CAJ | 학술논문

通过Gleeble-3500热模拟机对钒(V)含量分别为0.06%和0.02%的X80管线钢进行了峰值温度为1350℃和750℃的焊接热模拟试验,利用硬度计和光学显微镜( OM)分别分析了焊接热模拟试样硬度和试样中马氏体-奥氏体岛状组织( M-A)的数量、尺寸和形貌。利用透射电镜(TEM)对母材、粗晶区和部分相变区中粒子析出进行了表征。结果表明,与0.02%含V量X80管线钢相比,0.06%含V量的X80管线钢由于V含量较高,在受到多道次焊接热循环影响时,部分相变区有较大量碳化钒(VC)粒子析出,明显阻碍位错运动,使其强度明显提高的同时脆性增大、塑性变形难以进行,导致其焊接热影响区韧性下降。
통과Gleeble-3500열모의궤대범(V)함량분별위0.06%화0.02%적X80관선강진행료봉치온도위1350℃화750℃적한접열모의시험,이용경도계화광학현미경( OM)분별분석료한접열모의시양경도화시양중마씨체-오씨체도상조직( M-A)적수량、척촌화형모。이용투사전경(TEM)대모재、조정구화부분상변구중입자석출진행료표정。결과표명,여0.02%함V량X80관선강상비,0.06%함V량적X80관선강유우V함량교고,재수도다도차한접열순배영향시,부분상변구유교대량탄화범(VC)입자석출,명현조애위착운동,사기강도명현제고적동시취성증대、소성변형난이진행,도치기한접열영향구인성하강。
The welding thermal simulation test at peak temperature of 1350 ℃ and 750 ℃ of X80 pipeline steel with vanadium content of 0. 02% and 0. 06% was carried out by Gleeble-3500 thermal simulation machine. The hardness of the welding thermal simulation samples was measured by hardness tester, and the fraction, size and morphology of M-A islands were analyzed by optical microscope. The precipitation particles in the base metal, coarse grain area and partial transition region were characterized by transmission electronic microscope. The results show that, compared to the X80 pipeline steel with 0. 02% vanadium content, large amount of VC particles precipitated in partial transformed region of the X80 pipeline steel with 0. 06% vanadium content when affected by multi-pass welding thermal cycle. The precipitation of VC particles hinders the movement of dislocations which improves the strength and brittleness, makes the plastic deformation difficult to happen, and leads to the decrease of the toughness of welding heat affected zone.