至0.080%,晶界处开始析出细小短棒形硼化物,同时在γ析出相区域析出了析出相态组织。在B加入量小于0.05%的时候,随着B加入量的提高,试样拉伸塑性呈现快速增大的趋势,试样断口区域形成了沿晶开裂的现象。当B添加量大于0.05%之后,随着B添加量增加,试样拉伸塑性发生了迅速下降,裂纹更易在析出相前沿出现萌生与扩展。

GH600-alloy,an advanced aero-engine material,was reinforced by B-doping in vacuum induction melting and by solidification.The influence of the B-content on the microstructures,phases and mechanical properties of the B-doped GH600-alloy was investigated with scanning electron microscopy and tensile strength measurement.The results show that depending on B-content,B-doping had a major impact.To be specific,as the B-content increased from 0.02%(wt)to 0.082%,the size and density ofγ-precipitation-phase cluster significantly increased,the borides granular-grains were gradually replaced by borides nano-rods at grai6 n boundaries;the tensile plasticity changed in a rapid increase-decrease manner,peaking at 0.05%.In tensile measurement of the sample with a B-content above 0.05%,cleavage easily formed,particularly at the precipitate-phase boundary,propagated and finally,resulted in cracks and/or fractures because of the rapidly decreased tensile plasticity,and that accounts for the fracture mechanism.