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S. X. Wang D. S. Zheng Y. L. Liu ) Department of Material Engineering Luoyang Institute of Technology Luoyang China ) Luoyang Copper 《金属学报(英文版)》2000,13(2):629-632
1.IntroductionItisessentialtocalculatetemperaturefieldinmaterialscienceandtechnology.UPtonowsagreatnumberofstudies[1--3]havebeendone.However,therearesomeproblemsneedtobeclarifiedfurther.Thefirstofthemishowtodescribetheequationofheatconductionwhenthermalcoefficientisdependentoftemperature.Usually,inonedimension,itcanbeexpressedbybut,itisverydifficulttosolve.Anotherproblemishowtodealwiththelatentheatofphasetransformation.Thethirdandgreatestofthemishowtoimprovethecalculatingaccuracytthatis,howt… 相似文献
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Y.J. Li J.S. Pan M.J. Hu D. Tian W.M. Zhang Open Laboratory of the Educational Ministry for High Temperature Materials & Tests Shanghai Jiao Tong University Shanghai China 《金属学报(英文版)》2000,13(2):687-691
1.IntroductionThecomputersimulationofquenchinghasbeenvaluedincreasinglyandputintoindustrialappllcationll--4].Inordertomakesimulationbemoreclosetothepracticalsituationandenlargeitsindustrialapplications,thefollowingthreeproblemsneedtobesolved:1)theshapecomplexityoftheworkpiece;2)thecouplingofmulti-field;3)thehighdegreeofnonlinear[2--6].Atpresent,FEMhasbeengenerallyadoptedonthecomputersimulationofquenching.Withtheextensiveutilizationofthelarge-scalecommercialFEMsoftware,itisatrendthattheprogr… 相似文献
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将超细颗粒焊剂约束电弧超窄间隙焊接用于1Cr18Ni9Ti奥氏体不锈钢,通过改变焊接速度、电弧电压、焊接电流对焊缝成形进行了研究.结果表明,在热输入为1.75 kJ/mm和深宽比为1.34的条件下,也不易形成"梨形"焊道裂纹,并且单道焊接时熔化焊丝在超窄间隙内的填充高度可达11.5 mm.在其它焊接参数确定的情况下,随着电弧电压的增加,1Cr18Ni9Ti奥氏体不锈钢超窄间隙焊缝依次呈"凸焊缝"、"凹焊缝"及"电弧攀升"的成形规律.适合于超细颗粒焊剂约束电弧超窄间隙焊接1Cr18Ni9Ti奥氏体不锈钢的电弧电压与焊接电流匹配范围分别约为26~32 V和200~320 A. 相似文献
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基于ANSYS的管线钢堆焊温度场数值模拟 总被引:3,自引:0,他引:3
针对管线钢堆焊,考虑了材料热物理性能参数与温度的非线性关系,建立了焊接过程的数学模型和物理模型。利用ANSYS软件的APDL语言编写程序,实现了在移动热源载荷下的焊接有限元计算,分析对比了不同焊接工艺参数对焊接温度场的影响程度,并拟合出了焊接板厚与T8/5的经验公式。 相似文献
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Heming Cheng Xieqing Huang Jiang Fan Honggang Wang 《Metals and Materials International》1999,5(5):445-450
The calculation of a temperature field has a great influence upon the analysis of thermal stresses and stains during quenching.
In this paper, a 42CrMo steel cylinder was used an example for investigation. From the TTT diagram of the 42CrMo steel, the
CCT diagram was simulated by mathematical transformation, and the volume fraction of phase constituents was calculated. The
thermal physical properties were treated as functions of temperature and the volume fraction of phase constituents. The rational
approximation was applied to the finite element method. The temperature field with phase transformation and non-linear surface
heat-transfer coefficients was calculated using this technique, which can effectively avoid oscillationin the numerical solution
for a small time step. The experimental results of the temperature field calculation coincide with the numerical solutions. 相似文献
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针对管线钢焊接,考虑了材料热物理性能参数、相变潜热与温度的非线性关系,建立了焊接过程的数学模型和物理模型。利用ANSYS软件的APDL语言编写程序,实现了在移动热源载荷下的焊接有限元计算,分析对比了不同焊接工艺参数对焊接温度场的影响程度。 相似文献
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本文研究了ZrO2, Si3N4 和SiC三种陶瓷配副对1Cr18Ni9Ti不锈钢在90%的H2O2溶液中摩擦学性能的影响。结果表明,1Cr18Ni9Ti不锈钢在该环境下的摩擦学性能受配副的影响明显。 与ZrO2对磨,发生了粘着行为,导致了大的摩擦系数(0.17~0.27)和最高的1Cr18Ni9Ti不锈钢磨损量。与SiC对磨,发生了氧化和水解反应,形成的胶体膜起到了润滑作用,导致了小的摩擦系数(0.035)和最低的1Cr18Ni9Ti不锈钢磨损量。粘着行为和水解反应均发生于1Cr18Ni9Ti/Si3N4的磨损过程中,粘着与保护膜的耦合,导致了复杂的摩擦系数。对于配副,ZrO2的磨损体积最大,SiC次之,Si3N4表面有粘着层,因此磨损体积最小。 相似文献
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Sheila EdalatpourAhmad Saboonchi Saeid Hassanpour 《Journal of Materials Processing Technology》2011,211(11):1776-1782
The cooling of hot-rolled strips is of great importance due to its effects on the mechanical and metallurgical properties of the final product. In this paper, the effect of phase transformation on accurate prediction of strip temperature at the run-out table is investigated. For this purpose, a model is developed for the heat transfer and phase transformation in hot-rolled strips during the cooling process. The model is capable of calculating strip temperature and the volume fraction of steel phases during cooling at the run-out table under the two different situations of “regarding phase transformation latent heat” (RPTLH) and “disregarding phase transformation latent heat” (DPTLH). Actual data from a hot rolling line were used to evaluate the accuracy of the model. The model was used to predict strip temperature under the above two scenarios. Comparison of actual and predicted values in the two DPTLH and RPTLH cases revealed that disregarding the released heat would lead to considerable errors in temperature predictions. The results for different steel grades predicted by the model also showed that the higher the carbon content of the steel, the higher the error due to disregarding phase transformation latent heat. 相似文献
