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基于过冷奥氏体动态相变的思想,通过两道次压缩变形结合控制冷却的热模拟轧制工艺,获得不同贝氏体含量及形态的细晶铁素体贝氏体双相钢。通过显微组织观察及力学性能测试,考察了第二相贝氏体特征对双相钢室温拉伸变形行为的影响。研究结果表明,形变后快速冷却可获得无碳板条状贝氏体,较慢的冷速或在贝氏体转变区保温处理可获得粒状贝氏体。贝氏体体积分数大于20%左右的细晶铁素体/贝氏体双相钢具有低的屈服强度,高的抗拉强度,高的伸长率,低屈强比以及连续屈服特性。屈服强度既与铁素体晶粒尺寸相关,也与贝氏体形态和数量相关。板条贝氏体引起的屈服强度提高大于粒状贝氏体,粒状贝氏体具有比板条贝氏体更好的塑性。 相似文献
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《钢铁研究学报》2020,(2)
基于过冷奥氏体动态相变的思想,通过两道次压缩变形结合控制冷却的热模拟轧制工艺,获得不同贝氏体含量及形态的细晶铁素体贝氏体双相钢。通过显微组织观察及力学性能测试,考察了第二相贝氏体特征对双相钢室温拉伸变形行为的影响。研究结果表明,形变后快速冷却可获得无碳板条状贝氏体,较慢的冷速或在贝氏体转变区保温处理可获得粒状贝氏体。贝氏体体积分数大于20%左右的细晶铁素体/贝氏体双相钢具有低的屈服强度,高的抗拉强度,高的伸长率,低屈强比以及连续屈服特性。屈服强度既与铁素体晶粒尺寸相关,也与贝氏体形态和数量相关。板条贝氏体引起的屈服强度提高大于粒状贝氏体,粒状贝氏体具有比板条贝氏体更好的塑性。 相似文献
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通过实验室模拟热处理的方法对TRIP780钢组织与力学性能进行了研究。结果表明:随着钢带运行速度的增加,多边形铁素体体积分数降低,铁素体平均晶粒尺寸增加,贝氏体含量增加。组织中残余奥氏体含量大体呈增长的趋势,残余奥氏体中碳含量基本呈下降的趋势。钢板的抗拉强度逐渐增加,屈服强度和屈强比都是先减小后增大。随着两相区退火温度的提高,铁素体含量逐渐减少,贝氏体的含量逐渐增加,粗大的再结晶铁素体也逐渐被细小的次生铁素体所取代,残余奥氏体量和残奥中的碳含量先随着加热温度的升高而降低,达到一个低谷以后,再随加热温度的升高而增加,抗拉强度、屈服强度和屈强比规律性不是很强。 相似文献
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采用不同的工艺调控技术,实现了一种成分体系可生产具有不同屈强比的经济型冷轧DP780钢,并通过分析力学性能测试结果、TEM和SEM组织形貌特征,得到热轧初始组织、冷轧压下量、连续退火工艺对屈强比的影响。结果表明,当热轧初始组织为F+P(铁素体+珠光体)时,随着平均晶粒尺寸细化至约7.5 μm,屈服强度增加了50 MPa,屈强比由0.48增至0.56;当热轧初始组织变为F+B(铁素体+贝氏体)、以贝氏体为主时,屈服强度达到532 MPa,屈强比增至0.65,同时有利于保证DP780钢的扩孔性和塑性,扩孔率达到86%,特别适用于有扩孔翻边要求的汽车结构件和加强件。此外,适当增加冷轧压下量和降低退火保温温度,均有利于增强基体的强化效应,从而提高屈强比。 相似文献
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为系统研究含钛钢连续冷却相转变和强化机理,利用热模拟试验机、高分辨透射电镜及金相显微镜等设备进行试验。结果表明,低冷速下(0.5~1 ℃/s),组织主要为铁素体和珠光体;冷速逐步增加(1~5 ℃/s),贝氏体组织出现,且贝氏体比例逐渐增加;高冷速后(5~10 ℃/s),组织以贝氏体为主。含钛试验钢强化机制为析出强化和细晶强化。晶粒内部弥散析出10~20 nm的TiN。优化冷速为(1.5±0.5) ℃/s开展20 mm HRB400E钢筋工业试制,屈服强度不小于430 MPa,断后伸长率不小于20%,最大力总伸长率不小于15%,强屈比不小于1.4。 相似文献
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Le-yu ZHOU Bo JIANG Tian-hao CUI Dan ZHANG Jian-zhong HE Ya-zheng LIU 《钢铁研究学报(英文版)》2014,21(12):1111-1115
Two kinds of C-Si-Mn-Cr series tested steels were designed to obtain dual phase microstructures of ferrite (F) +martcnsite (M) or ferrite (F)-bainite (B) with different mechanical properties. Effects of strengthening phase on yielding and fracture behaviours during uniaxial tension of dual phase steel were discussed. Compared with hot-rolled martensite dual phase steel, ferrite-bainite dual phase steel has high ratio of yield strength to tensile strength (YS/TS) and low elongation. During necking process of uniaxial tension, microvoids of ferrite-martensite steel are generated by fracture of ferrite/martensite boundary or martensite islands with irregular shape. But ferrite matrix elongated remarkably along deformation direction, and strengthening phase also coordinated with ferrite matrix. Compatible de formation between ferrite and bainite is distinct. Ferrite-bainite dual phase steel has fine and less microvoid, and phase boundary of ferrite and bainite is beneficial for restraining generation and extending of microvoid. 相似文献
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以高氢冷却工艺连退生产线为基础,以 900 MPa 级冷轧马氏体超高强钢为研究对象,研究了连续冷却相变区转变规律和连退快速冷却工艺对钢的力学性能和显微组织的影响。结果表明,连续冷却相变区由先共析铁素体转变区、贝氏体转变区和马氏体转变区组成,随着冷却速度的增加,先共析铁素体含量逐渐下降,贝氏体和马氏体含量逐渐上升,当冷却速度大于 40 ℃/s 时,不再有先共析铁素体生成;当冷却速度大于 80 ℃/s 时,则完全进入马氏体转变区。随着连退快冷工艺中冷却速度的增加,钢的屈服强度、抗拉强度和屈强比逐渐增加,断后伸长率逐渐下降。当冷却速度为 50 ℃/s 时,钢的屈服强度、抗拉强度和断后伸长率就已经达到了 900 MPa 级冷轧马氏体超高强钢的力学性能要求。 相似文献
