喷丸强度对TA15钛合金型材表面完整性影响的数值和实验研究

Numerical and Experimental Investigations on the Effect of Shot Peening Intensity on the Surface Integrity of TA15 Titanium Alloy Profiles

摘要:

利用有限元模拟和喷丸实验研究了喷丸强度对TA15钛合金热挤压型材表面完整性的影响规律。对比了由数值模拟和喷丸实验得到的表面粗糙度和残余应力分布结果，验证了所建立的喷丸有限元模型的可靠性；研究了喷丸强度对材料表层显微硬度和微观组织的影响。实验结果表明，喷丸处理在TA15钛合金型材表层产生了最大数值为558~764 MPa且深度为115~151 μm的残余压应力层，材料表层发生塑性变形，位错密度增大，晶粒细化，表层硬度提高，形成了深度为100~150 μm的硬化层，同时表面粗糙度增大。最大残余压应力、压应力层深度和表层硬度随喷丸强度的增大而增大，但强度超过0.188 mmA后增加不明显，材料表面出现裂纹，且在0.222 mmA强度下，材料表面因折叠缺陷而发生残余应力松弛，降低了材料表面完整性。

Abstract:

The effect of the shot peening intensity on the surface integrity of TA15 titanium alloy hot extruded profile was numerically and experimentally studied. The surface roughness and residual stress distribution obtained by the numerical simulation were compared with the shot peening experimental results, and the reliability of the established finite element model was verified. The effects of shot peening intensity on the microhardness and microstructure of the material surface were investigated. The experimental results show that the compressive residual stress layer with a maximum value of 558~764 MPa and a depth of 115~151 μm was introduced into the surface of TA15 titanium alloy profile after shot peening. The plastic deformation occurs on the material surface, the grain is refined, the dislocation density and the hardness of the material surface increase. The hardened layer with a depth of 100~150 μm forms, and the surface roughness increases. The increase of the shot peening intensity increases the maximum compressive residual stress, the depth of the compressive residual stress layer and the surface hardness. However, the increase is not obvious when the intensity exceeds 0.188 mmA, and the cracks might appear on the material surface. Moreover, at the intensity of 0.222 mmA, the residual stress relaxation occurs on the material surface due to the folding defect, which reduces the surface integrity of the material.