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用测试~(64)Cu和~(65)Zn同位素γ射线的放射性示踪技术研究了在慢应变速率动态拉伸条件下70/30黄铜在室温1M NaNO_2溶液中,-0.1V(SCE)下的应力腐蚀开裂(SCC)和脱锌行为。结果说明,包含铜在内的局部阳极溶解是该体系SCC的根本原因,而大量的脱锌则加剧了开裂敏感性。在应力达到最高拉伸应力(σ_(UTS))之前的裂纹稳态扩展阶段,脱锌系数最大,此阶段之后由于铜的溶解比例增大,脱锌系数相对较低。在稳态扩展阶段,裂纹尖端导致最大脱锌系数的应变速率估计约为初始应变速率的4倍左右。按择优溶解的体扩散模型算得SCC过程中锌的扩散系数可达10~(-11)cm~2/s数量级以上。文中还讨论了黄铜在亚硝酸盐溶液中SCC过程的脱锌机理。
The radioactive tracing techniques of ~ (64) Cu and ~ (65) Zn isotope γ-rays were used to study the effect of -0.1V (SCE) on the stability of 70/30 brass in 1M NaNO_2 solution under dynamic strain of slow strain rate Under stress corrosion cracking (SCC) and dezincification behavior. The results indicate that local anodic dissolution, including copper, is the root cause of SCC in the system, while a large amount of dezincification aggravates the cracking susceptibility. The dezincification coefficient is the largest at the crack initiation stage before the stress reaches the maximum tensile stress (σ_ (UTS)). After this stage, the dezincification coefficient is relatively low due to the increase of copper dissolution ratio. In the steady-state expansion phase, the strain rate at the crack tip leading to the maximum dezincification coefficient is estimated to be about 4 times the initial strain rate. The diffusion coefficient of zinc in SCC can be calculated to be in the order of 10 ~ (-11) cm ~ 2 / s according to the bulk diffusion model. The article also discusses the dezincification mechanism of brass in nitrite solution SCC process.