共查询到17条相似文献,搜索用时 171 毫秒
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计算机模拟焊接热影响区晶粒生长的研究进展 总被引:6,自引:2,他引:6
概述了蒙特卡罗(MC)模拟方法的基本原理及特点,介绍了当前蒙特卡罗方法模拟焊接热影响区(HAZ)晶粒生长的主要模型,综述了国内外利用蒙特卡罗方法模拟晶粒生长过程特别是焊接热影响区(HAZ)晶粒生长过程的最新研究进展,提出了目前该领域研究中存在的主要问题及其今后发展的主要方向。 相似文献
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建立了等离子熔积快速直接成形(Plasma Deposition Manufacturing, PDM)过程多相混态场统一模型,基于蒙特卡罗法(Monte Carlo,MC)建立热影响区(Heat Affected Zone,HAZ)晶粒长大过程的数学模型。分析了不同热源功率工艺条件下熔池温度场和流场的变化规律以及特征点的温度循环曲线,进而探究了热源功率对热影响区晶粒尺寸与分布的作用机理。对AISI316合金等离子熔积过程进行了模拟,所得的计算结果与试验结果基本一致。 相似文献
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结合焊接接头的微观组织观察和宏观性能试验,分析了超细晶粒钢筋直流闪光对焊接头热影响区的显微组织、焊接热影响区各区段的显微硬度分布;利用蒙特卡罗模拟方法,模拟了400MPa超细晶粒钢在一定焊接规范下热影响区奥氏体晶粒的演变情况。结果表明:从熔合区到母材,随着距熔合区距离的增大,显微特性发生明显变化;显微硬度只在焊缝心部区域出现局部降低,但这并不影响整个接头的宏观性能。数值模拟可以预测HAZ中晶粒的分布及温度梯度对晶粒长大的阻碍作用.与实际晶粒大小较为吻会. 相似文献
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铸态42CrMo环坯热辗扩微观组织模拟 总被引:1,自引:0,他引:1
为避免传统环件热成形工艺需要多次加热等问题,以铸态42CrMo合金环坯短流程铸辗复合成形工艺为研究对象,通过Gleeble-1500D热模拟试验机及金相显微镜进行系列试验研究,得到温度850~1 150℃,应变速率0.05~5 s-1的流变应力曲线。对流变应力曲线进行图形变换求解出位错密度变化和每个动态再结晶晶粒生长的动力学行为,并评估成核和动态再结晶晶粒的生长动力学行为。研究晶粒拓扑变形技术,并通过主成分分析对晶粒的拓扑结构进行优化。结果表明,采用Kock-Mecking(KM)位错密度模型可以揭示42CrMo合金动态再结晶过程中的位错密度演变,结合元胞自动机和优化后的晶粒拓扑变形技术的KM位错密度模型,能精确地模拟位错密度动态再结晶过程。 相似文献
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运用ANSYS有限元分析软件,针对800 MPa超细晶粒钢建立了电弧焊焊接过程的有限元模型,利用该模型对不同焊接参数下的焊接热循环过程进行了模拟,并结合实际焊接试验进行了验证。结果表明:有限元模拟焊接接头的温度分布与相同焊接参数下实际焊接试验所测得的焊接接头的温度分布一致,证明了有限元模拟的正确性;当焊接热输入量超过845 J·mm-1时,冷却时间增速明显加快,焊接热影响区组织粗化严重。 相似文献
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针对铁素体不锈钢焊接HAZ晶粒易长大的问题,提出采用小热输入的CMT焊接工艺。通过分析接头HAZ的显微组织、显微硬度和冲击性能,探讨了4003铁素体不锈钢焊接接头HAZ组织和性能,并与常规MIG焊焊接接头试样的组织、性能进行对比。试验结果表明:采用CMT焊接工艺获得的接头HAZ粗晶区宽度为460μm,明显窄于MIG焊接接头的粗晶区宽度545μm;CMT接头强度与MIG焊接接头显微硬度值相近,但CMT接头HAZ冲击韧性较MIG焊接接头试样提高了16.28%。 相似文献
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Some investigations on microstructure and mechanical properties of submerged arc welded HSLA steel joints 总被引:1,自引:1,他引:0
Keshav Prasad D. K. Dwivedi 《The International Journal of Advanced Manufacturing Technology》2008,36(5-6):475-483
This paper investigates the influence of the submerged arc welding (SAW) process parameters (welding current and welding speed)
on the microstructure, hardness, and toughness of HSLA steel weld joints. Attempts have also been made to analyze the results
on the basis of the heat input. The SAW process was used for the welding of 16 mm thick HSLA steel plates. The weld joints
were prepared using comparatively high heat input (3.0 to 6.3 KJ/mm) by varying welding current (500–700 A) and welding speed
