含钒汽车大梁钢P510L连续冷却时的组织转变

用MMS-200热力模拟试验机研究了含钒汽车大梁钢P510L在连续冷却条件下的组织演变规律,采用热膨胀法结合金相法建立了P510L的静态CCT曲线和动态CCT曲线,分析了变形条件、冷却速度对P510L显微组织的影响.结果表明:奥氏体低温区的变形促进了铁素体相变和珠光体相变,抑制了贝氏体相变;并且随着冷却速度的增大,铁素体的量减少,贝氏体的量增多.     

用人工神经网络分析Ni含量对新型空冷贝氏体钢CCT图的定量影响

用人工神经网络模型分析了Ni含量对新型空冷贝氏体钢的连续冷却转变(CCT)图的定量影响.首先测试了神经网络模型的预测性能,对几种新型空冷贝氏体钢CCT图的预测结果和实测结果的比较说明我们设计的ANN模型具有较高的预测精度和可靠性.然后用人工神经网络模型分析了Ni含量对CCT图的定量影响.结果表明,Ni含量增加会使钢的奥氏体形成温度下降,推迟高温转变、中温转变和马氏体转变.人工神经网络模型的计算结果与材料科学理论相符.     

Oxygen-contact charge transfer complexes in organic bicomponent systems

The O₂-CCT absorption spectra of bicomponent systems were measured. The influences of various organic compounds as well as the component concentration on the O₂-CCT formation ability were investigated. The results show that if the difference of O₂-CCT formation ability between the two components is rather large, such as the benzene/ isopropyl ether system, only the O₂-CCT absorption of benzene appears, which arises from its higher O₂-CCT formation ability. If the difference of O₂-CCT formation ability is small, such as the isopropyl ether/ethanol system and the dioxane/isopropyl ether system, it is rather easy to form a dynamic equilibrium of two O₂-CCT between the two components, then only one absorption peak appears in the whole concentration range as a result of the repeated addition of the two kinds of O₂-CCT absorption. If the difference of O₂-CCT formation ability is in medium compared with the two cases above, such as the dioxane/ethanol system, there are two kinds of₂-CCT absorption of dioxane and ethanol in the same system in the form of an equilibrium, then two absorption peaks can be detected in the middle concentration range as a result of the repeated addition of the two kinds of₂-CCT absorption.     

SCM435钢奥氏体连续冷却转变行为

利用热模拟试验机对SCM435钢的奥氏体连续冷却转变(CCT)曲线进行了测定和分析.结果表明:SCM435钢对冷速极为敏感,在冷却速度为005℃/s时,可以得到铁素体、珠光体及少量贝氏体组织;当冷速增加到1℃/s时,铁素体转变结束,同时开始产生少量马氏体组织.在实际生产中,通过与模拟预测相结合来控制冷却,抑制块状先析铁素体的生成,同时避免马氏体的大量产生,生产出冷镦性能及球化效果较为理想的基体组织.     

调质钢棒材组织性能预报软件的开发与应用

介绍了调质钢棒材组织性能预报软件的开发和应用情况,软件利用VB和ANSYS相结合,模拟了从轧制到调质整个工艺过程中的温度场、微观组织变化情况、组织性能、热处理效果等。温度场的计算中,实现了VB和ANSYS之间的相互调用,相变量化分析计算中充分考虑了影响CCT曲线位置的影响因素,并对CCT曲线进行解析化处理,有效提高了组织转变的预报精度。软件的实际应用表明,无论是热轧态还是调质态,组织性能的预报值均与现场实测值基本相符,这对提高调质钢产品质量的稳定性,改善产品的组织性能,提高产品合格率,具有重要的参考价值。     

一种微合金化马氏体不锈钢的连续冷却转变研究

用膨胀法结合金相与硬度分析研究了一种新型水轮机叶片用V、N微合金化CrNiMo不锈钢的连续冷却转变行为,获得了该钢的连续冷却转变(CCT)曲线及不同冷却条件下的显微组织和硬度。结果表明,试验用钢的1、3、和温度分别为580℃、730℃、295℃和190℃,其贝氏体和铁素体分别在冷速小于0.5和0.2℃/s时出现,冷速在0.056~0.5℃/s之间时,硬度随着冷速的增大迅速增加,尔后随着冷速的增大,硬度缓慢升高。     

变形和硼对低碳Mn-Nb钢连续冷却转变的影响

通过热模拟实验对不含硼和含硼低碳Mn-Nb钢在连续冷却过程中的相变进行研究,分别绘制了两种钢的连续冷却转变(CCT)曲线,并对不同冷却速度的试样进行组织观察和显微硬度分析.结果表明:变形使低碳Mn-Nb钢CCT曲线左移,提高开始转变温度,促进了多边形铁素体和珠光体的转变;微量硼的加入使低碳Mn-Nb钢CCT曲线右移,显著降低开始转变温度,明显抑制铁素体和珠光体转变,减小铁素体和珠光体存在的冷却速度范围,显著提高了低碳Mn-Nb钢的显微硬度.     

CCT控制冷却技术在线材生产中的应用

控制冷却技术是轧钢生产的关键技术,受到冶金界的高度重视。本文对控制轧制和控制冷却的概念、基础理论、分类及其在线材生产中的应用等情况进行了介绍。并阐述了湘钢大盘卷工艺设计中控制冷却的相关工艺流程,以及DANIELI、SMS先进的控轧控冷技术在湘钢大盘卷的应用状况。并对生产过程中控轧控冷技术关键和存在问题进行了分析讨论。     

Glass-forming ability,phase formation and mechanical properties of glass-forming Cu-Hf-Zr alloys

The influence of Hf additions on the glass-forming ability(GFA),phase formation and mechanical properties of Cu_(50)Hf_xZr_(50-x)(x=2,5,10,20 at.%)alloys has been systematically investigated.We report on a distinct correlation between phase formation and GFA of Cu_(50)Zr_(50)-based alloys.Increasing additions of Hf reduce the thermal stability of the high-temperature B2Cu(Hf,Zr)phase,while the thermal stability of the corresponding undercooled melt is enhanced.The GFA of these alloy series gradually raises up to 10 at.%Hf,whereas at 20 at.%Hf,the GFA is drastically lowered,since the B2Cu(Hf,Zr)phase becomes unstable and the precipitation of the lowtemperature equilibrium phases is favoured.This interrelation determines the microstructure and results in the formation of Cu-Hf-Zr-based bulk metallic glass composites.These composites not only show appreciable macroscopic plastic strain,but also high yield strength.