热历史对In-55wt%Sb亚共晶合金熔体粘度的影响

利用回转振动粘度仪在液相线以上较大温度范围内,测量了In-55%Sb（质量分数）亚共晶合金熔体在不同的升降温过程中的粘度.实验结果表明,熔体经历的热历史对其粘度具有显著的影响.熔体在降温过程中的粘度高于升温过程中,在过热100℃后的降温过程中熔体的粘度较之无过热的降温过程中要低.在不同的热过程中,粘度发生转折变化的温度不同,在升温过程中,发生在850℃左右,在过热100℃和无过热的降温过程中,分别发生在750℃和650℃左右.熔体粘度的突变反映了熔体结构在相应温度的突然变化.     

Effect of copper addition on the thermal contraction of indium melt clusters

The structure of In-1%Cu and In-5%Cu (mass fraction) alloy melts were studied at different temperatures above liquidus by using a high-temperature X-ray diffractometer and were compared with that of pure In melt. Experimental results show that with the addition of 1% Cu or 5% Cu, the thermal contraction phenomenon of atom clusters occurs in melts with the temperature increasing like pure In melt. With the addition of 1% Cu, the thermal contraction of atom clusters increases and the contraction is not homogeneous in the whole measurement temperature range. The sudden change and noticeable contraction can be found in the range of 280-390℃. The temperature range of the sudden change is lower than that of pure In melt. With the addition of 5% Cu, the thermal contraction of atom clusters decreases and the contraction is not consistent in the whole measurement temperature range. The anomalous change can be measured at about 600 ℃. At the same superheating temperature, the nearest interatomic distance r1 of     

Temperature-induced anomalous structural changes of Al-12wt.%Sn-4wt.%Si melt and its influence on as-cast structure

The temperature dependence of the viscosity of liquid Al-12wt.%Sn-4wt.%Si was studied with a high-temperature viscosity apparatus. Anomalous changes of viscosity of the melt were found at 1,103 K and 968K in the cooling process, which indicates anomalous structural changes of the melt. It is calculated that the anomalous structural change is associated with an abrupt decrease of atomic clusters' size and activation energy in the melt.According to the temperature of the anomalous structural changes, melt heat treatment process (quenching from superheat to pouring temperature)was performed on Al-12wt.%Sn-4wt.%Si melt prior to pouring, aimed to keep the small atomic clusters from higher temperature to lower pouring temperature. The results suggest that relatively small atomic clusters at the pouring temperature in the melt could generate a deep under-cooling of nucleation in the subsequent solidification process, and refine the as-cast structure. After being quenched from superheating to pouring temperature, the relatively small atomic clusters, especially the Si-Si clusters in the melt will grow to equilibrium state (relatively big atomic clusters) with holding time, resulting in the prominent coarsening of the Si morphology in the as-cast structure.     

玻璃净化剂组分对Cu50Ni50合金熔体过冷度稳定性的影响

在高真空下,研究了净化剂Ｂ２Ｏ３,８９％ＳｉＯ２＋１２．５％Ｂ２Ｏ３＋２．２％Ａｌ２Ｏ３＋０．６％ＣａＯ＋５．７％Ｎａ２Ｏ（简写为Ｎａ－Ｃａ－Ａｌ－Ｂ－Ｓｉ）和５０％Ｎａ－Ｃａ－Ａｌ－Ｂ－Ｓｉ＋５０％ｎａ２Ｂ８Ｏ４对Ｃｕ５０Ｎｉ５０ｘ合金溶体在循环过热过程中的过冷度及其稳定Ｃａ－Ａｌ－Ｂ－Ｓｉ玻璃的净化过程为物理－化学复合净化,但由于该净化剂粘度大,在循环过热的冷却过程中因发生合金溶体与净化剂分离     

冷却工艺对热轧V微合金化钢板组织性能的影响

本文通过热模拟试验, 分析了不同加热温度对V微合金化510 MPa级钢板原始奥氏体晶粒度的影响规律, 并通过工业试验分析了冷却工艺和奥氏体晶粒尺寸对钢板组织和性能的影响。试验结果表明: 当加热温度为1 230 ℃, 卷取温度一定时, 可以通过控制中间温度得到等轴铁素体或针状铁素体组织。当加热温度为1 160 ℃时, 随着终轧温度、中间温度和卷取温度的变化, 钢板组织和性能变化不明显。     

