Mg含量对高强海工钢大线能量焊接性能的影响

Effect of Mg Content on the Weldability of High Strength Offshore Steel Plates for High Heat Input Welding

本文研究了Mg含量对EH550级别海洋工程用钢150 kJ/cm大线能量焊接热影响区夹杂物、组织及低温冲击韧性的影响,结果表明:随着钢中Mg含量由0.000 2 wt.%升高至0.002 9 wt.%,夹杂物数量密度由230个/mm^(2)增至325个/mm^(2),夹杂物平均尺寸均在1.70μm左右;主要夹杂物类型由MgO+Al_(2)O_(3)+TiN+MnS转变为MgO+TiN+MnS;原奥氏体晶粒平均尺寸由51.31μm减小至36.60μm;在-40℃条件下的夏比冲击吸收功由117 J增加至157 J。通过Mg脱氧细化奥氏体晶粒,减小板条状贝氏体组织中的马奥组元尺寸,有利于改善高强海洋工程用钢的大线能量焊接热影响区低温冲击韧性。

The effect of Mg content on the inclusions, microstructure and low temperature impact toughness of heat-affected zones(HAZs) for EH550 grade offshore steel plates after 150kJ/cm high heat input welding was studied. The results showed that with the increase of Mg content from 0.000 2 wt.% to 0.002 9 wt.%,the number density of inclusions increased from 230 mm^(2) to 325mm^(2). The average sizes of inclusions were about 1.70 μm. The main inclusions types were changed from MgO + Al_(2)O_(3)+ TiN + MnS to MgO + TiN + MnS. The average size of prior-austenite grain was decreased from 51.31 μm to 36.60 μm. The-40 ℃ Charpy impact energy of HAZs was increased from 117 J to 157 J. Refining the austenite grains by Mg deoxidation and then decreasing the sizes of M-A among lath bainite is beneficial to improve the HAZ low-temperature impact toughness of high strength offshore steel plates for high heat input welding.