旋片喷丸对7B04-T6铝合金应力腐蚀抗性的影响

Effect of flap peening on stress corrosion cracking resistance of 7B04-T6 alloy

为研究喷丸对7B04-T6铝合金应力腐蚀抗性和静态力学性能的影响,采用旋片喷丸技术对7B04-T6铝合金进行0.1~0.2 A、0.2~0.3 A两种喷丸强度的表面强化处理,进行喷丸前后试样表面粗糙度和残余应力的测定与分析、表面形貌观察、恒载荷应力腐蚀测试、材料静态强度对比测试,并用扫描电子显微镜对断口进行观察分析。结果表明:0.1~0.2 A和0.2~0.3 A两种喷丸强度可分别在7B04-T6铝合金表面形成-350 MPa和-275 MPa残余压应力;表面粗糙度Ra从喷丸前的0.9μm分别增大至1.6μm和1.8μm;在3%NaCl+0.5%H2O2(质量分数)溶液中、(35±1)℃、350 MPa恒载荷作用下应力腐蚀持续时间分别较未喷丸试样提高11.3倍和8.7倍,0.1~0.2 A喷丸强度改善效果更佳;喷丸处理不改变材料的强度极限和断面收缩率,两种喷丸工艺对静态强度和断面收缩率的影响一致。

The flap peening method with two different shot peening intensities were used to strength the 7B04-T6 for studying the effect of shot peeing on the stress corrosion cracking resistance and mechanical properties of 7B04-T6.Comparative testing about surface roughness,surface residual stress,surface topography,constant load stress corrosion cracking experiment and static strength tensile experiment were performed,the fracture surfaces were observed with SEM.The results show that,shot peening has imparted a surface residual compressive stress of−350 MPa(0.1-0.2 A intensity)and−275 MPa(0.2-0.3 A intensity).The surface roughness has increased from Ra 0.9μm to Ra 1.6μm(0.1-0.2 A intensity)and Ra 1.8μm(0.2-0.3 A intensity).The duration of stress corrosion cracking has extended with 11.3 times(0.1-0.2 A intensity)and 8.7 times(0.2-0.3 A intensity)in the 3%NaCl+0.5%H2O2 solution and with an application of 350 MPa load.Shot peening has not influenced the ultimate strength and percentage reduction in area,but slightly decreased the yield strength with a value of 15 MPa.