Delta ferrite in weld metal for duplex stainless steel

SUN Xian

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Delta ferrite in weld metal for duplex stainless steel
Vol. 49, Issue 8, Pages: 14-22(2019)
Published：2019
DOI：
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DOI：

SUN Xian. Delta ferrite in weld metal for duplex stainless steel[J]. Eletric Welding Machine2019, 49(8): 14-22. DOI：

摘要

探讨了双相不锈钢焊缝中δ-铁素体形成条件、对焊缝性能的影响及控制机理。结果表明

双相不锈钢焊缝组织是在铁素体基体晶界和晶内分布不同形态奥氏体的双相组织。在δ铁素体影响因素中

起决定作用的是焊缝的化学成分和冷却速度。焊缝中δ铁素体数量过高

对焊接接头抗腐蚀性和抗裂性产生不利影响。工程上所用焊缝中奥氏体与铁素体的最佳相比例应通过工艺评定来确定。优化焊缝化学成分是控制焊缝奥氏体形成的必要条件

而合理的工艺方法和焊接参数则是控制奥氏体形成的充分条件。

Abstract

The formation conditions

the influence on weld properties and the control mechanism of delta ferrite in duplex stainless steel weld are discussed. The results show that the weld structure of duplex stainless steel is a duplex structure of austenite with different morphologies distributed at grain boundaries and in grains of ferrite matrix. Among the influence factors of delta ferrite

the chemical composition and cooling rate of weld metal play a decisive role. Excessive amount of delta ferrite in the weld has an adverse effect on the corrosion resistance and crack resistance of the welded joint. The optimum ratio of austenite to ferrite in weld used in engineering should be determined by procedure qualification method. Optimizing the chemical composition of the weld is the necessary condition to control the austenite formation in the weld

while the reasonable process methods and welding parameters are the sufficient conditions to control the austenite formation.