2205双相不锈钢局部干法水下可调环形激光焊接组织性能研究

Microstructure and Properties of 2205 Duplex Stainless Steel Welded by Local Dry Underwater Laser with Adjustable Ring-Mode

摘要:

针对水下焊接凝固过程冷却速度快，焊缝组织性能恶化等问题，采用可调环形激光对2205双相不锈钢进行局部干法水下焊接试验，同时与陆上焊缝做对比，具体研究中心和环形激光不同比例对焊缝成形、微观组织及力学性能的影响。结果表明，熔深主要受中心激光的影响，且中心功率占比增大时，焊缝表面氧化程度变得严重，表面粗糙度增大。与陆上同参数的组织相比，水下焊缝的魏氏奥氏体含量增加，晶内奥氏体数量减少甚至消失。随着环形激光占比提高，焊缝中奥氏体 含量无明显变化，焊缝晶粒尺寸和纵横比降低，焊缝两侧柱状晶生长的方向性减弱，小角度晶界数量增多。在性能方面，水下接头的抗拉强度略高于陆上，但延伸率比陆上要低，而随着环形激光功率占比由1/3提高到2/3，水下接头延伸率提升 了约50%。

Abstract:

To address the issues of rapid cooling rate during the solidification in underwater welding and the deterioration of the microstructure and properties, this work conducted local dry underwater welding experiments on 2205 duplex stainless steel using adjustable ring-mode laser. Meanwhile, compared with in-air welds, the effects of the power ratio between center and ring lasers on weld formation, microstructure and mechanical properties were investigated. The results show that the center laser mainly affects the penetration depth. With the increase in proportion of central power, the oxidation degree and surface roughness of the weld become more severe. In terms of microstructure, the underwater weld exhibits an increase in Widmanst?tten austenite content, but a decrease in or even disappearance of intragranular austenite, compared to welds produced with the same parameters in air. With the increase in proportion of ring laser, the austenite content in the weld shows no significant change, the grain size and aspect ratio of the weld decrease, the directionality of columnar crystal growth on both sides of the weld weakens, and the number of low-angle grain boundary increases. In terms of performance, the underwater joints exhibit slightly higher tensile strength but lower elongation than those welds in air. As the proportion of ring laser power increases from 1/3 to 2/3, the elongation of underwater joints increases by about 50%.