固定式排水罩水下局部干法CO2气体保护焊焊接工艺优化及接头性能分析

文中在常压下利用高速摄像分析了药芯焊丝焊接的熔滴过渡特点，在压力舱内进行了DH36钢的局部干法焊接工艺参数的优化研究.在此基础上，补偿了次级电缆的压降，最终确定的海下焊接试验的参数为焊接电流175~180 A，焊机的输出电压32~34 V.利用该焊接工艺参数和自行开发研制的固定式小型排水罩，在渤海海域23 m水深进行了焊接试验，并根据AWS D3.6M:2010标准对接头进行测试分析.结果表明，焊缝内无气孔、夹渣和裂纹等缺陷，焊缝组织主要是由针状铁素体、侧板条铁素体和多边形铁素体组成，各项指标均达到AWS D3.6M:2010标准规定的A级接头要求，证明了开发的基于固定式排水罩的水下局部干法CO₂焊接技术可以应用在DH36钢海洋导管架结构的修复.

Optimization of underwater welding process in stationary local dry cavity and analysis of welding joint properties

The droplet transfer of flux cored arc welding at normal pressure was investigated with high-speed digital camera system. Based on the experiments under 0.2 MPa pressure in hyperbaric chamber, the welding parameters were optimized. The voltage decrease of cable was compensated. The final current and voltage setting values of the welding machine used for the practical test in Bohai Sea were 175~185 A and 32~34 V, respectively. The test in stationary local dry cavity was carried out at the water depth of 23 m in Bohai Sea. According to AWS D3.6M:2010, the mechanical properties tests were taken. Results indicated that no pores, inclusions and cracks were founded in the welding joints. The microstructures of the weld metals were mainly consisted of acicular-ferrite, ferrite-side-plate and polygonal-ferrite. All the tested mechanical properties reached the requirements of Class A Weld according to the standard. The experimental results indicated that local dry underwater welding based on the stationary drainage cavity can be applied in the repair of DH36 offshore jacket structures.