(200–300 mm/min). Results showed that the increase in heat input coarsens the grain structure both in the weld metal and heat
affected zone (HAZ). The hardness has been found to vary from the weld centre line to base metal and peak hardness was found
in the HAZ. The hardness of the weld metal was largely uniform. The hardness reduced with the increase in welding current
and reduction in welding speed (increasing heat input) while the toughness showed mixed trend. The increase in welding current
from 500 A to 600 A at a given welding speed (200 mm/min or 300 mm/min) increased toughness and further increase in welding
current up to 700 A lowered the toughness. Scanning electron microscopy of the fractured surfaces of impact test specimen
was carried out to study the fracture modes. Electron probe micro analysis (EPMA) was carried out to investigate the variation
in wt.% of different elements in the weld metal and HAZ. 相似文献
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采用双面双弧同步立焊工艺方法,对8 mm厚5083铝合金进行自熔试验,I形坡口一次熔透,焊缝成形美观。通过调节两侧电弧热量配比研究熔池成形规律,并从焊接接头的微观组织、力学性能分析其连接机理。研究结果表明,随着热输入的增加,双面双弧同步立焊热量加速集聚,熔深以三次幂函数的速度增大。双面双弧同步立焊接头轮廓呈“双曲线形”,而相同热输入下的单面焊接头则呈“倒马鞍形”。总热输入一定的情况下,双面双弧接头正面熔宽随能量配比系数的增大而增大,反面熔宽随能量配比系数的增大而减小,中间熔宽基本不变,熔化面积随能量配比系数的增大先增大后减小;能量配比系数一定时,随着焊速的增大,接头熔宽和熔化面积均减小。母材组织为条带状纤维织构,热影响区发生静态回复与再结晶,变形组织消失,产生新晶粒,焊缝区主要由α-Al固溶体、β相(Al8Mg5)质点和骨骼状的Mg2Si析出相组成。焊缝的抗拉强度随着能量配比系数的增大而减小,拉伸断裂形式为韧性断裂。热影响区出现软化现象,双弧交汇区硬度低于正面焊缝区。 相似文献
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《Measurement》2016
The prediction of temperature distribution is a critical process in the study of welding thermal field. Therefore, the accuracy in temperature measurement is quite important to provide meaningful results and to establish the coupling among thermal field results and other studies in welding as mechanical and microstructural analyses. This work deals with statistical analysis and design of experiments (DoE) in order to establish an optimal experimental design for thermal history measurements in welding processes with thermocouples independent of base material. Calculations from theoretical correlations and computational modeling of heat flow were used to accomplish the present study. The Gas Tungsten Arc Welding process (GTAW) was used in the experiments along with plates of a structural steel (ASTM A 36) and a martensitic stainless steel (AISI CrMo 12-1). Four different parameters were studied related with the disposition, separation, depth, thermocouple arrangement and application of thermal paste. An optimal design was able to measure the maximum temperatures in adjacent zones to the weld bead, which are important for the study of welding thermal behavior. 相似文献