基于Abaqus的惯性轮热装仿真分析

根据热胀冷缩原理,给出热装间隙与孔件升高温度和轴件降低温度函数关系公式。依据热应力分析理论,以Abaqus软件为平台,通过有限元方法,研究了惯性轮轮心和轮轴间隙随温度变化情况。仿真结果表明,在轮轴温度场由20℃降至0℃,轮心温度场由20℃升至300℃,单边间隙量由-0.09mm变化至0.427mm,与理论值相吻合,为热装方法研究提供了参考。     

电加热快速热循环注塑模具热响应分析研究

研究了电加热快速热循环注塑工艺原理和模具结构,构建了电加热注塑模具的二维和三维热响应分析模型,分析获得了加热过程和冷却过程中模具型腔表面的热响应规律和温度分布规律,探讨了模具结构、加热元件和模具材料等因素对模具热响应效率和温度均匀性的影响。加热阶段,模具型腔表面的平均升温速率可达3．3℃／s,经过70S加热,模具表面可升高至250℃左右;冷却阶段,熔体的平均降温速率约为3．6℃／s。     

X80与X100管线钢粗晶区SHCCT曲线的比较研究

采用相变仪DIL805A/D将X80、X100管线钢空心微缩管状试样,以200℃/s加热至1 350℃,保温10 s后以1~200℃/s的不同速度冷却至室温,在分析显微组织、硬度和相变温度的基础上获得两种管线钢的粗晶区SHCCT曲线。对比发现,随着冷却速度的增加,X80与X100的相变温度均降低,而硬度都增加;在相同冷却速度下,X100的相变温度明显低于X80,硬度却更高。对于X100管线钢,当v10℃/s时,粗晶区为GB、QF和M-A组元的混合组织;当10℃/s≤v≤50℃/s时,组织由GB、BF和M-A组元组成;当v50℃/s时,出现LM组织,当v100℃/s后转变为LM和M-A组元的混合组织。而X80管线钢只有当v≥25℃/s时才出现BF,v100℃/s时开始出现LM组织。     

Viscosity of In and In-Sballoys

The dynamic viscosity of pure In, In-1%Sb (mass fraction, so as the follows) alloy, In-55%Sb hypoeutectic alloy and In-69.5%Sb eutectic alloy was measured by using a torsional oscillation viscometer at different temperatures above liq-uidus. The experimental results show that the viscosity of these melts decreases with increasing temperature. The anomalous change of viscosity occurs at about 430 and 470℃in pure In melt. The variation of viscosity with temperature well meets exponential correlation and no anomalous change occurs in measured temperature range in the In-1%Sb alloy melt. A transition occurs at about 800℃ in both of In-55%Sb and In-69.5%Sb alloy melts. The sudden change of viscosity suggests the structure change of melts. DSC (differential scanning calorimetry) curves of In-1%Sb alloy during heating and cooling were measured, and the results show that no structural variation in In-1%Sb alloy melt was testified further. In addition, the viscosity of In melt decreases with the addition of1%S     

不同降温速率下带焊缝304LN钢的热应力对比

为探究降温速率对304LN钢材作深冷处理时的热应力是否造成不良影响,采用带有焊缝接头的304LN钢试件标定母材区、焊缝区及热影响区,分别做2 ℃/min、5 ℃/min和直接液氮浸泡的降温处理,并用有限元相关理论验证测试结果的合理性。试验结果发现:随着温度降低,钢板上下表面各处感知温度不相同,且试件边缘温度较中心处温度低,但温差较小;在持续降温过程中,试件的热应力随着降温速率的增加而提高,热应力与温度曲线呈现出非线性关系。在降温速率为5 ℃/min时析出物更加均匀稳定。在一般深冷处理过程中运用前两种速率降温差异性较小,但在实际的力学性能测试和相关工艺中建议以5 ℃/min为准。     

