奥氏体不锈钢焊接接头常见问题及分析

赵肖飞 车秀花

摘 要：奥氏体不锈钢，是指在常温下具有奥氏体组织的不锈钢。当钢中含铬18%左右、含镍8～10%时，便有稳定的奥氏体组织产生时，称为奥氏体不锈钢。奥氏体不锈钢无磁性、它不能通过热处理方法提高强度和硬度，如经淬火也不能硬化，而用加工硬化的方法可使奥氏体不锈钢强化。但它比其它不锈钢具有更优良的耐腐性、耐热性和塑性，可焊性良好，是不锈钢中得到最广泛应用的一种。奥氏体不锈钢与其他不锈钢相比较易焊接。但由于合金成分含量不同、金相组织转变及稳定化元素的变化，在将其进行实际应用的过程中，会受到多种因素的限制影响，焊件质量较差，对其使用寿命和质量造成不良影响。导致焊接缺陷问题的发生，焊接接头常出现以下问题，现总结如下：

关键词：奥氏体不锈钢; 焊接接头; 问题分析;

Abstract： austenitic stainless steel refers to stainless steel with austenitic structure at room temperature. When the steel contains about 18% chromium， nickel 8～10%， there is a stable austenitic structure， known as austenitic stainless steel. Austenitic stainless steel without magnetic， it can not improve the strength and hardness through heat treatment method， such as quenching can not harden， and with the method of processing hardening can make austenitic stainless steel strengthened. But it is better than other stainless steel corrosion resistance， heat resistance and plastic， good weldability， is the most widely used in stainless steel. Austenitic stainless steels are easier to weld than other stainless steels. However， due to the different content of alloy composition， the change of metallographic structure and the change of stabilizing elements， the alloy will be restricted by a variety of factors in the process of its practical application. As a result of the occurrence of welding defects， the welding joints often have the following problems， which are summarized as follows：

Key words： austenitic stainless steel; Welded joint; Problem analysis;

一、焊接接头常出现的问题及分析

1、热裂纹

热裂纹是奥氏体不锈钢焊接时比较容易产生的一种缺陷，包括爆缝的纵向和横向裂纹、火口裂纹、打底焊的根部裂纹和多层焊的层间裂纹等，特别是含镍量较高的奥氏体不锈钢。奥氏体不锈钢具有较高的热裂纹的热裂纹敏感性，尤其焊接过程中焊工操作不当，收弧时弧坑未填满、接头速度慢时最易造成弧焊裂纹。当弧坑裂纹混入焊缝焊缝中时往往会引起热裂纹的扩展。这是由于奥氏体不锈钢热导率小、线膨胀系数大，焊接时焊缝金属及近缝区在高温承受较高的拉伸应力和拉伸应变，加上一些杂质元素和合金元素在粗大的柱状晶间形成低熔点的液态膜，形成热裂纹。……