知识与财富的链接
目的 分析激光冲击与机械喷丸复合强化钛合金表层残余应力场及其在疲劳载荷下的稳定性。方法 采用薄壁叶片强化参数先后对TC17钛合金表面进行激光冲击强化和喷丸强化,利用X射线衍射法分析两种工艺复合强化表层的残余应力分布,并分别在25、400 ℃拉-拉疲劳加载条件下分析复合强化表层残余应力的稳定性。结果 激光冲击与喷丸复合强化表面残余应力值为-600 ~ -800 MPa,残余压应力幅值沿深度不断递减,压应力层深度为0.7~0.8 mm。表面至0.1 mm深度范围内的残余应力分布梯度较大,其分布特征主要受控于喷丸工艺,而距表面0.1 mm以下的残余应力分布梯度较小,其分布特征受控于激光冲击强化工艺。结论 激光冲击和喷丸强化顺序对最表层残余应力的均匀性有一定影响,对最表层以下的残余应力分布影响较小。复合强化表面残余应力在室温疲劳加载后具有较好的稳定性,在400 ℃疲劳加载下发生一定量松弛后趋于稳定。
The work aims to study the residual stress field of compound strengthening case produced by laser peening and shot peening on titanium alloy and its stability in the fatigue loading. TC17 titanium alloy was successively strengthened by laser peening and shot peening with the parameters of thin-wall blade and the distribution of residual stresses on compound strengthening surface was studied under X-ray diffraction method and its stability in tension-tension fatigue loads was analyzed at 25 ℃ and 400 ℃ respectively. The residual stress on compound strengthening surface by laser peening and shot peening fluctuated between -600 ~ -800 MPa and compressive residual stresses decreased gradually along with the depth. The depth of compressive residual stresses was 0.7~0.8 mm. The residual stresses in the depth from surface to 0.1 mm had larger distribution gradient and the distribution features were mainly dominated by shot peening. While, the residual stresses under 0.1 mm from the surface had smaller distribution gradient and the distribution features were mainly dominated by laser peening. The process sequence of laser peening and shot peening has certain influence on the uniformity of superficial residual stresses, but hardly af-fects the distribution of residual stresses in depth. The residual stresses of compound strengthening surface have excellent stability under fatigue load at room temperature, whereas it has amount of relaxation and tends to be stable under fatigue load at 400 ℃.
