DH36海洋平台钢水下局部干法多层多道焊接工艺研究

Study on the Technology of DH36 Underwater Local Dry Multi-pass Welding

采用自行研制的水下焊接压力舱试验系统,模拟研究了不同水深下的环境压力对DH36海洋工程用钢的局部干法水下多层多道焊接工艺和质量的影响,根据AWS D3.6M—2010标准进行了焊接工艺评定。结果表明,60m以浅水深下,局部干法焊接接头的宏观检测、力学性能指标均满足B级接头质量要求,而且水深对于力学性能基本没有影响,但接头最高硬度会随着水深增加而略有提高。金相显微分析得知热影响区粗晶区组织为粒状贝氏体和少量板条马氏体,焊缝柱状晶区组织为沿晶界析出的先共析铁素体和大量的针状铁素体。

Self-designed underwater welding pressure chamber testing system is utilized to simulate the effect of environment pressure in various depth of water on the DH36 steel used in the oceanographic engineering by means of underwater local dry multi-pass welding procedure.The procedure qualification is conducted according to the standard of AWS D3.6M—2010.Experimental results show that the macroscopic examination and mechanical performance indexes of local dry welding joint satisfy with performance requirements of grade B.And the depth of water has no effects on mechanical performances while the maximum hardness would increase slightly along with the deeper depth.Metallographic analysis reveals that the coarse-grained heat-affected zone is filled with granular bainites and few lath bainites while the crystallizing morphologies on the weld seam are proeutectoid ferrites along with grain boundaries and large amount of acicular ferrites.