中厚板高密度管层流无约束淬火与控冷的关键技术

介绍了中厚板高密度管层流无约束淬火与控冷的若干关键技术，其中包括流射沸腾冷却强化机理及其技术、无约束条件下板形平直度的系统控制技术、基于喷水强度分布的集管结构与参数优化设计、钢板瞬态温度场数值模拟与仿真、淬火机水循环系统的动态平衡技术等。这些技术已在国内多家中厚板淬火与控冷系统中成功获得应用。     

中厚板淬火过程中冷却变形影响因素分析

利用ANSYS三维热弹塑性有限元对中厚板淬火中的钢板变形进行热力数值模拟,并结合实验研究对钢板冷却变形影响因素进行分析,以量化方式研究了喷流形式(高压喷射流与常压管流)、上下喷嘴水比、纵向喷嘴分布间距(辊距)、钢板运行速度对钢板冷却变形的影响,为淬火过程获得平直板形提供理论基础.     

管流无约束淬火系统中上集管流量影响因素分析

在舞钢NAC快速冷却系统调试过程中,由于上下集管水比达不到工艺要求,对上集管U形管数目进行了调整,得到了满意的结果,同时对调整前后的数据进行分析,发现上集管数目减少后流量显著下降,针对这一现象应用有限元分析软件FLUENT对集管内流场进行了模拟计算,并分析了引起流量减少的原因。     

大规格高碳钢线材控冷工艺参数对力学性能影响的模拟研究

通过利用热模拟机Gleeble-1500对φ9mm高碳钢线材吐丝后控制冷却过程的模拟,研究了控冷工艺参数的变化对高碳钢线材力学性能的影响,得到了试验条件下最佳的控冷工艺制度,为实际生产提供了有价值的理论参考。     

中厚板淬火及控冷过程流量调控装置供水方式研究

利用计算流体动力学(CFD)和有限元数值模拟方法(FEM),对中厚板淬火及控冷过程流量调控装置供水方式进行了研究。对流量调控装置关键件—低位水箱进水方式、低位水箱形状、进水管有无阻尼孔等结构出水均匀性进行比较,得出方形水箱、水箱多路进水及进水管有阻尼孔情况下出水效果最理想的结论。     

控冷工艺参数对中厚板均匀冷却的影响

 确定了中厚板ACC冷却系统的换热边界条件,建立了钢板温度场有限元计算模型,利用现场实测数据对模型计算结果进行了验证,并且分析了不同冷却工艺参数包括集管开启方式、辊道速度以及冷却介质温度对钢板终冷温度、返红温度以及温差的影响规律,从而为实际生产中提高钢板控冷过程中的冷却均匀程度提供理论依据。     

控轧控冷工艺参数对Nb微合金化高碳钢组织的影响

在Gleeble-1500热／力模拟机上模拟了加热温度、变形温度和冷却速度对含Nb和不含Nb高碳钢组织的影响。试验结果表明，0．71％c钢含0．031％Nb时，原始奥氏体平均晶粒尺寸减少30μm左右，再加热粗化温度由1050℃提高至1175℃以上，变形奥氏体再结晶温度由800℃提高到900℃以上。     

中厚板淬火机集管流场的数值模拟与参数优化设计

对中厚板无约束淬火机集管流场进行了数值模拟,得到了管内流体的流动特性;建立了基于喷水强度目标函数的集管结构参数优化模型,取得了理想的设计效果.     

气垫炉批量生产LY12CZO薄淬火板工艺参数探讨

探讨阐述了,气垫炉生产线批量生产LY12CZO薄淬火板淬火工艺参数及板形控制技术,稳定了淬火板性能,减少了淬火变形,提高了成品率。     

淬火冷却速度对碳素钢显微组织的影响

在Gleeble2000热模拟实验机上对普通碳素钢Q235进行了不同温度的单道次变形实验，对变形后的试样采用三种不同的介质以不同冷却速度进行淬火，分别为水、-60℃的干冰酒精溶液和含50％NaCl的冰盐水。实验结果表明，不同冷却速度对淬火后的组织状态影响很大。在冰盐水中淬火，钢的淬透性较高，变形后原始奥氏体状态基本上得到保留。在干冰酒精中淬火钢的淬透性最差。     

辊底式钢板淬火加热炉的技术改造

通过对炉体结构的改造,解决了电加热元件易脱落及氧化皮清除困难的问题;采取红外线传感系统,提高了传动自动化程度;通过调整压头喷水口的尺寸,确保了钢板淬火质量。技术改造取得了良好的效果。     

淬火-配分马氏体钢的组织特征

淬火-配分(Quenching and Partitioning,简称QP)工艺是针对马氏体钢提出的热处理新工艺。利用QP工艺处理40Si2Ni2钢,并通过扫描电镜观察其微观组织特征。结果表明,与传统淬火+回火工艺得到的组织不同,QP组织为低碳(回火态)和高碳马氏体(淬火态)共存,其中高碳马氏体呈现为有规则几何形状、边界清晰、无析出物析出的块状组织,淬火温度(QT)对高碳马氏体(淬火态)量有影响。     

