计算机模拟在焊接微观组织中的应用

介绍了计算机模拟在焊接热影响区（HAZ）微观组织模拟过程中应用的重要性，利用物理模拟方法建立了HAZ晶粒长大的模型，研究了铁素体不锈钢EB26-1（单相合金）焊接热影响区的晶粒长大过程，预测了HAZ中晶粒的分布，以及不同的热输入对HAZ晶粒长大的影响和HAZ中晶粒长大的热钉扎效应，指出了目前研究中存在的不足和今后的发展方向。     

9Ni钢焊接HAZ晶粒长大数值模拟

用Monte Carlo模拟方法研究了超低温用9Ni钢焊接热影响区(HAZ)的晶粒长大。结合焊接试验,建立了9Ni钢焊接HAZ晶粒长大模型,模拟了晶粒生长过程。模拟结果表明,HAZ奥氏体晶粒尺寸平均为70~85μm,与实际对应焊接工艺参数条件下的晶粒尺寸测量结果相吻合。并给出了HAZ存在很陡的温度梯度对晶粒长大起阻碍作用的"热钉扎"效应。研究了焊接工艺参数(焊接热输入和预热温度)对HAZ晶粒尺寸的影响,得出热输入是影响HAZ晶粒尺寸的主要因素。为获得优良的HAZ韧性,在焊接实际生产中需采用较小的热输入。     

超精细粒钢中焊接HAZ晶粒长大规律

根据传统金属学和焊接冶金学理论,对800 MPa和400 MPa两个强度级别的新一代钢铁材料进行了焊接热模拟试验,分析了焊接热影响区HAZ晶粒长大规律.结果表明,随着Tp和t8/5的逐渐增大,新一代钢铁材料焊接HAZ的奥氏体晶粒都存在严重的长大倾向,且400 MPa级较800 MPa级的HAZ奥氏体晶粒长大更为严重.     

TCS不锈钢复合热源焊接热影响区晶粒长大的预测

根据等温条件下的铁索体晶粒长大公式,推导出了焊接热影响区(HAZ)铁索体晶粒长大的动力学方程,并结合焊接热循环的数值分析结果对TCS不锈钢热影响区晶粒长大进行了预测.在此基础上,对复合焊新型焊接工艺条件下TCS不锈钢HAZ的晶粒长大情况进行了数值计算,得到了3种工艺参数下TCS不锈钢复合焊HAZ内的晶粒尺寸.基于TCS不锈钢复合焊接接头的金相图片,测量了HAZ内的平均晶粒尺寸,对数值模拟结果进行了验证.初步讨论了晶粒尺寸随热循环温度的长大情况和热循环温度差异对晶粒长大的影响规律.     

超细晶粒钢焊接HAZ晶粒长大规律分析

根据传统金属学和焊接冶金学理论，对800MPa和400MPa两个强度级别新一代钢铁材料进行焊接热模拟试验，分析了焊接HAZ晶粒长大规律。结果表明，随着峰值温度和‰的逐渐增大，新一代钢铁材料焊接HAZ的奥氏体晶粒都存在严重的长大倾向，且400MPa级比800MPa级的HAZ奥氏体晶粒长大更为严重。     

400MPa级新一代钢铁材料焊接热影响区晶粒长大图

新一代钢铁材料将是21世纪的主要结构材料，脉冲MAG焊是适合它的一种传统熔焊方法，为了促进400MPa新一代钢铁材料的焊接性研究及其工程应用，首先根据实测脉冲MAG焊的热循环曲线，确定了400MPa级新一代钢铁材料脉冲MAG焊的焊接热循环方程，并以此为基础建立了焊接HAZ的奥氏体晶粒长大方程和晶粒长大图，通过晶粒篚图，可以预测焊接HAZ各个部位的奥氏体晶粒篚的情况，研究结果表明，400MPa级新一代钢铁材料焊接热影响区的晶粒长大图的预测结果与其热模拟的实测数据吻合很好。     

焊接热影响区晶粒长大过程的微观组织模拟

利用蒙特卡罗方法(MC)结合焊接工艺试验，模拟了单相合金焊接热影响区(HAZ)的晶粒长大过程。文中首先应用试验方法确定了材料的晶粒长大动力学方程，在不同峰值温度和冷却速度等热输入的情况下，模拟结果再现了晶粒长大的动态过程，并体现出热钉扎效应。得出了与焊接实际过程相一致的模拟结果。为以后进行三维焊接热影响区晶粒长大模拟奠定了可靠的基础。     

蒙特卡罗方法及其在晶粒生长模拟中的研究进展

概述了蒙特卡罗（MC）模拟方法的基本原理及思想，介绍了当前蒙特卡罗模拟晶粒长大的主要方法和模型，综述了20年来国内外利用蒙特卡罗方法模拟晶粒长大过程，特别是焊接热影响区（HAZ）晶粒长大过程的研究进展，提出了目前研究中存在的问题及其今后发展的主要方向。     

400MPa级超细晶粒钢的焊接

对超细晶粒钢在焊接热循环作用下晶粒长大和组织、性能变化的规律进行了研究。400MPa级钢由于不存在第Ⅱ相粒子对晶粒长大的钉扎作用,晶粒长大趋势明显,焊接热输入越大,长大程度越严重。无论是焊接热模拟试件还是焊接接头硬度测试均表明HAZ不存在软化问题,接头拉伸试验断在远离热影响区的母材上。HAZ粗晶区有较多的侧板条铁素体,但制品冲击功未显示热影响区的冲机韧性低于母材,尽管试件断口分析说明粗晶区的韧性低于母材。     

