锌冶炼冷凝器W管的失效分析与对策

针对某冶炼厂冷凝器W管寿命短且频繁发生爆裂的问题,探讨其失效原因,寻找提高寿命的方法.基于“导致裂缝损坏的最主要原因是液体金属脆化现象(LMF),而应力集中对LMF的存在和发展的影响极大”的观点,对W管进行了残余应力测量、热应力有限元以及材质和制造工艺的分析.研究结果表明:造成W管失效的根本原因是W管的材料耐腐蚀性较弱,高温腐蚀使W管厚度减小;而W管的弯曲外侧存在显著的残余应力,工作中又受显著的热应力作用,极易产生裂纹并迅速扩展,导致裂缝损坏而失效;此外,据此制定了提高W管寿命的措施.

The failure analysis and corresponding methods for W-shape pipe of the cooler in the melting process of zinc

The cooler is important equipment in the melting process of Zinc. In a melting factory it is a frequent problem that the W-shape pipe of the cooler breaks after working for a few days. This paper aims to find the failure reasons and propose the methods to improve the situation. On the basis of such a viewpoint that "liquid metal fragility (LMF) is the major cause of crack failure and stress concentration contributes much to the LMFs existence and development", the authors have done a lot of research work, including measuring the residual stress, calculating the thermal stress with finite element analysis software and analyzing the material and manufacturing process of W-shape pipe. The results show that the essential cause of failure lies in the material which can not endure the corroding of hot liquid Zinc, so the W-shape pipe becomes thinner and thinner. There is mass residual stress on the bent parts of W-shape pipe, at the same time thermal stress also has great effects on those parts in work, therefore cracks come into being easily and expand quickly, at last resulting in failure. In this paper a series of methods are proposed to improve the lifetime of the W-shape pipe.