论文部分内容阅读
观察分析了机壳腐蚀裂纹的宏观特征及微观形貌,测定了裂纹扩展路径上腐蚀产物的成分。结果表明,机壳腐蚀裂纹是氯离子促进的应力腐蚀开裂。靠近熔合线附近的机壳本体组织较焊接前发生了明显变化,铁素体增多而奥氏体减少,且Cr2N析出。焊接导致机壳耐蚀性下降是引发其应力腐蚀开裂的一个重要原因。建议优化焊接工艺提高机壳的耐蚀性,或者对机壳进行焊后固溶处理以恢复其双相不锈钢的高耐蚀性。
The macroscopic and microscopic appearance of the corrosion crack of the shell was observed and analyzed, and the composition of the corrosion products on the crack propagation path was measured. The results show that the shell corrosion cracking is chloride-promoted stress corrosion cracking. The texture of the shell body near the fusion line changed significantly compared with that before welding. The ferrite increased and the austenite decreased, and Cr2N precipitated. Welding leads to corrosion resistance of the chassis is caused by stress corrosion cracking is an important reason. It is advisable to optimize the welding process to increase the corrosion resistance of the case or to post-weld the case to a solution treatment to restore the high corrosion resistance of its duplex stainless steel.