研究了黄铜在静态腐蚀表面疏松层的应力状态,通过测量自由端挠度的变化及用SEM技术测量脱Zn层的厚度,计算了在脱Zn层和基体界面处生产的拉应力,其稳定值约等于黄铜屈服强度的1/5,在SCC过程中这个附加的拉应力将协助外应力促进位错发射和运动,从而SCC裂纹形核。
The stress state in the dezinc layer for brass due to free corrosion was investi- gated. The top end of foil brass sample with one side protected, was fixed. The free end bent towards corrosion surface gradually during corrosion in 1 mol/L NH40H +5g/L CuC12 solution, when the dezinc layer was formed. The deflection of the free end was measured. The loose dezinc layer was studied by SEM, and its thickness was measured. The stress state at the interface of dezinc layer/substrate was calculated. The results showed that a ten- sile stress was developed at the alloy/dezinc layer interface, which was 23.4 MPa, about 1/ 5 of yield strength for brass. It is possible that this additional tensile stress will assist the applied stress to facilitate dislocation emission and motion, and enhance micro-crack nucle- ation for stress corrosion cracking.
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