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采用手工电弧焊对D36级结构用钢进行焊接,分析预热保温工艺对焊接接头微观组织、硬度的影响,并通过电化学测试评价不同工艺焊缝金属在模拟海水中的腐蚀行为。结果表明:D36钢焊接热影响区铁素体和无碳贝氏体针状平行分布,焊缝区为柱状铁素体和粒状珠光体;经预热保温的焊缝晶粒细化、组织均匀,整体硬度大于210HV1.0,冲击韧性提高,裂纹倾向降低;焊缝经100℃预热+150℃保温后,焊缝腐蚀电流密度最低,为2.4μA/cm2,腐蚀电位接近母材,电荷传递电阻达3683Ω,膜层稳定性最佳,是最优的热处理工艺。
The effect of preheating and thermal insulation process on the microstructure and hardness of welded joints was analyzed by hand arc welding of D36 grade structural steel. The corrosion behavior of different weld metal in simulated seawater was evaluated by electrochemical tests. The results show that there are parallel distributions of ferrite and carbon-free bainite in the heat-affected zone of D36 steel, and the weld zone is columnar ferrite and granular pearlite. The preheated and heat-retained weld grain is refined and the microstructure is uniform , The overall hardness is greater than 210HV1.0, the impact toughness increases, the crack tendency decreases. The weld current after preheating at 100 ℃ and holding at 150 ℃ has the lowest corrosion current density of 2.4μA / cm2, the corrosion potential close to the base metal, the charge transfer Resistance of 3683Ω, the best film stability, is the best heat treatment process.