通过经验公式和斜Y型坡口焊接裂纹试验研究了50 mm厚EH36-Z35海洋工程用钢在低温环境中的焊接冷裂纹敏感性。结果表明：由经验公式计算得出试验钢具有一定的焊接冷裂纹敏感性，且焊前预热温度在114 ℃时才能保证结构的安全性；由斜Y型坡口焊接裂纹试验得到15 ℃环境中焊前预热温度应高于125 ℃，5 ℃环境中焊前预热温度应高于150 ℃，试验结果与经验公式计算值接近；在-18~15 ℃低温环境中，预热温度相同与绝对湿度相近条件下，随着环境温度的降低，试验钢焊缝根部裂纹率增加，热影响区最高硬度升高；计算得到-18~15 ℃环境中试验钢的最大临界拘束应力为577 MPa，而由斜Y型坡口焊接裂纹试验引入的拘束应力为588~1 695 MPa，满足裂纹形成条件，导致裂纹产生并扩展。

The welding cold crack sensitivity of 50 mm thick EH36-Z35 marine engineering steel in a low temperature environment was studied by empirical formula and inclined Y-groove welding crack tests. The results show that the test steel had a certain welding cold crack sensitivity, and the safety of the structure could be guaranteed only when the preheating temperature before welding was about 114 ℃, according to the calculation by the empirical formula. The preheating temperature before welding should be higher than 125 ℃ at environmental temperature of 15 ℃ and should be higher than 150 ℃ at environmental temperature of 5 ℃, according to the inclined Y-groove welding crack tests. The test results were close to the theoretical calculated values. At environmental temperatures of -18 ℃ to 15 ℃ and with similar absolute humidity and same preheating temperature, the crack rate at the weld root of the test steel increased, and the maximum hardness of the heat-affected zone increased with decreasing environmental temperature. The maximam calculated critical constraint stress was 577 MPa at environmental temperatures of -18 ℃ to 15 ℃, and the constraint stress introduced by inclined Y-groove welding crack tests was 588-1 695 MPa, which satisfied the condition of crack formation and led to crack generation and propagation.