摘要
通过金相观察、硬度和冲击试验,研究了不同保温时间的焊后热处理(PWHT)对ASTM 4130钢焊接接头显微组织、硬度、低温韧性的影响。结果表明,PWHT后,焊缝组织为铁素体、少量珠光体和碳化物,HAZ组织主要为回火索氏体、铁素体和贝氏体;造成熔合线附近硬度较高、韧性较低的原因是组织的粗化和上贝氏体的形成;随PWHT保温时间的延长,接头硬度降低,韧性改善。这主要是由于保温时间延长,使碳化物逐渐析出,其弥散强化效应和回火索氏体中合金元素固溶强化效应降低,同时,碳化物弥散度的降低也使得接头应力集中程度降低。
The effect of post-weld heat treatment（PWHT） on microstructure,hardness,low temperature impact toughness and fracture morphology of welded joints of ASTM 4130 steel was systematically investigated by using optical microscopy,hardness and impact tests.The results show that the microstructures of weld metal are ferrite,a small mount of pearlite and carbide,and typical heat-affected zone（HAZ） microstructures are comprised of tempered martensite,ferrite and bainite after PWHT.Higher hardness and lower impact toughness in the regions nearby the fusion line is mainly caused by the appearance of coarsen structure and the formation of upper bainite.Hardness levels reduce and toughness levels of welded joints improve with prolonging the soaking time.The main reason may be that the carbide precipitates gradually with prolongation of soaking time,and the effect of dispersion strengthening of carbide and solution strengthening of alloy elements in tempered sorbite is weakening.Meanwhile,the lower dispersity of carbide reduce the stress concentration.
出处
《压力容器》
北大核心
2011年第7期11-16,共6页
Pressure Vessel Technology
基金
国家"863"高技术研究发展计划资助项目(2006AA09A103-6)
