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低碳钢形变强化相变的特征 总被引:14,自引:1,他引:14
介绍了低碳钢形变强化相变的基本概念及主要特征.系统的研究工作证实了变形显著地加速了低碳钢过冷奥氏体向铁素体的相变过程.形变强化相变是一个以形核为主导的过程直到相变完成以前,形核始终存在于新相与原奥氏体相界面的高应变区.由于几何空间与成分条件上受到一定的限制,长大及各向异性都不太明显,铁素体晶粒超细化.实验工作还证实了转变动力学呈现明显的3个阶段,它们分别与相变铁素体在原奥氏体晶界上的形核,在铁素体/奥氏体相界前沿高畸变区的形核,及被铁素体晶粒所包围的残存奥氏体上的相变形核等过程相对应。 相似文献
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利用double-hit实验与场发射扫描电镜定量研究了低碳高铌钢(0.032%C-0.089%Nb,HTP钢)粗晶奥氏体(约800 μm)中的形变诱导Nb(C,N)析出规律.结果表明,在1000-900 ℃温度区间变形时,随着形变温度的降低,析出开始(5%析出量)时间逐渐缩短,析出开始时间与温度关系曲线具有C曲线的特征.随着形变温度的降低,析出相颗粒密度逐渐增加而颗粒直径减小,析出动力学满足修正的Avrami方程,Avrami指数约为1.1.析出相主要在位错及位错结等位置优先形核,形成条带状或网状.拟合得到的模型能够预测奥氏体低碳高铌钢的析出开始时间及析出动力学. 相似文献
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The tensile plastic deformation behavior of B2-ordered Fe3Al single crystals at room temperature was systematically investigated. The results show that the mechanical properties are strongly orientation dependent. The plastic elongation of crystals with orientation near [110] is as high as 42%. Slip trace anal ysis shows that although slip planes are found to change among {110}, {11 2} and {123} with the change in orientations, the initial slip planes in a ll c ases are {110}. Five-stage work hardening curve including four linear stages and one parabolic stage is obtained; but not all stages are observed in the a ctual deformation of each crystal. In combination with investigations of disloca tion substructure, it is found that deformations in stage Ⅰ~Ⅲ are corresponding to the motion of two-fold superdislocations. The higher work hardening rate of stage Ⅱ is mainly due to the stronger interactions between primary dislocations and secondary dislocations than those in stage Ⅲ. Deformation in stage Ⅳ involved is not only the motion of two-fold superdislocations but also the slip of dissociated superpartials with APB traps and the formation of APB tube, both of which are attributed to the hardening. Deformation in stage Ⅴ is control led by the cross slip of dissociated superpartials. The dominated softening effect of cross slip reduces the hardening rate and leads to the formation of para bolic stage. 相似文献
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中碳钢过冷奥氏体形变过程中的组织演变 总被引:6,自引:0,他引:6
利用热模拟压缩变形实验研究了不同形变温度以及形变速率下中碳钢过冷奥氏体形变过程中的组织演变规律,探讨了中碳钢珠光体球化以及组织超细化的机理.结果表明:组织演变主要经历了动态铁素体相变、动态珠光体相变以及珠光体的球化3个阶段.为获得亚微米级别铁素体和颗粒状渗碳体弥散分布的复相组织,需要形变温度与形变速率的配合.形变过程中珠光体球化速率比等温球化退火快4个数量级,其原因是在形变过程中产生了高密度位错及大量空位等缺陷,为碳原子的扩散提供了高速率扩散通道,促进了碳原子的扩散.渗碳体粒子在铁素体基体上的弥散分布可用溶解-再析出机制解释. 相似文献
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B_2型Fe_3Al金属间化合物的高温氧化行为 总被引:6,自引:0,他引:6
研究了Fe3Al、Fe3Al(Cr))两种合金在600℃、750℃、950℃的静态氧化行为及其750℃的周期氧化行为,分析了相应的氧化膜结构和形貌,探讨了氧化膜的成长机理。结果表明,由于高温下Fe3Al基金属间化合物表面形成一层致密的A12O3氧化膜而具有优良的抗氧化性能。在950℃高温时,具有比1Cr13不锈钢好得多的抗氧化性能。2at%Cr的加入有利于稳定的α-Al2O3的形成。750℃以下,Fe3Al(Cr)合金的氧化增重低于Fe3Al,前者的氧化膜为纯α-Al2O3,而后者的还含有少量的γ-Al2 相似文献