共查询到19条相似文献,搜索用时 62 毫秒
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利用Gleeble 3500热模拟试验机,建立了X80管线钢焊接热影响区的连续冷却转变曲线(SH-CCT曲线),采用金相分析、显微硬度测试和夏比冲击试验,分析了X80管线钢焊接粗晶区在不同冷却速度下的组织转变和性能变化规律.结果表明:当冷却速度低于0.3℃/s时,粗晶区组织为多边形铁素体和少量珠光体或粒状贝氏体的混合物,具有较好的冲击性能,但硬度较低;当冷却速度为0.3~2℃/s时,粗晶区中的粒状贝氏体和MA岛状组织增多,且晶界模糊,其冲击性能较差;当冷却速度在2~30℃/s时,热影响区组织以粒状贝氏体为主,MA岛状组织的形状和分布均匀,具有优良的冲击性能;当冷却速度大于30℃/s时,随着冷却速度的增加,粒状贝氏体的含量逐渐减小,而贝氏体铁素体的含量逐渐增多,硬度升高,冲击性能下降. 相似文献
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采用焊接热模拟技术和金相显微组织分析技术,对首钢研制开发的X80热轧板卷在不同焊接热循环下的组织和力学性能变化规律进行了深入分析.结果表明,粗晶热影响区是X80管线钢焊接热影响区中冲击韧性较差的区域,存在严重脆化.粗晶热影响区脆化是由于晶粒的粗化以及粒状贝氏体、上贝氏体、M-A组元等非平衡中低温转变产物数量增多造成的,且其冲击韧性随着t8/5的增加而降低.细晶热影响区是X80管线钢焊接热影响区的软化区域,软化程度随着焊接热输入的增加而增加. 相似文献
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采用热模拟试验方法、力学性能测试技术及显微分析技术研究了回火温度对X80钢级热煨弯管组织性能的影响规律。结果表明,当回火温度区间为550~650℃时,贝氏体铁素体及粒状贝氏体中板条宽化现象的增强及沉淀强化效应的降低不利于其强度的提高。位错亚结构的变化,Nb、V、Ti的碳、氮化物对位错及亚晶钉扎作用的降低及板条间M-A组元的逐渐分解等组织因素有利于其韧性的提高。当回火温度升高到700℃时,组织中板条宽化现象进一步增强,部分组织发生再结晶而出现多边形铁素体,以及位错密度的降低导致了材料强度和韧性的快速下降。综合考虑X80热煨弯管的强韧性,适宜的回火温度为650℃×1 h。 相似文献
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研究了热送热装工艺对X80管线钢力学性能和微观组织的影响。结果表明:热送热装板材屈服强度低于室温装炉板材,但韧性高于室温装炉板材;热送热装轧制板材中粒状贝氏体含量较多,而室温装炉轧制板材中板条贝氏体铁素体发达;具有细小针状铁素体是X80管线钢获得良好强度及韧性的前提。 相似文献
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通过热模拟实验, 研究了加热温度、变形温度、变形量、冷却速率和卷取温度对高Nb含量管线钢钢板组织性能的影响, 并确定了工业生产方案。工业试制结果表明: 在1 170~1 200 ℃进行加热保温, 粗轧温度控制在1 020 ℃以上, 变形量控制在30%以上, 精轧入口温度不大于950 ℃, 终轧温度控制在(800±20) ℃, 冷却速率控制在10~30 ℃/s, 卷取温度控制在500~530 ℃, 生产的高Nb含量X80管线钢钢板组织为均匀的针状铁素体, 力学性能优良, ?20、?40 ℃低温冲击功均达到300 J以上, ?15 ℃落锤撕裂试样的剪切面积达到97%以上。 相似文献
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Deng Wei Gao Xiuhua Qin Xiaomei Zhao Dewen Du Linxiu State Key Laboratory of Rolling Automation Northeastern University Shenyang China 《稀有金属材料与工程》2011,(Z3):123-127
Single welding thermal–cycles with different input linear energies (ILE)(15, 20, 30, 40, 50 kJ/cm) and peak temperatures (PT) (900, 1050, 1200, 1300, 1350 ℃) were simulated by MMS-300 to study the correlation of toughness and microstructure in heat-affected zone (HAZ) of a X80 pipeline. The evolution characteristics of microstructure were investigated by OM, SEM and EBSD. The results show that numerous polygonal ferrites and grain boundary ferrites appear, and the sizes apparently decrease as the heat input decreases. Heat input in single welding should be less than 35 kJ/cm to ensure well Charpy impact toughness. The toughness of course grain zone is the lowest when welding heating temperature is 1350 ℃ and it is the weakness part in welded zone. The uniformity of prior austenite grain is worsened as increasing the heat input. Moreover, the characteristics of M-A constituents and high angle grain boundaries (HAGB) are influenced by heat input and PT. In the case of low heat input and PT, higher density of HAGBs, dispersed and fine M-A constituents were observed. Otherwise, with high heat input (≥40 kJ/cm), the effective grain size is almost the diameter of prior austenite grain, and it will decrease the density of HAGB, moreover, coarse M-A constituents which are prone to crack initiation will be generated, thus, the impact toughness of the coarse grain zone will be worsened obviously in welding HAZ. 相似文献
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The intercritical heat-affected zone(ICHAZ) of X80 pipeline steel was simulated by using the Gleeble-3500thermal/mechanical simulator according to the thermal cycle of in-service welding.The microstructures of ICHAZ with different cooling rates were examined,and the hardness,the toughness and corresponding fractography were investigated.Results show that untransformed bainite and ferrite as well as retransformed fine bainite and martensite–austenite(M–A)constituents constitute the microstructure of ICHAZ.The two different morphologies of M–A constituents are stringer and block.Second phase particles which mainly composed of Ti,Nb,C,Fe and Cu coarsened in ICHAZ.Compared with normal welding condition,the toughness of ICHAZ is poor when the cooling time is short under in-service welding condition because of the large area fraction and size of M–A constituents that connect into chains and distribute at the grain boundaries.The Vickers hardness of ICHAZ that decreases with the increase in the cooling time is independent with the area fraction of M–A constituents. 相似文献
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研究了不同成分及终轧温度对X80管线钢组织和性能的影响.结果表明,按照不同Cr/Mo成分比和终轧温度进行试验,试验钢均获得了优异的拉伸性能,但冲击性能稍差,成分对Rt0.5有显著影响,终轧温度对性能影响不显著;在Mo和Cr总含量不变时,随Cr含量增加,屈服强度增加,但韧性有所降低;基体组织为贝氏体,晶粒细小,晶粒度为ASTM13-14级,同时在基体上均匀分布着大量细小的M-A组元;析出相为(Nb,Ti)(C,N),数量较少,颗粒尺寸大多超过150 nm,析出强化效果不大,且其破坏基体的连续性,是导致冲击性偏差的重要原因之一. 相似文献
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郑宏伟 《热处理技术与装备》2016,(6):49-52
通过金相分析、扫描电镜和硬度分析,研究了X80管线钢试样的抗HIC性能。结果表明:X80管线钢中裂纹不是由夹杂物引起的,而是由Mn、P偏析生成了对HIC特别敏感的硬显微带组织;HIC裂纹在准多边形铁素体形核,向外扩展,终止于板条状铁素体。准多边形铁素体的抗HIC性能劣于板条状铁素体,板条状铁素体对裂纹的扩展有明显的阻止作用。 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