Q345超细晶粒钢的焊接性能

Weldability of Q345 ultrafine grain steel

对7.5 mm厚Q345超细晶粒钢板卷进行了两种焊丝(1.2 mm药芯和实芯)3种热输入(4～10 kJ/cm)的系列CO2气体保护焊接试验,研究了焊丝和热输入对焊接接头组织和性能的影响。结果表明,热输入为4～10 kJ/cm的气体保护焊,可得到满足性能要求的焊接接头;热输入为4～6 kJ/cm时,焊接接头粗晶区主要由贝氏体和马氏体构成,且药芯焊丝接头粗晶区马氏体含量高于实芯焊丝接头粗晶区,导致了药芯焊丝接头粗晶区较高的硬度;热输入为10 kJ/cm时,焊接接头粗晶区主要由铁素体构成。拉伸试验和硬度试验表明,母材是焊接接头中的薄弱部位。冲击试验结果表明,焊缝区、热影响区冲击性能与母材在同一水平。

7.5 mm thick ultrafine grained Q345 steel strip was welded by CO2 gas metal are welding using solid wire and flux cored wire under heat inputs of 4, 6 and 10 kJ/cm. Effect of welding wire and heat inputs on microstructure and properties of the welded joint was investigated. The results show that welded joint which exhibits satisfactory property is produced under 4-10 kJ/cm. Coarse grained heat- affected zone （CGHAZ） is mainly composed of bainite and martensite under 4-6 kJ/cm, and martensite volume fraction in CGHAZ of flux cored wire weld is higher than that of solid wire weld, which contributes to higher hardness value of flux cored wire weld CGHAZ. CGHAZ is mainly composed of ferrite under 10 kJ/cm. Tensile and hardness test resuhs show that matrix is the weakest zone. Impact test results show that weld metal and HAZ has similar impact property with matrix.