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用热模拟方法研究了氮含量对钒微合金钢粗晶热影响区(CGHAZ)的组织和性能的影响。结果表明,氮含量为0.0031%或0.021%时,CGHAZ的韧性较差。氮含量0.0031%时CGHAZ中有少量的Ti(C,N),晶界铁素体(GBF)较少,晶内有大量尺寸较大的侧板条铁素体(FSP),解理裂纹沿FSP的直线扩展使其韧性较差。氮含量0.021%时在CGHAZ中生成了较为粗大的(Ti, V)(C, N)和GBF,解理裂纹沿GBF扩展使其韧性较差。氮含量为0.012%时低温韧性较好,在CGHAZ中生成了大量细小的(Ti, V)(C, N)粒子,且GBF尺寸相对较小,晶内有大量的针状铁素体(AF)。这些因素都有利于阻止裂纹扩展,使其低温韧性显著提高。 相似文献
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G. Huang X. L. Wan O. Isayev O. Hress I. Rodionova 《Materials Science & Technology》2017,33(5):602-614
The effects of Cu content on microstructure and impact toughness in the simulated coarse-grained heat-affected zone (CGHAZ) of high-strength low-alloy steels were investigated. It has been observed that the microstructure in the simulated CGHAZ of Cu-free steel is dominated by a small proportion of acicular ferrite and predominantly bainite with martensite–austenite constituent. Whereas, in the 0.45 and 1.01% Cu-containing steels, the acicular ferrite increased significantly due to the effective nucleation on intragranular inclusions with outer layer of MnS and CuS. The formation of acicular ferrite is attributed to superior high heat-affected zone impact toughness in the 0.45% Cu-containing steel. Furthermore, the increasing martensite–austenite constituent and ε-Cu precipitates in the simulated CGHAZ of 1.01% Cu-containing steel caused degradation in impact toughness. 相似文献
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Microstructure evolution and corrosion resistance in simulated CGHAZ of X80 high-deformability pipeline steel
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In this study, the microstructure evolution and corrosion resistance in 0.5M Na2CO3-1 M NaHCO3 solution of X80 high-deformability (X80HD) pipeline steel coarse-grained heat-affected zone (CGHAZ) with several heat input levels were investigated. It is shown that the microstructure of CGHAZ changes from bainite ferrite to granular bainite as the heat input increasing. In addition, the corrosion resistance and the stability of passive film of base material are better than those of CGHAZ with several heat input levels. Too small or too big heat input is inadvisable and better corrosion resistance of CGHAZ is attained when heat input is 30kJ/cm. 相似文献
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In general, the weld thermal cycle results in significant changes in microstructure and mechanical properties of the weld heat affected zone ( HAZ) . The microstructure, microhardness and low temperature impact toughness of HAZ for X100 pipeline steel were studied by means of welding thermal simulation. Influence of cooling time on the microstructure and properties in coarse-grained heat affected zone ( CGHAZ) was investigated. The results illustrated that polygonal ferrite and a small amount of granular bainite were obtained when the cooling time t 8/5 is larger than 1 500 s. Mainly granular bainite was formed when the cooling time t 8 / 5 is in the range of 1 500 s to 100 s. Bainite ferrite was observed when the cooling time is smaller than 60 s. Martensite appeared in the CGHAZ with the 20 s cooling time. The value of microhardness in the CGHAZ was higher than that of base metal ( BM) when the cooling time t 8/5 is smaller than 100 s. The CVN absorbed energy in the CGHAZ was higher than the value of BM when the cooling time t 8/5 is smaller than 30 s 相似文献
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X70管线钢在役焊接局部脆化区的组织及精细结构 总被引:2,自引:0,他引:2
采用焊接热模拟试验研究了X70管线钢在役焊接粗晶区和临界粗晶区的显微组织及其精细结构,并和常规焊接进行了对比.结果表明,X70管线钢在役焊接粗晶区和临界粗晶区的组织在类别上与常规焊接相差不大,主要都是粒状贝氏体和贝氏体铁素体,不同的只是数量的多少和尺寸的大小.透射电镜下,在役焊接和常规焊接的粗晶区与临界粗晶区的主要形貌都是铁素体板条和分布在板条之间或板条基体上的岛状物,铁素体板条的亚结构都是高密度位错.在役焊接粗晶区和临界粗晶区的铁素体板条宽度都比常规焊接的要小,位错密度都比常规焊接的要高. 相似文献
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采用Gleeble-3500热模拟试验机和热处理炉对T23钢进行了焊接热模拟和焊后热处理试验,并运用金相、硬度、扫描电镜试验,研究了不同的焊后热处理温度对T23钢热影响粗晶区(CGHAZ)微观组织的影响.结果表明,焊态热模拟CGHAZ组织类型主要是板条马氏体和贝氏体的混合组织,具有很高的硬度.随着热处理温度的提高,CGHAZ晶粒趋于细化,硬度逐渐降低.但在700℃下,晶界出现了微孔洞和含W碳化物,硬度剧烈升高,应避免在此温度进行热处理.最后确定T23钢合理的焊后热处理为750℃×2h,可以获得良好的强韧性匹配. 相似文献
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摘要:采用Ca、Mg处理工艺研究不同夹杂物粒子对200kJ/cm大线能量焊接低合金高强度钢CGHAZ冲击韧性的影响,对各个试样CGHAZ的显微组织,晶粒尺寸和冲击功进行观察和分析。试验结果表明,在低合金高强度钢CGHAZ中,Mg处理钢的冲击性能明显高于Ca处理钢,主要原因是含Mg夹杂物粒子析出能力比含Ca夹杂物粒子强,在焊接过程中,含Mg夹杂物粒子对CGHAZ组织的钉扎作用更加显著;同时提高针状铁素体的含量,延长裂纹扩展路径,提高断裂时吸收的能量,使样品韧性得到提升。 相似文献
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