Martensite Transformation in Ni-Mn-Ga Ferromagnetic Shape-Memory Alloys

The crystal structure of Ni-Mn-Ga ferromagnetic shape-memory alloys is extremely sensitive to composition. Several martensitic structures including tetragonal (five-layered), orthorhombic (seven-layered), and nonmodulated tetragonal have been observed. Temperature-dependent X-ray diffraction measurements and calorimetry have revealed markedly different transformation behavior in the tetragonal and orthorhombic materials. The orthorhombic material shows a much larger difference between the martensite start and finish temperatures as compared to tetragonal martensite. The difference in transformation character can be explained from a thermodynamic standpoint by including the difference in the strain energy contribution for the two different martensite phases. This article is based on a presentation made in the symposium entitled “Phase Transformations in Magnetic Materials," which occurred during the TMS Annual Meeting, March 12–16, 2006, in San Antonio, Texas, under the auspices of the Joint TMS-MPMD and ASMI-MSCTS Phase Transformations Committee.     

Effects of Applied Stresses on Martensite Transformation in AISI4340 Steel

 This study aims at the experimental analysis of the transformation induced plasticity (TRIP) phenomenon. Experiments are conducted in which martensite is allowed to grow under the influence of a series of externally applied stresses. The magnitude of the applied stresses is less than 67% of the yield strength of austenite σγ(Ts). Since there is no obvious difference between the transformation plasticity under tension and the compression for the lower applied stresses, only compressive stresses are applied. The results confirm that the transformation plasticity is proportional to the applied stress if the latter does not exceed 67% of σγ(Ts). The TRIP strain, the kinetics, and their dependence on the applied stresses are studied. The comparison between calculated results and experimental results shows that the model accurately describes the phenomenon.     

Cu对304奥氏体不锈钢应变诱发马氏体相变的影响

借助 X-射线衍射分析法研究了 0.45% ~1.44%Cu 对(%)：0.068 ~ 0.072C 18.72~19.06Cr 、9.40~ 9.46Ni的304不锈钢-196 ℃低温拉伸应变诱发马氏体相变的影响。结果表明,Cu对304不锈钢-196 ℃应变诱 发e马氏体相变有明显的抑制作用;当Cu含量增至1.44%时,在经低温变形的钢中未检测到ε马氏体相变。随钢中Cu含量增加,-196℃ 应变诱发α'马氏体相变倾向降低,致使应变累积到一定程度后,流变应力低于低Cu钢。     

低温奥氏体钢相变的结构参数

研究了低温奥氏体钢中层错能和强度对相变的作用，导出了相变临界分切应力和层错能与强度之间的关系式，发现奥氏体相变结构参数对马氏体相变特性有很大影响。     

Effect of Prior Cold Work on the Martensite Transformation in SAE 52100

Numerous publications refer to the phase transformations and properties of SAE 52100 steel, and this paper concerns itself with the effect of prior cold deformation on the martensitic hardening response. TheA _c1 and A_c3 temperatures are lowered due to cold work as is theM _s with a resultant increase in the retained austenite content for a given hardening cycle. Significantly, the prior cold deformation results in a refinement of the austenite grain size. The low angle dislocation cells produced by the cold deformation recover during the heating to the austenitizing temperature to form fine ferrite subgrains. The intersections of the fine ferrite subgrains with the spheroidal carbides in the soft annealed microstructures are preferential sites for nucleation of austenite. This results in finer austėnite grains, which produces accelerated carbide dissolution and austenite alloy enrichment compared to un worked, soft annealed structures. The mechanism for the accelerated austenitization is significant in predicting heat treatment response from published phase transformation data for SAE 52100 steel.     

铁基合金马氏体相变宏观点阵变形的特征

利用原子力显微镜观察并定量分析了铁基合金4种典型惯习面马氏体相变的宏观点阵变形特征。结果表明：{3,10,15}f薄片马氏体和{2,5,9)f透镜马氏体的宏观点阵变形呈一次均匀切变特征,其宏观点阵变形完全符合“不变平面应变”特征;而{2,2,5}f片状马氏体和板条马氏体的宏观点阵变形特征不符合“不变平面应变”特征。     

Flexible Bamboo-Structured NiCoMnIn Microfibers with Magnetic-Field-Induced Reverse Martensite Transformation

The bamboo-structured Ni₄₅Co₅Mn_36.8In_13.2 fibers with martensitic transition temperature at room temperature were fabricated by melt spinning followed by annealing. A magnetic-field-induced reverse martensitic transformation from martensite to austenite with a shift of transformation temperature of 2.6 K/T was obtained in the microfibers. Different from the intrinsic brittleness evidenced in bulk alloy, the microfibers stored at 320 K (47 °C) were easily flexible, which is due to the fact that the formation of bamboo structures reduces the mismatch stress/strain near grain boundaries.