【摘要】 为探明1 000 MPa级高强钢焊接试板焊缝中UT、RT检测合格，而TOFD检测出的小尺寸当量密集性超标缺陷的成因，采用宏、微观金相分析，缺陷形貌表征等手段，对典型焊接缺陷的性质、分布规律以及产生要因进行了研究。结果表明，多发的TOFD检测小尺寸当量密集性超标焊接缺陷为氢致气孔类缺陷、夹渣类缺陷与再热裂纹类线性缺陷。其成因与熔池逸出条件、层/道间温度及焊接线能量控制、脱氢程度（冶金反应）有关。通过采用直流脉冲MAG焊方法增强熔池流动性，以及提高焊接保护气中CO₂比例促进冶金反应等工艺改进措施的制定，有效的消除了焊缝中密集微小气孔与夹渣缺陷的产生；通过对层/道间温度及焊接线能量的控制，有效的消除了焊道重热区再热裂纹的产生。对提高1 000 MPa级高强钢焊接接头性能和构件服役可靠性具有重要意义。更多还原

【Abstract】 To explore UT and The causes of the small size equivalent density exceeding the standard detected by TOFD were studied using macroscopic and microscopic metallographic analysis, defect morphology characterization, and other methods to investigate the properties, distribution patterns, and causes of typical welding defects that passed the RT test. The results indicate that the frequent TOFD detection of small-sized equivalent density exceeding welding defects includes hydrogen induced porosity defects, slag inclusion defects, and linear defects such as reheat cracks. Its formation is related to the conditions of molten pool escape, interlayer/inter pass temperature and welding line energy control, and the degree of dehydrogenation（metallurgical reaction）. By adopting the DC pulse MAG welding method to enhance the fluidity of the molten pool and increasing the proportion of CO₂ in the welding protective gas to promote metallurgical reactions, the development of process improvement measures has effectively eliminated the generation of dense micro pores and slag inclusions in the weld seam; By controlling the interlayer/pass temperature and welding line energy, the generation of reheat cracks in the weld seam has been effectively eliminated. It is of great significance to improve the performance of 1 000 MPa high-strength steel welded joints and the service reliability of components.更多还原