用十字型缺口试样和WOL缺口试样分别在压应力和拉应力下研究了黄铜在氨水中的应力腐蚀。实验表明,无论那种试样,在压应力下均能产生应力腐蚀。拉、压应力腐蚀门槛值之比K_(SCC)(压)/K_(SCC)(拉)分别等于5.9(WOL试样)和5.5(十字型试洋)。拉应力腐蚀是穿晶断裂。压应力腐蚀断口和K_1有关,当K_1较低时是典型的沿晶断口,而当K_1较高时则是混合断口。电镜观察表明,双向压应力下位错塞积在晶界和孪晶界;在双向拉应力下则晶内位错密度高于晶界,且晶界位错不呈塞积群。
Stress Corrosion Cracking (SCC)of H62 brass in 1N NH_4OH+5g/L CuCl_2 solution under compressive stress was investigated using notched cross specimen and medifide WOL notched sample. The results showed that SCC could occur if an applide compressive load was larger than a critical value. The threshold stress intensity nucleating SCC from the notch under compressive stress was 20.7 MPam~(1/2), but the corresponding value under tensile stress was 3.5 MPam~(1/2). The fracture surfaces of SCC under compressive stress were quite different from those under tensile stress. The latter was composed of cleavage and quasi-cleavage, but the former was intergranular characterized by parallel striation pattern when K_1<15.3 MPam~(1/2) and mixed fracture when K_1>15.3 MPam~(1/2)(cross specimen). The dislocation structure under compressive stress was also different from that under tensile stress.
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