表面喷丸强化处理对TC11钛合金疲劳性能的影响

目的改善TC11钛合金的抗疲劳性能。方法采用喷丸表面强化工艺对TC11钛合金进行了表面强化处理,研究了喷丸强化处理、喷丸+二次喷丸强化处理对TC11钛合金试样表面粗糙度、残余应力、显微组织及疲劳性能的影响。结果喷丸处理能够在试样表层引入厚度约230?m的残余压应力场,但同时导致试样表面粗糙度值增加。喷丸后进行表面二次喷丸,试样表面残余压应力值和残余压应力峰值提高,但残余压应力峰值的位置和残余压应力层的厚度变化不大。二次喷丸对试样表面起到一定程度的修复作用,使试样表面粗糙度值降低。喷丸后试样表层组织发生明显的塑性变形,晶粒变细,而喷丸+二次喷丸处理可使试样表层组织得到进一步细化。喷丸处理后,试样的疲劳强度由480 MPa提高至540 MPa,提高了12.5%,二次喷丸使试样的疲劳强度提高至570 MPa,在喷丸的基础上继续提高了5.5%。结论喷丸后对试样表面进行二次喷丸对表层残余应力场的影响不大,二次喷丸主要通过降低试样表面粗糙度值和细化试样表层组织,使试样的疲劳强度得到进一步提高。

Effects of Surface Shot Peening Strengthening on Fatigue Property of TC11 Titanium Alloy

The work aims to improve the fatigue resistance of titanium alloy.The surface strengthening process of shot peening was used for surface strengthening treatment ofTC11 titanium alloy.Effects of shot peening strengthening,shot peening+second shot peening strengthening on surface roughness,residual stress,rnicrostructure and fatigue resistance of TC11 titanium alloy sample were studied.The shot peening treatment could introduce nearly 230 μm thick compressive residual stress field to the sample surface,but meanwhile increase the roughness value of sample surface.After second shot peening,both the surface residual compressive stress and peak residual compressive stress increased,while the location of peak compressive residual stress and thickness of compressive residual stress layer showed little change.The second shot peening had certain repair effect on the sample surface and decrease surface roughness value of the samples.The surface tissue was subject to obvious plastic deformation after shot peening,and the grain size was refined.Compared with the samples after shot peening,shot peening+second shot peening could further refine the sample surface organization.After shot peening,fatigue strength of the samples increased from 480 MPa to 540 MPa by 12.5％;after the second shot peening,the fatigue strength of the samples increased from 540 MPa to 570 MPa by 5.5％.The second shot peening has little influence on residual stress field of the surface,it improves the fatigue strength of titanium alloy mainly by reducing the surface roughness value and refining surface organization of the samples.