共查询到19条相似文献,搜索用时 156 毫秒
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结合12~33mm厚X70管线钢落锤试验结果,利用光学显微镜和扫描电镜研究和分析不同厚度落锤试样的组织演变规律及组织对落锤性能的影响。结果表明:随着钢板厚度的增加,钢的组织由彼此交织在一起的针状铁素体、多边形铁素体/准多边形铁素体演变成粒状贝氏体+少量针状铁素体/多边形铁素体,碳化物的析出数量和析出尺寸随之增加。具有交织在一起的非等轴状AF+PF/QF混合组织的试样落锤性能优于以晶粒粗大粒状贝氏体为基体组织的试样的落锤性能。通过控制M/A岛形态和分布可以提高钢的落锤性能。 相似文献
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介绍了韶钢的Q550高强度工程机械用钢的生产情况,采用低碳,Nb、V、Ti、Mo等微合金化的成分设计,结合控轧控冷、离线回火工艺生产了厚度达到30 mm的Q550钢板,钢板的力学性能满足交货需要。利用光学显微镜、扫描电镜分析了钢板的组织情况,并使用透射电镜结合能谱仪分析了钢板的析出相情况,分析结果表明Q550钢板的回火组织为粒状贝氏体、针状铁素体以及少量多边形铁素体,晶粒细小、均匀,析出相主要是Nb、Ti的碳氮化物,V、Cr对Q550的析出强化没有贡献。 相似文献
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采用不同V、Cr含量,结合Nb、Ti、Mo等微合金化的成分设计,控轧控冷、离线回火工艺生产了30 mm厚度规格的低碳贝氏体钢板,钢板的组织为粒状贝氏体、少量针状铁素体以及少量多边形铁素体,钢板的力学性能满足交货需要.使用透射电镜结合能谱仪分析了钢板的析出相情况,结果表明钢板的析出相主要是Nb、Ti的碳氮化物,析出相含有微乎其微的V,而没有Cr;Nb、Ti通过析出对钢板起到析出强化作用,V、Cr在钢中起固溶强化作用,对强度贡献较小. 相似文献
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非调质型15万m~3石油储备罐体用610MPa高强度钢板轧制和热处理工艺研究与实践 总被引:1,自引:0,他引:1
主要采用热模拟技术研究了不同终轧工艺和不同回火温度对石油储备罐体用高强度钢板JGR610E显微组织的影响,并利用金相和萃取复型等分析方法对不同工艺下的显微结构和碳化物进行了分析。结果表明,JGR610E钢在860℃左右终轧温度、20℃/s冷却速度下可以获得板条状低碳贝氏体组织,经过620℃回火后得到具有良好强韧性能的板条贝氏体和针状铁素体混合组织,其析出相主要有两类,尺寸在300 nm左右的为含有Fe和Mn的MxCy型碳化物,尺寸范围在50~100 nm的为含有Ti和Nb的MC型碳化物,且在该回火温度下,有大量的尺寸范围在几个纳米至十几个纳米尺寸的Ti(CN)析出。 相似文献
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为了探究Nb Ti钢合适的焊接热输入范围并指导实际焊接工艺过程,利用Formastor F Ⅱ型自动相变测量仪和Gleeble 3800热模拟试验机研究了焊接热输入对Nb Ti钢相变温度、组织和韧性的影响规律。结果发现,当冷却速度大于6 ℃/s时,Nb Ti钢模拟CGHAZ的组织为粒状贝氏体和板条贝氏体,且随着冷却速度降低,板条贝氏体含量下降,粒状贝氏体含量增加;当冷却速度为6 ℃/s时,出现晶界铁素体组织,且随着冷却速度继续下降,晶界铁素体含量增加;当冷却速度不大于0.6 ℃/s时,组织为完全的铁素体和珠光体。随t8/5时间的增加,M A含量先增加后减少,在t8/5为178 s时,M A面积百分数达到最大值,为5.1%。当t8/5时间为144~178 s时,M A组元的含量是控制Nb Ti钢模拟CGHAZ区韧性的主要因素;当t8/5为256 s时,M A组元含量下降,粗大的晶界铁素体是控制Nb Ti钢模拟CGHAZ韧性的因素。 相似文献
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用Gleeble-1500D热模拟试验机和电子显微镜研究了在950~750℃不同温度下变形50%后0.05C- 0.13Nb钢的组织和析出相。结果表明,随变形温度由950℃下降至750℃,0.05C-0.13Nb钢中多边形铁索体含量(体积分数)由20%增至80%,多边形铁素体晶粒尺寸由9μm降至4μm;变形后的组织由多边形铁索体、粒状贝氏体和1~3μm马氏体/奥氏体岛组成;钢中的析出物为1~10 nm的Nb(C,N),随变形温度降低析出物数量增加。 相似文献
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为了研究微观组织、M/A岛体积分数和长宽比对管线钢低温韧性的影响,用OM、SEM、EBSD和TEM等多尺度手段对材料进行了表征。结果表明,不同冷却速度工艺下均得到针状铁素体(AF)+准多边形铁素体(QF)+M/A岛+粒状贝氏体(GB)的组织结构。但随着冷却速度的增加,组织得到显著细化,有效晶粒尺寸由3.21降低到2.88 μm。M/A岛体积分数从11.2%降低到5.8%,M/A岛长宽比也从3.5降低到1.2。在温度不低于-40 ℃时,随着有效晶粒尺寸减小和M/A岛尺寸、长宽比的减小,管线钢的低温韧性大幅提高。但在温度降低到-80~-60 ℃时,以马氏体为主的类圆形M/A岛易脆化断裂,造成材料在M/A岛体积分数最低和长宽比最低时冲击韧性出现最低值,管线钢的低温韧性与大角度晶界所占的百分比没有直接关系。针对试验用高强管线钢,在冷却速度为20 ℃/s、M/A岛体积分数为9.8%左右、长宽比为2.5时,材料具有韧性优异的综合性能。 相似文献
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冷却工艺对超低碳贝氏体钢强韧性影响的研究 总被引:11,自引:0,他引:11
研究了一种含有Cu、Ni、Mo、Nb、B等元素的超低碳贝氏体钢,以搞清楚其在不同的热机械处理 弛豫-析出-控制相变技术 回火工艺(TMCP RPC T)条件下组织和强韧性能的变化规律.实验室研究和工业试制表明,随着工艺制度的不同,钢的显微组织表现为粒状贝氏体和板条贝氏体的比例、形态、尺寸不同;在一定的冷却速度下,轧态钢的屈服强度、抗拉强度和屈强比随终冷温度的降低呈现上升趋势;回火后钢的屈强比较热轧态有所提高.试验条件下,回火温度对Nb析出数量的影响不明显,加热时Nb的固溶程度对该钢的最终组织有明显影响;采用TMCP RPC、TMCP RPC T工艺路线,通过调整工艺参数,能够获得不同性能组合的钢板,实现高性能钢种的柔性化设计. 相似文献
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Dynamic CCT (continuous cooling transformation) curves and effects of microstructures and M/A islands of X100 hot rolled strip on mechanical properties were studied by means of a thermal simulator, a scanning electron mi- croscope (SEM), a transmission electron microscope (TEM), a digital micro-hardness tester and Image-Pro Plus analysis software. The results show that high contents of C and Mo can make transformation lines of acicular ferrite and bain- ite shift rightward. High Mo tested strip has higher strength and micro-hardness and lower toughness than the other one because lath bainite appears instead of quasi-polygonal ferrite. Tested strip with granular bainite, lath bainite and M/A islands has better mechanical properties and in the microstructures lath bainite content is around 36.50% and M/A islands are fine and disperse in the matrix. 相似文献
