HQ130钢焊接CGHAZ韧性及TEM分析

Toughness and TEM Analysis of Simulated CGHAZ of HQ130 Steel

采用模拟焊接热循环的方法，研究了ＨＱ１３０高强度钢焊接热影响区粗晶区（ＣＧＨＡＺ）中组织性能的变化，并利用扫描电镜（ＳＥＭ）、透射电镜（ＴＥＭ）和电子衍射技术对焊接ＣＧＨＡＺ冲击断口形态和精细组织结构进行了分析。试验结果表明，ＨＱ１３０高强钢焊接ＣＧＨＡＺ韧性下降的原因除了板条马氏体（ＭＬ）的粗化外，更重要的是上贝氏体（Ｂｕ）组织的形成。通过控制焊接线能量（Ｅ＝１０～２０ｋＪ／ｃｍ）使ＣＧＨＡＺ形成ＭＬ＋（１０～１５）％ＢＬ组织，避免形成贝氏体（Ｂｕ＋Ｂｇ）组织，可使该钢热影响区粗晶区韧性保持在较高水平上。

Microstructure and properties in the coarse grain heat-affected zone (CGHAZ) of HQ130 high strength steel were studied by using the welding thermo-simulation test. Fracture morphology and fine structure in CGHAZ were analysed by means of SEM、TEM and electron diffraction. Experimental results indicated that the important cause resulted in toughness decrease in CGHAZ is the formation of upper bainite ( Bu ) microstructure except the coarsing of lath martensite( ML ). By controlling welding heat input ( E =10～20 kJ/cm) to form mixed microstructure of ML +(10～20)% BL in CGHAZ, preventing to form bainite ( Bu + Bg ), toughness in the CGHAZ can be maintained at higher level.