1000 MPa级高强钢国产自研实心焊丝焊接工艺研究

Research on the Welding Process of 1000 MPa Grade High Strength Steel Self-developed Solid Wire

针对国产自研的1 000 MPa级高强钢实心焊丝的熔化极气体保护焊工艺进行了系统性试验与分析。深入探讨了焊接电流和预热温度对接头微观组织、硬度分布以及力学性能的影响。研究发现,焊缝金属组织主要由马氏体构成,且随着焊接电流和预热温度的增加,贝氏体的含量相应增加;热影响区(HAZ)呈现出明显的硬化和软化趋势,细分为粗晶区、细晶区和不完全重结晶区;硬度在细晶区达到最高值,临界热影响区最低;在相同的预热温度下,随着焊接电流的增加,焊接接头的抗拉强度和冲击韧性呈现先增加后减少的趋势;而在相同的焊接电流下,抗拉强度和冲击韧性随预热温度变化的规律性不明显。当焊接电流为260 A,预热温度为100℃时,接头的力学性能最优,其抗拉强度高达1 088 MPa,-40℃时的冲击韧性达到47.8 J。

This study conducted a systematic experimental and analytical investigation of the gas shielded welding process using domestically developed solid wire for 1000 MPa grade high-strength steel.Employing metallographic microscopy,scanning electron microscopy,microhardness testing,and room temperature tensile tests,the research delved into the effects of welding process parameters,including welding current and preheating temperature,on the microstructure,hardness distribution,and mechanical properties of the welded joints.The study found that the weld metal microstructure is primarily composed of martensite,with the content of bainite increasing as the welding current and the preheating temperature increases.The heat-affected zone(HAZ)of the welded joint exhibits distinct hardening and softening trends,divided into coarse grain areas,fine grain areas,and incompletely recrystallized areas.Hardness testing results indicate that the hardness is highest in the fine grain area of the HAZ and lowest in the critical heat-affected zone.Mechanical property analysis reveals that at the same preheating temperature, the tensile strength and impact toughness of the welded joint increase and then decrease as thewelding current increases;while at the same welding current, the variation of tensile strength and impact toughness with differentpreheating temperatures is not significant. Notably, when the welding current is set to 260 A and the preheating temperatureto 100 ℃, the welded joint exhibits the optimal comprehensive mechanical properties, with a tensile strength of upto 1 088 MPa and an impact toughness of 47.8 J at -40 °C.