用同一炉钢的铸件和锻件对比研究了在水介质中的应力腐蚀性能。结果表明:铸钢和锻钢应力腐蚀裂纹扩展的激活能相同,均为Q=5540cal/mol,且和氢渗透测出的表观扩散激活能一致。无论是阳极极化还是阴极极化,均使铸钢和锻钢的da/dt升高,但阴极极化较为明显。氢渗透测量表明:不论阳极极化或阴极极化,随着电流增大,饱和氢渗透量明显增加,极化对da/dt和氢渗透通量的影响相似。 试验温度对K_(ISCC)的影响极小,但铸钢的K_(ISCC)明显地比锻钢高。氢渗透测试结果发现锻钢的饱和氢渗透通量约比铸钢大一倍。这与断口观察一致,由此可以解释K_(ISCC)的差异。尽管断口形貌明显依赖开裂时的K_I值,但在K_(ISCC)附近锻钢全是沿品断口,而铸钢则以准解理为主。
The stress corrosion behaviour in water of the cast steel in contrast with the forged steel of same heat has been examined comparatively. It was shown that the activation energy of crack growth under stress corrosion of both cast and forged steels is identical, i.e. Q= 5540 cal/mol, and is in agreement with the apparent diffusion activation energy of H_2 permeation in steel. The da/dt for cast or forged steel increases no matter whether cathodic or anodic polarization, but the former influences predominantly. Correspondingly, the steady-state H_2 permeation flux increases steeply with the increase of polarizing current either cathodic or anodic polarization. The influences of polarization upon da/dt and H_2 permeation flux are similar, The testing temperature is found in a less effect on K_(ISCC). The K_(ISCC) of the cast steel determined is larger than that of the forged steel. It may be due to that the steady-state permeation flux for the forged steel is twice as many as that of the cast steel. For both cast and forged steels, the fracture modes are clearly dependent upon K_1 at the crack tip and a transition from dimple to quasi-cleavage or intergranular is observed on the fracture surfaces with decreasing K_1.
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