摘要
通过金相、碳复型萃取、投射电子显微镜(TEM)、扫描电子显微镜(SEM)、X射线能谱(EDS)等方法对600℃服役约45 000h的12%Cr马氏体钢焊缝金属的显微组织结构进行了分析,研究影响12%Cr马氏体钢高温服役退化的因素。结果表明,该12%Cr马氏体钢焊缝金属的组织结构较服役前发生很大变化:(1)大量Laves相在晶界和板条界沉淀析出呈链状分布;(2)M23C6型碳化物发生粗化;(3)Z相以消耗MX为代价在晶界和亚晶界沉淀析出。沉淀相粗化导致强化效果下降,阻止亚晶长大的能力下降。
Aiming at finding out the relationship between microstruetural evolution and degrada- tion of creep rupture strength,the microstructural evolution of the weld joint metal 12%Cr mar- tensite steel used for superheater header after 45 000 hours service at 600 ℃ has been investiga- ted,by means of carbon replica extraction method, transmission electron microscopy （TEM） and energy dispersive spectroscopy （EDS）. The results show that, the microstructure of weld joint metal 12%Cr martensite steel after 45 000 hours service at high temperature changed significant- ly： （1） the Laves phase precipitated along the martensite lath boundaries and the prior austenite grain boundaries;（2） the M2BC6 carbides coarsened; （3） the Z phase formatted around the prior austenite grain boundaries and the packet boundaries by consuming the MX carbonitrides. Coarsen of the precipitated phase resulted in decrease in strengthening effect and inhibiting ability for sub- grain＇s growth. Furthermore,the precipitation of Z phase consumed large amount of MX carboni- trides,causing the tempering martensite recovered and the subgrain structure coarsened,which af- fected the high temperature creep rupture strength of the 12%Cr martensite steel seriously.
出处
《热力发电》
CAS
北大核心
2014年第1期69-73,共5页
Thermal Power Generation