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通过钨极氩弧焊方法,对1Cr18Ni9Ti与2Cr13钢实施焊接,并对焊接接头整体进行焊后热处理。采用OM、SEM对2Cr13与1Cr18Ni9Ti钢热处理前后的焊接接头组织进行分析,利用显微硬度计、电子万能拉伸机测量了焊接接头的力学性能。结果表明,1Cr18Ni9Ti和2Cr13钢焊接接头热处理前焊缝组织为典型的柱状晶,组织为板条马氏体+残留奥氏体+碳化物;热处理后焊缝组织为回火索氏体,而且碳化物析出量也明显增多。拉伸时,热处理前后焊接接头断裂的部位都发生在奥氏体不锈钢热影响区一侧,热处理前后焊接接头的抗拉强度分别约为635.56、649.44 MPa;焊缝区的显微硬度分别约为276、222 HV0.5,热处理后焊接接头的整体显微硬度比热处理前的明显降低。 相似文献
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折弯模镶条淬火冷却时温度的瞬态分布特性对于研究6CrW2Si钢淬后变形机理有重要作用。考虑热物性参数、对流换热等因素随温度变化的影响,推导相变潜热转换为等效比热的定量解析并写入程序,建立了淬火过程三维温度场的非线性瞬态数学模型。通过金相观察、XRD物相分析和显微硬度测试方法对6CrW2Si钢镶条组织成分进行了试验研究。结果表明:表面换热边界条件和热传导两因素在不同时刻对零件的冷却速度交替起主导作用;65 s左右时马氏体转变所释放的潜热使得冷却速度有较大幅度降低,心部较表面所受影响大;冷却过程中镶条横截面的温度场由两表面交接处至心部呈梯度分布;零件只发生马氏体转变,且被淬透,最终得到的组织为马氏体+残留奥氏体+碳化物。 相似文献
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Hou Guoliang Zhou Huidi An Yulong Liu Guang Chen Jianmin Chen Jie State 《稀有金属材料与工程》2012,(Z1):388-393
WC-(W,Cr)2C-Ni coating was prepared on 1Cr18Ni9Ti stainless steel and C-276 Ni-base Hastelloy by high velocity oxy-fuel(HVOF)spraying.The effect of post heat treatment in air atmosphere on the microstructure,phase composition,microhardness,fracture toughness,and wear resistance of HVOF-sprayed WC-(W,Cr)2C-Ni coating was investigated.The microstructure and phase composition of the coatings were analyzed by means of field emission scanning electron microscopy(FESEM)and X-ray diffraction(XRD).The microhardness and fracture toughness of the coatings were measured using a microhardness tester and a Vickers hardness tester.Moreover,dry friction and wear behavior of the coatings sliding against Si3N4 ball was investigated using an oscillating friction and wear tester;and the worn surfaces of the coatings were analyzed by means of scanning electron microscopy(SEM).It was found that heat treatment within 500-800°C resulted in crystallization of amorphous phase in as-sprayed coating,generating nanoscale new phases such as NiWO4,CrWO4 and Cr2WO6.Besides,heat treatment led to increase of the microhardness of as-sprayed coating,and the highest microhardness was obtained after heat treatment at 800°C.The fracture toughness and wear resistance of the as-sprayed coating increased with increasing heat treatment temperature up to 700°C but tended to decrease with further elevating temperature.In other words,the mechanical properties and wear resistance of the as-sprayed coatings were worsened owing to excessive growth of oxidation grains and depletion of ductile Ni binder after heat treatment above 700°C.Thus it was suggested that as-sprayed ceramic composite coating should be post heat treated in air at a moderate temperature of 700°C so as to achieve the optimized mechanical properties and wear resistance. 相似文献
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The crystallization process of as-deposited Ti–Ni–(10.8–29.5)Zr amorphous thin films was investigated. The Ti–Ni–Zr as-deposited films with a low Zr content exhibited a single exothermic peak due to the crystallization of (Ti,Zr)Ni with a B2 structure. In contrast, a two-step crystallization process was observed in the Ti–Ni–Zr thin films with a high Zr content. Shape memory behavior of Ti–Ni–Zr thin films heat treated at 873–1073 K was investigated by thermal cycling tests under various stresses. The martensitic transformation start temperature increased with increasing Zr content until reaching the maximum value, then decreased with further increasing Zr content. The inverse dependence of transformation temperature on Zr content in the thin films with a high Zr content is due to the formation of a NiZr phase during the crystallization heat treatment. The formation of the NiZr phase increased the critical stress for slip but decreased the recovery strain. 相似文献
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以低熔点合金Sn和Zn为原料,制备了Sn-Zn合金,采用XRD,DSC和激光热常数测试仪对产物结构和热物理性能进行了表征。结果表明,Sn-9Zn合金相变温度为198.1℃,相变潜热为65.8J/g,热导率为53.4W/(m.K)。随着热循环次数的增加,合金相变温度略有升高,相变潜热和热导率逐渐降低。经500次热循环后,Sn-9Zn合金的相变温度、相变潜热和热导率变化均在5%以内。 相似文献