焊接热输入对800MPa超级钢焊接接头组织性能的影响

对800 MPa超级钢不同焊接热输入作用下HAZ组织和性能进行了研究.结果表明,800 MPa超级钢在焊接热循环作用下HAZ晶粒明显长大,随着焊接热输入的增大,晶粒长大的趋势越显著;HAZ包含有超低碳贝氏体和细小铁素体等组织,过热区组织在焊接热循环的作用下变化明显,是断裂裂纹的发源地;不同焊接热输入下,整个HAZ的硬度...     

Numerical simulation of heat-affected zone microstructure in GMAW

The grain size in the heat-affected zone (HAZ) of workpieces is an important factor for evaluating the welding quality. The Monte Carlo technique of grain growth in the heat-affected zone of alloy is widely used. A finite element model (FEM) was employed to simulate the temperature field of gas metal arc welding (GMAW) ; the data of thermal cycles were used in the Monte Carlo model to calculate the grain sizes in different welding heat inputs. The equation for the relationship between Monte Carlo Step and real time has been estimated using regression analysis. Then mathematics model of the grain growth could be worked out by both the kinetic model and the Monte Carlo model. The dynamic process of grain growth was simulated by the result of the Monte Carlo model. The experimental result was used to prove the validity of this method in simulating of microstructure.     

工业纯铝焊接热影响区晶粒生长的模拟

结合焊接工艺试验和热模拟试验,运用蒙特卡罗(MC)技术模拟了工业纯铝L1060焊接热影响区(HAZ)晶粒生长过程。首先应用试验和统计学的方法确定了工业纯铝L1060晶粒生长的动力学模型,然后计算了焊接热循环,同时基于蒙特卡罗技术编制了模拟程序,最后在不同焊接热输入情况下,模拟了晶粒生长过程。模拟结果与试验结果非常接近,为评定焊接工艺和材料焊接性提供了依据。     

工业纯铝焊接热影响区微观组织模拟

将蒙特卡罗(MC)技术引入到晶粒生长模拟中，结合焊接工艺和热模拟试验，模拟了单相合金焊接热影响区(HAZ)晶粒生长过程。首先应用实验和统计学的方法确定了材料晶粒生长的动力学模型，然后计算了焊接热循环，同时基于蒙特卡罗技术编制了模拟程序。最后在不同焊接热输入情况下，模拟了晶粒生长过程。模拟结果动态演示了晶粒生长过程，并且体现了焊接热钉扎效应。模拟得出数据与试验结果非常接近，为评定焊接工艺和材料可焊性提供了依据。     

Three-dimensional Monte Carlo simulation of discontinuous grain growth in HAZ of stainless steel during GTAW process

The Monte Carlo (MC) simulations of grain growth in the heat affected zone (HAZ) of titanium alloys and ultra fine austenite steels are widely used. In single-phase alloys, the pinning effect of the grain boundary precipitates is one of the important factors to influence grain growth. However, it has not been considered in most of the simulations. In this study, both thermal pinning and precipitates pinning effects were taken into account to simulate grain growth in HAZ of austenite stainless steel SUS316 during gas tungsten arc welding (GTAW) process. By using heat transfer and fluid flow model, the thermal process of welding that influences grain structure evolution is obtained as well. The results of the simulation agree with the experiment and demonstrate that the grains in HAZ grow discontinuously when a large amount of carbides lie on the grain boundary.     

Analysis of grain growth in hybrid weld HAZ based on the coupled thermo-fluid mode

Accurate calculation of thermal cycles is a prerequisite to model grain growth in the heat-affected zone (HAZ). T improve the computation precision of thermal field and HAZ geometry, a coupled model of heat transfer and fluid flow is developed for laser + GMAW-P hybrid welding of TCS stainless steel. Utilizing computed temperature fields from the coupled model, the evolution of grain structure in the HAZ of TCS stainless steel in hybrid welding is numerically simulated by using a three dimensional Monte Carlo model. Simulation results show that more accurate HAZ grain structure can be obtained based on the coupled model of fluid flow and heat transfer, and the computed grain size distribution agrees well with the corresponding experimental results.     

Prediction of HAZ grain size in welding of ultra fine grained steel with different parameters

The temperature field and thermal cycling curve in the heat-affected zone during welding 400 MPa ultra fine grained steel by plasma arc were simulated using finite element method.The principle of grain growth kinetics was used to predict the grain size in the heat-affected zone under different welding parameters.The simulation results show that the growing tendency of HAZ grain could be controlled by adjusting the welding parameters,but the growth of HAZ grain could not be eliminated at all.The HAZ grain size became small with increasing of the cooling rate and added with increasing of welding current,arc voltage and welding speed.     

鞍钢ANS400超细晶粒钢焊接热影响区的冲击韧性

采用焊接热模拟及常规焊接工艺方法对鞍钢产400MPa级超细晶粒钢的焊接热影响区性能进行了研究。分析了在焊接热循环作用下ANS400超细晶粒钢的晶粒长大及组织性能的变化规律。