磨削表面粗糙度对γ-TiAl合金抗弯强度的影响

2020-02-18

作者：张欢欢，汪振华，刘耀文，章波单位：南京理工大学

摘要：为了研究表面加工质量对硬脆性高温合金抗弯性能的影响，对不同磨削表面粗糙度的全片层γ-TiAl（Ti-47.5Al-2.5V-1.0Cr）合金进行了抗弯性能试验，分析了表面粗糙度对其抗弯强度的影响规律。试验结果表明，随着表面粗糙度的增大，全片层γTiAl合金的抗弯强度明显降低。结合断裂形貌图分析了全片层γ-TiAl合金组织中裂纹的萌生、扩展及最终发生宏观断裂的方式，全片层γ-TiAl合金裂纹大多起裂于因加工纹理引起的应力集中区域附近的片层间，并优先在层间扩展，最终的断裂形式多为穿层的脆性瞬断。

关键词：γ-TiAl合金；表面粗糙度；抗弯强度；裂纹；全片层

中图分类号：TG111.91；TH161.1文献标志码：ADOI：10.3969/j.issn.1000-7008.2020.01.010

Flexural Strength of γTiAl Alloy Based on Grinding Surface Roughness

Zhang Huanhuan，Wang Zhenhua，Liu Yaowen，Zhang Bo

Abstract:In order to study the effect of surface processing quality on the bending properties of hardbrittle super alloys，the flexural performance test of γTiAl alloy(Ti47.5Al2.5V1.0Cr) is carried out with different grinding surface roughness，and the influence of surface roughness on the flexural strength is analyzed.The results show that the flexural strength of the alloy decreased with the increase of surface roughness.The measure of crack′s initiation and propagation and it′s fracture form combining with the fractography of fully lamellar γTiAl alloy are analyzed.The crack of fully lamellar γTiAl alloy generated on the interlayer and the boundary of layer group near the stress concentration are caused by processing，and have priority in the interlayer expansion，the final form of fracture is mostly brittle transient.

Keywords:γTiAl alloy；surface roughness；flexural strength；crack；fully lamellar