回火态AerMet100钢的热物理性能

AerMet100钢是一种先进的二次硬化型Ni-Co-Cr系结构钢,通过试验获得了回火态AerMet100钢的密度、热应变、弹性模量、泊松比、热导率、流变应力随温度的变化情况,以及升温过程奥氏体转变Ac₁和Ac₃点,降温过程马氏体转变Ms点和马氏体转变系数K_m。最后基于获得的回火态AerMet100钢热物理性能数据,以齿轮淬火过程为例,采用SYSWELD有限元分析软件进行了仿真分析。结果表明,回火态AerMet100钢的室温组织为回火马氏体+残留奥氏体,在升温过程中奥氏体反应热焓为42 600 J/kg,其他热物理性能参数均在Ac₁~Ac₃范围内发生非线性变化,且测试状态和升温速度不同导致Ac₁和Ac₃存在差异,回火态AerMet100钢不同冷却速度下的Ms基本一致,约为213 ℃,马氏体转变系数K_m值为0.011 736。SYSWELD有限元仿真分析表明,试验获得的各项热物理性能数据可用于该钢的热处理模拟分析。     

大直径锻造耐磨钢球的热处理工艺

采用二次加热淬火和低温回火工艺改善?120 mm锻造耐磨钢球的使用性能,研究了二次加热淬火工艺中不同升温速率和淬火冷却时间对钢球硬度分布、冲击性能和显微组织的影响.得出钢球的最佳热处理工艺为:以2.8℃/min的速率升温至840℃并保温1 h,出炉空冷至800℃后淬入35℃水中冷却350～400 s,然后出水空冷至80...     

1 500 MPa级铝硅镀层热成形钢的试制及质量评价

为开发1 500 MPa级铝硅镀层热成形钢,采用连退模拟器模拟了 5种退火涂镀工艺,采用拉伸试验机、金相显微镜检测样板力学性能、金相组织及镀层组织,以确定最优退火、涂镀工艺;针对试验中的漏镀缺陷,分析了其产生原因.结果表明,在带钢运行速度为80 m/min,加热温度为770℃,快冷温度为650℃的工艺下,铝硅镀层CR1...     

熔体过热处理对Cu基块状非晶形成能力的影响及块状非晶的DSC研究

在水冷铜坩埚中采用铜模吸铸法制备出直径为3.0mm的Cu50Zr42Al8合金圆棒,研究了熔体过热处理对铜模吸铸法制备块状非晶合金的影响,表明通过熔体过热处理可以提高块状非晶的形成能力,并且存在一个最佳的过热温度。采用DSC技术对铜基成分为Cu50Zr42Al8块状非晶合金进行变温晶化动力学研究,结果表明,随着升温速率的增大,该合金的热稳定性参数和约化玻璃转变温度(Trg)均增大。     

OD1422 mm的X80级管线钢SH-CCT曲线测定与分析

采用Gleeble3500热-力学模拟试验机,对外径为φ1422 mm的X80管线钢焊接热影响区(HAZ)在不同冷却速度下的热循环过程进行了模拟,利用热膨胀法绘制模拟焊接热影响区连续冷却组织转变曲线(SH-CCT);结合光学显微组织和硬度测试等分析手段,研究了φ1422 mm的X80管线钢在不同冷却速度条件下焊接热影响区的组织变化规律。结果表明,冷却速度对X80管线钢的相变行为和微观结构具有显著影响。当冷却速度为1 ℃/s时,组织转变为贝氏体;当冷却速度达到7 ℃/s时,开始产生马氏体组织;当冷却速度为20 ℃/s时,组织内较高位错密度的板条贝氏体较多,组织晶粒较小。当冷却速度在7~20 ℃/s之间时,X80管线钢热影响区的显微硬度和冲击性能都大于母材。     

Microstructure and thermal expansion of copper-based amorphous alloys during structural relaxation

(Cu43Zr48Al9)98Y2 amorphous alloy bar was prepared by the arc melting copper mold absorption casting method,and then,the amorphous alloy was annealed at different temperatures for different times.The influence of heating rate on thermal expansion and thermal stability was studied by thermomechanical analysis(TMA),and the microstructure evolution of the amorphous alloy during structural relaxation and crystallization was studied by XRD and TEM.Results show that the structural evolution behavior of the(Cu43Zr48Al9)98Y2 amorphous alloy can be divided into five different stages(structural relaxation preparation stage,structural relaxation stage,first crystallization stage,second crystallization stage,and grain growth stage).When the heating rate is 20 K/min,the amorphous alloy has the smallest thermal expansion coefficient and the best thermal stability.The width of the supercooled liquid region is 66.42 K.Samples with different relaxation states were prepared by annealing at the heating rate of 20 K/min.The structural evolution of amorphous alloys with different relaxation states is as follows:amorphous→CuZr2+AlCu2Zr7→CuZr2+AlCu2Zr7+CuZr(B2)+CuZr(M)+Cu10Zr7→CuZr2+AlCu2Zr7+CuZr(B2)+CuZr(M).After annealing at 706 K and 726 K(in the supercooled liquid region)for 1.5 h,the amorphous-nanocrystalline composites were obtained.When the annealing temperature is 706 K,the crystallization process of the sample is as follows:amorphous→Cu10Zr7→Cu10Zr7+CuZr,and for the sample at 726 K,it is as follows:amorphous→CuZr2+AlCu2Zr7+Cu10Zr7→Cu10Zr7+CuZr2→CuZr2+CuZr(B2)+Cu10Zr7.     

