Effect of annealing time on microstructure and phase transformation of SMAW welded joint for T91 steel

LI Zizhou; FENG Keyun; LIU Peng

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Effect of annealing time on microstructure and phase transformation of SMAW welded joint for T91 steel
Vol. 49, Issue 8, Pages: 91-94(2019)
Published：2019
DOI：
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DOI：

LI Zizhou, FENG Keyun, LIU Peng. Effect of annealing time on microstructure and phase transformation of SMAW welded joint for T91 steel[J]. Eletric Welding Machine2019, 49(8): 91-94. DOI：

摘要

采用金相、硬度、扫描电子显微分析(SEM)、能谱分析(EDS)及X射线衍射分析(XRD)试验方法

对760℃+不同保温时间退火处理前后T91耐热钢焊条电弧焊(SMAW)接头显微组织及相变展开研究

研究发现

经760℃+不同保温时间的退火处理后

T91耐热钢SMAW焊接接头硬度明显降低

硬度分布从母材到热影响区呈下降趋势

焊缝区(WZ)显微组织由粗大的板条马氏体转变成细小均匀的片状马氏体或针片状马氏体

经6 h退火保温处理后

以颗粒状弥散分布在晶界

马氏体针状界及马氏体内部的第二相粒子强化作用明显

此时材料的性能相对比较优异。

Abstract

Optical microscope

micro-hardness tester

scanning electron microscope（SEM）

energy dispersive spectrometer（EDS） and X-ray diffractometer（XRD） were applied to analyze the microstructure and phase transformation of Shielded Metal Arc Welding（SMAW） joint for T91 heat resistant steel under 760 ℃+different holding time of annealing treatment. The test results show that the hardness of welded joints decreases obviously

and the hardness distribution decreases from base metal to heat affected zone by different holding time of annealing treatment. In the same time

the microstructure in the weld zone transforms from lath martensite to acicular martensite or plate martensite with different holding time of annealing treatment. Fine dispersed precipitated phases are mainly distributed in grain boundaries and martensitic boundaries and interior after annealing treatment of holding 6 h. The properties of materials are relatively excellent by second phase strengthening.