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通过焊接热模拟试验研究了钢中Mg含量对焊接热影响区夹杂物及组织的影响。研究结果表明,随着钢中Mg质量分数由0增加至27×10-6再到37×10-6,氧硫化物复合夹杂类型变化为Al_2O_3-Mn S→MgO+Al_2O_3+Ti2O3-Mn S→MgO-Mn S;氧硫化物复合夹杂数量增加、尺寸减小。焊接热影响区组织变化为晶界铁素体+魏氏组织+侧板条铁素体→晶界铁素体+晶内针状铁素体→块状铁素体。利用Mg脱氧工艺生产的钢板经过400 k J/cm大线能量焊接后热影响区的-20℃冲击功都在100 J以上。
The influence of Mg content in steel on the inclusions and microstructure of HAZ was studied by means of welding thermal simulation. The results show that with the increase of Mg content in steel from 0 to 27 × 10-6 to 37 × 10-6, the type of complex oxide-oxysulfide changes into Al_2O_3-MnS → MgO + Al_2O_3 + Ti2O3-MnS → MgO-Mn S; the amount of oxysulfide compound inclusions increases, the size decreases. The heat affected zone (HAZ) microstructure changes are grain boundary ferrite + Westend + side lath ferrite → grain boundary ferrite + intragranular acicular ferrite → massive ferrite. The impact energy at -20 ℃ in the heat-affected zone of the steel sheet produced by Mg deoxidation after welding at 400 kJ / cm is above 100 J.