摘要
用Gleeble3800热力模拟试验机模拟了12%Cr不锈钢焊接热循环加热过程,利用光学显微镜、场发射扫描电镜及透射电子显微镜研究了其组织转变、晶粒长大规律及析出相.结果表明,加热到900℃以上组织大部分转变为奥氏体,冷却到室温转变为马氏体,1 250℃以上奥氏体全部转变为δ铁素体;1 250℃以下晶粒长大缓慢,1 250℃以上,晶粒随峰值温度的提高和保温时间的延长急剧长大.第二相组织的存在有效地抑制了晶粒长大;母材基体中存在大量细小弥散的铌钛复合碳化物.加热到1 350℃以上,这些碳化物迅速溶解到基体中,不能钉扎晶界和抑制晶粒长大.
Heating process of welding thermal cycle of 12%Cr stainless steel was reproduced with Gleeble 3800 thermo-mechanical simulators.Microstructure transformation,grain growth and precipitating phases were investigated with optical microscope,field emission scanning electronic microscope(FE-SEM) and transmission electron microscope.The following conclusions have been drawn.That the microstructure is almost fully austenite while the heating temperature is above 900℃.This austenite transforms to martensite during the cooling process and is retained down to room temperature.When heating temperature is higher than 1 250 ℃,the austenite is completely transformed to delta ferrite.The grains slightly grow when heating temperature is below 1 250 ℃.At the other hand,if the heating temperature is above 1 250 ℃,grains are dramatically coarsened with an increase of peak temperature and holding time.Grain growth is effectively inhibited by the existing second phase.There are large numbers of finely dispersed complex carbides containing Nb and Ti in base metal matrix.As heating temperature is up to 1350℃,these carbides are dissolved into matrix.Therefore,the pinning grain boundaries and inhibiting grain growth effects of fine particles disappear.
出处
《焊接学报》
EI
CAS
CSCD
北大核心
2011年第6期37-40,114-115,共4页
Transactions of The China Welding Institution
基金
国家自然科学基金资助项目(50734002)
关键词
铁素体不锈钢
焊接热影响区
晶粒长大
析出相
ferritic stainless steel
heat affected zone
grain growth
precipitated phase
