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低碳钢的碱脆是低碳钢在碱性介质中应力腐蚀开裂(SCC)的一种形式。是碱液蒸发器破坏的主要原因。本文讨论了低碳钢在NaOH溶液中的阳极化行为、碱脆临界电位、焊缝和热处理条件对碱脆的影响,并对碱脆设备进行了金相剖析。认为低碳钢在NaOH溶液中的碱脆是属于应变诱发的、阳极溶解型的SCC。它在临界电位下发生,表面复盖有Fe_3O_4膜,塑性应变造成的膜破裂构成了活化-钝化电池,活化-钝化电池的电动势是碱脆的电化学推动力,而Fe_3C的优先溶解是碱脆的金属学原因。碱脆裂纹沿晶界扩展。
Alkali embrittlement of low carbon steel is a form of SCC for mild steel in alkaline media. Lye evaporator is the main reason for the destruction. In this paper, the anodizing behavior of mild steel in NaOH solution, the critical potential of alkali, the influence of welding seam and heat treatment conditions on the alkaline brittleness were discussed. It is considered that the alkali brittleness of mild steel in NaOH solution belongs to strain-induced, anodic dissolution type SCC. It occurs at the critical potential, the surface covered with Fe_3O_4 membrane, plastic strain caused by rupture of the membrane constitutes an activation - passivation of the battery, activation - passivation of the battery electromotive force is alkali-brittle electrochemical impetus, and the preferential dissolution of Fe_3C is Alkali brittle metal cause. Alkali-brittle cracks extend along grain boundaries.