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Dong-Jun Choi Tae-Yeong Kim Hyun-Uk Hong Joonoh Moon Chang-Hoon Lee Dong-Ik Kim Jae-Hyeok Shim Heung Nam Han Young-Su Lee 《国际钢铁研究》2023,94(2):2200103
Herein, a series of low-Mo (0.2 wt%) fire-resistant steels with varying amounts of Ti (0.008–0.13 wt%) are investigated to study the effects of Ti on yield strength at elevated temperatures. At room temperature (RT), precipitation strengthening by nanoscale TiC precipitates is found to be the major factor for the enhanced strength. The amount of TiC precipitates and both the yield and tensile strengths increase monotonically with the Ti content. However, the yield strength ratio (YS at 600 °C divided by YS at RT) of the steel with the highest Ti content (0.13 wt%) is significantly reduced to 0.6. In contrast, the YS ratio of the steels with Ti content in the range of 0.008–0.087 wt% remains above 0.7 and increases with Ti content. The difference between the steels lies in the B content and the resultant bainite volume fraction. The steel with 0.13 wt% Ti does not contain B and has only 4% bainite, whereas the other steels contain 20 ppm B and approximately 60% bainite. Hence, a microstructure with a sufficient fraction of bainite is required to ensure strength at elevated temperatures. The properties can be further improved by Ti precipitation strengthening. 相似文献
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采用传统的高强钢焊接材料焊接690 MPa级低碳铜沉淀强化钢时,仍需严格控制热输入、预热温度、层间温度,这使得低碳铜沉淀强化钢的优良性能和可节约生产成本的优势得不到很好地发挥。通过采用光学显微镜(OM)、扫描电子显微镜(SEM)、透射电镜(TEM)等表征方法,研究了不同质量分数的Si/Mn/Ni配比对690 MPa级超低碳贝氏体(ULCB)熔敷金属的组织及强韧性能的影响,为690 MPa级低碳铜沉淀强化钢配套的焊接材料的工程化应用提供一定的技术支持和积累。结果表明,690 MPa级超低碳贝氏体(ULCB)熔敷金属组织主要由板条贝氏体、粒状贝氏体和针状铁素体组成。当Si质量分数为0.16%、Mn质量分数为1.46%时,熔敷金属组织细化,冲击韧性得以提升,但Si含量过低易使贝氏体铁素体呈块状,导致韧性提升有限。而当Si质量分数为0.29%、Mn质量分数为1.02%时,Ni含量增加,贝氏体铁素体板条呈细长条状,显微组织相互交错分布,使熔敷金属冲击韧性显著改善。相变位错强化受贝氏体开始转变温度(Bs)影响,这是影响ULCB熔敷金属强度的主要原因。ULCB熔敷金属中夹杂物主要分布在贝氏体铁素体的板条亚结构间,少量成为针状铁素体的形核质点,促进针状铁素体形核,因此,对熔敷金属中的夹杂物进行控制,可进一步发挥超低碳贝氏体熔敷金属的潜力,提高其韧性。 相似文献
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《钢铁研究学报(英文版)》2011,(Z1):707-711
A low carbon Nb-microalloyed high deformability pipeline steel with X100 grade has been processed by TMCP and followed two-stage cooling process.The microstructure is characterized by ferrite/bainite multiphase.The effective grain size is 1.85μm in average.The volume of ferrite is about 10-15% and the grains sizes are mostly less than 5μm.The bainite consists of granular-bainite and lath-bainite,with M/A islands finely dispersed.The longitudinal tensile yield strength,uniform elongation,yield ratio are 647MPa,7.6% and 0.78,respectively.Ferrite/bainite multiphase have large strain hardenability that resulting high strength and high deformability combination.Precipitation of Nb also improves the strength and uniform deformability by precipitation strengthening and grain refinement. 相似文献
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利用超低碳和微合金化的成分设计,采用TMCP工艺,充分利用晶粒细化和针状铁素体与粒状贝氏体组织强化、下线堆垛缓冷24h等手段,保证热轧状态达到该钢种需要的屈服强度、伸长率,进而去掉热处理调质及回火工艺,同样在工业试制条件下得到韧性良好、屈服强度为570 MPa级的超低碳贝氏体钢。 相似文献
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