500 MPa级门架型钢的奥氏体晶粒长大行为

为探究加热温度和保温时间对500 MPa级门架型钢奥氏体晶粒尺寸的影响,以两种不同成分试验钢为研究对象,采用了SK型管式加热炉分别将试验钢加热到1000~1200 ℃下保温15、30 min,快速冷却后对组织进行观察。结果表明,奥氏体晶粒尺寸随着加热温度的升高和保温时间的延长而长大,Cr元素的添加对奥氏体晶粒的长大具有一定的抑制作用,研究结果对制定大生产加热具有实际指导作用。     

快速加热和短时保温对22MnB5钢组织与性能的影响

将快速加热、短时间保温及快速冷却的快速热处理方法应用于钢的热成形工艺中,利用连续退火试验机对材料热处理过程进行模拟试验,研究不同工艺参数下22MnB5钢相变点的变化规律以及组织与性能的演变规律,并揭示其机理。结果表明,加热速率增大提高了相变点温度,加热温度需要大于950 ℃才能保证完全奥氏体化。传统热成形工艺最终组织为全马氏体结构,而快速热处理工艺为马氏体、贝氏体和未溶碳化物共同组成的组织,且晶粒尺寸从11.50 μm细化至7.60 μm。在1000 ℃保温10 s时力学性能表现较好,此时抗拉强度相较于传统热成形工艺略有提高,且伸长率从6.39%提高至8.44%,产生这种具有优异性能的组织构成的原因与快速加热和短时间保温导致的成分不均匀有关。     

大方坯含硫钢表面纵裂纹成因分析与控制

针对大方坯含硫钢表面纵裂纹问题,对裂纹缺陷进行了金相、能谱观察,发现纵裂纹在铸坯出结晶器后发生;通过高温热塑性测试和组织析出区间的确定,分析了硫加入对钢的高温热塑性和组织析出区间的影响,确认在900 ℃以下第三脆性区间,奥氏体晶界形成的先共析铁素体弱化了晶界强度,在热应力、组织应力、机械矫直应力的作用下发生晶界开裂是导致含硫钢表面纵裂纹的根本原因。在此基础上开展了保护渣优化、二冷区改造、铸坯加热和堆冷过程保温等工艺研究。研究结果表明,提高保护渣碱度、降低保护渣熔点和黏度、延长二冷区长度、规范加热和堆冷工艺,大方坯含硫钢铸坯表面纵裂纹得到了较好控制,因纵裂纹导致的圆钢钢质原因修磨率从20%降低到5%以下。     

工程机械用高强钢Q1100热处理参数及热物理性能预测

利用JMatPro 7.0软件模拟预测Q1100高强钢的平衡相组成、钢的连续加热奥氏体化(TTA)曲线和钢的过冷奥氏体连续冷却转变(CCT)曲线、淬透性以及热物理性能参数。计算结果表明:Q1100高强钢奥氏体化温度Ac₁=713.3 ℃,Ac₃=831.9 ℃。钢在连续加热过程中,加热速率在1000 ℃/s时,奥氏体均匀化时间最短。钢在连续冷却过程中,其屈服强度、抗拉强度和硬度均随冷却速度的增大而增大,当冷却速度为100 ℃/s时,硬度、屈服强度和抗拉强度分别达到其最大值41.7 HRC、1180 MPa和1267 MPa。热物理性能参数密度和杨氏模量均随温度的降低而增大,热导率则先减小后增大;比热容、泊松比和线膨胀系数均随温度的降低而减小。