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用Ⅱ型试样以慢拉伸方法研究了拉伸速度和极化电位对LC4铝合金应力腐蚀开裂行为的影响。采用应力腐蚀开裂面积A_(SCC)、应力腐蚀最大抗拉强度σ_(SCC)及其所对应的应变ε_(SCC)作为衡量应力腐蚀开裂敏感性的参数。结果表明,随拉伸速度降低,应力腐蚀开裂敏感性升高,但用σ_(SCC)来表现应力腐蚀开裂的敏感性不如A_(SCC)明显。阳极极化使抗拉强度下降;阴极极化时。若极化电位较小,则抗拉强度略有升高,强阴极极化抗拉强度则又会降低,说明应力腐蚀包含氢脆和阳极溶解两种机制。断口形貌观察发现,开路、阴极极化和充氢时的断口形貌相同,阳极极化则与其不同,表明开路时的应力腐蚀开裂是以氢脆为主的。
The effect of tensile speed and polarization potential on the stress corrosion cracking behavior of LC4 aluminum alloy was investigated by slow drawing method with type Ⅱ specimen. The stress corrosion cracking area A SCC, the maximum stress corrosion cracking σ SCC and its corresponding strain SC SCC were used as parameters to measure the stress corrosion cracking susceptibility. The results show that with the decrease of tensile velocity, the sensitivity to stress corrosion cracking increases. However, the sensitivity of SCC to stress corrosion cracking is not as obvious as that of SCC. Anode polarization reduces tensile strength; cathodic polarization. If the polarization potential is small, the tensile strength slightly increased, and the strong cathodic polarization tensile strength will be reduced, indicating that stress corrosion includes hydrogen embrittlement and anodic dissolution of the two mechanisms. The observation of the fracture surface shows that the morphology of the fracture surface is the same with the open circuit, the cathode polarization and the hydrogen charging. The anodic polarization is different from that of the anodic polarization. It shows that the stress corrosion cracking in the open circuit is dominated by hydrogen embrittlement.