EH36-Z35钢在低温环境中的焊接冷裂纹敏感性

Welding Cold Crack Sensitivity of EH36-Z35 Steel in Low Temperature Environment

通过经验公式和斜Y型坡口焊接裂纹试验研究了50mm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577MPa,而由斜Y型坡口焊接裂纹试验引入的拘束应力为588~1695MPa,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 heataffected 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 588-1695 MPa,which satisfied the condition of crack formation and led to crack generation and propagation.