Experimental investigation on impact toughness in high-temperature of BHW35 steel welded joint

Automatic submerged-arc welding and shielded metal arc welding were employed by H10Mn2NiMoA welding wires,E7015-D2 electrode followed by the postweld heat-treatment systems of normalizing,drawing temper and stress relief annealing.Impact tests on welded joint and base metal at 20℃、100℃、200℃ and 350℃ were carried out.Furthermore,SEM fractograph,metallograph and chemical compositions of welding seam were analyzed.The results indicate that the highest hardness of HAZ was:270.5 HV in SAW;235.2 HV in SMAW,the toughness increases greatly compared with conditions at room temperature.Peak value of impact toughness of SAW is at 100℃,SMAW is at 200℃,which is close to that of base metal.The impact toughness in HAZ is better than that in welding seam,and it is better in SMAW than that in SAW.The impact toughness of welded joint is upward 96.33J at room temperature,it is upward 120 J in welded joint at 350℃,and 186 J in base metal,which indicate that the toughness of welded joint and base metal ars in their best at room and high-temperature.SEM fractograph indicates that all impact fractures exhibit ductile dimple,the better toughness,the more obvious tearing feature of ductile dimple.The larger the ductile dimple is,the more obvious non-uniform distribution is.