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A new hot-rolled low carbon air-cooling bainitic steel containing 0.02%Nb has been developed based on alloying design of the grain boundary allotriomorphic ferrite (FGBA)/ granular bainite (BG) duplex steel.The as-rolled microstructure and mechanical properties of 0.02%Nb bainitic steel were investigated by tensile test, X-ray diffraction(XRD),Optical Microscopy (OM), scanning electron microscopy (SEM) ,and Transmission electron microscopy(TEM). The results show that (1) The addition of 0.02% niobium improves the strength obviously without sacrificing toughness of the FGBA/BG steel. Compared with Non-Nb FGBA/ BG steel, 0.02% Nb increases the tensile strength and yield strength about 20% (From 780Mpa to 937Mpa)and 17%(From 557Mpa to 650Mpa) respectively, remaining 18% elongation and 83J Akv. (2) Small addition of Nb(0.02%) not only refines the allotriomorphic ferrite grain but also promotes the nucleation of intragranular ferrite, both of which in turn contribute to the refinement of granular bainite cluster including its ferrite platelets and M-A islands. Compared with Non-Nb steel, the volume fraction of M-A island in 0.02%Nb steel increases from 21% to 31%, and the average size of M-A island decreases from 1.2μm to 0.95um.(3)There is hardly any Nb(C,N) has been observed in 0.02%Nb steel. It is suggested that the strengthening effect of 0.02%Nb can be mainly attributed to the influence of the segregation of Nb to γ/α phase boundaries(solute drag-like effect) on the phase transformation rather than the precipitation strengthening of Nb(C,N). 相似文献
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Hyo Kyung Sung Sang Yong Shin Byoungchul Hwang Chang Gil Lee Sunghak Lee 《Metallurgical and Materials Transactions A》2013,44(1):294-302
In this study, four low-carbon high-strength bainitic steel specimens were fabricated by varying finish cooling temperatures and cooling rates, and their tensile and Charpy impact properties were investigated. All the bainitic steel specimens consisted of acicular ferrite, granular bainite, bainitic ferrite, and martensite-austenite constituents. The specimens fabricated with higher finish cooling temperature had a lower volume fraction of martensite-austenite constituent than the specimens fabricated with lower finish cooling temperature. The fast-cooled specimens had twice the volume fraction of bainitic ferrite and consequently higher yield and tensile strengths than the slow-cooled specimens. The energy transition temperature tended to increase with increasing effective grain size or with increasing volume fraction of granular bainite. The fast-cooled specimen fabricated with high finish cooling temperature and fast cooling rate showed the lowest energy transition temperature among the four specimens because of the lowest content of coarse granular bainite. These findings indicated that Charpy impact properties as well as strength could be improved by suppressing the formation of granular bainite, despite the presence of some hard microstructural constituents such as bainitic ferrite and martensite-austenite. 相似文献
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利用Gleeble-3500热模拟试验机、扫描电镜、透射电镜、电子背散射衍射技术等手段研究V对700 MPa级高强度汽车大梁钢组织细化的影响.在冷却速度2~7℃·s-1时,显微组织为针状铁素体+粒状贝氏体组织.V添加提高粒状贝氏体体积分数,细化粒状贝氏体组织,并明显降低粒状贝氏体中M/A岛的尺寸.与无V钢相比,含V钢中大角度晶界比例提高18.2%,对提高钢的韧性有利.由于C含量过低,在实验钢中未观察到单独的VC析出,由此推测V主要固溶在基体中,以合金化方式促进钢的贝氏体相变,使组织得到有效细化. 相似文献