Abstract: Based on the influence of each alloy elements on the properties, microstucture and the welding cold crack of materials, and combined with the existing equipment and process technology conditions, the chemical compositions of the 80 kg class high strength steel of non-preheat welding at low temperature are designed. It’s found that the Y-groove welding cracking test samples (welding crack) of developed steel plate with low temperature unpreheat welding are not welding crack after air cooling 48 hours. At the same time,the unpreheat welding experiments respectively used for CO₂ gas shielded welding and manual arc welding at 5 ℃ ,15 ℃ and room temperature with heat input 20 kJ/cm of test steel. Results show that tensile strength of welding joints of the 80 kg class high strength steel plates unpreheat welding at 5 ℃ , 15 ℃and room temperature is 832 ~857 MPa and weld seam impact energy at -20 ℃ is 55 ~ 127 J to meet the requirement of standard.

摘要： 根据各合金元素对材料性能、微观组织及焊接冷裂纹等的影响，结合现有设备和工艺技术条件,设计岀80 kg级低温不预热焊接高强钢的化学成分。用该开发钢板做低温不预热焊接Y-形坡口铁研(焊接裂纹)试验发现，空冷48 h后没有出现焊接开裂。同时，在5 ℃、15 ℃及常温下，热输入为20 kJ/cm时，釆用CO₂气体保护焊及手工电 弧焊对试验钢板分别进行了'不预热焊接试验，结果表明，该80 kg级髙强钢板在5℃，15℃及常温下不预热焊接接头 的抗拉强度832～857 MPa, -20 ℃焊缝冲击功55~127J,满足标准要求。

关键词: 不预热焊接, 80 kg高强钢, Y-形坡口铁研