Finite-element simulation of induction heat treatment

An efficient finite-element procedure has been developed for the analysis of induction heat treatment problems involving nonisothermal phase changes. The finite-element procedure first simulates the magnetic field developed when currents flow through an induction coil by solving Maxwell’s electromagnetic field equations; at the following step, it calculates the temperature distribution in the workpiece due to eddy currents induced by the magnetic field. The final stage of the simulation involves the determination of the distributions of residual stress, hardness, and microstructure in the workpiece. The finite-element analysis includes temperature-dependent material properties, changes in permeability of the workpiece at the Curie temperature, a mixed hardening rule to describe the material constitutive model, and the incorporation of time-temperature-transformation (TTT) diagram. The procedure was applied to the simulation of the induction hardening of 1080 steel bar. Firstly, the magnetic field and temperatures developed in the workpiece during (a) the induction heating of an infinitely long 1080 steel cylinder by a single encircling coil and (b) the induction heating of a semi-infinite half-space by a single coil suspended above it were calculated using the finite-element procedures. These were validated by comparing them with analytical solutions derived for these configurations using a Green’s function method. Finally, to demonstrate the predictive capability and practical applicability of the current finite-element procedure, two examples pertaining to the induction heat treatment of an infinite 1080 steel bar of square cross section and a notched finite 1080 steel cylinder of circular cross section were analyzed to predict the magnetic field, temperature, and residual stress distributions. The current finite-element procedure could be used as a powerful design tool for linking induction heat treating parameters with the mechanical property attributes of the heat treated component.     

FEM modeling of induction hardening processes in steel

A modeling system for analyzing the integrated induction hardening processes was developed based on a general-purpose finite element program, with the capability to analyze the whole process from electromagnetic-induced thermal heating to final hardening. A coupled electromagnetic-thermal model was applied to study the induction heating process, which includes consideration of nonlinear material characteristics on temperature. Also, arrangement of AC current density distribution was conducted to simulate practical induction coil structure and magnetic concentrator effects to achieve desired heating patterns for later quenching and hardening analysis. Quenching analysis can provide cooling curve at any location in a heat-treated workpiece based on heat transfer principles. In hardening analysis, phase transformation was studied and an algorithm was developed to determine volumetric content of micro-structural constituents formed from austenitized phase in quenching process, based on analysis of the interaction between cooling curve and material time-temperature-transformation (TTT) diagram. Finally, hardness value was converted from martensite content based on a developed formulation. Validation was preliminary conducted based on comparison of hardening pattern of induction hardening of an automotive spindle with complex surface.     

基于ANSYS的多点式中频感应淬火温度场有限元模拟

研究了用多个淬火感应器对半径较大的回转体表面进行中频感应淬火的作用机理,针对较大半径的回转体表面的多点式感应淬火工艺进行参数设计,建立了多点式感应淬火过程的电磁场和温度场的非线性偏微分方程组。利用有限元分析ANSYS软件来模拟多点式中频感应加热过程,其中对激励电流用表格法加载来近似地替代实际旋转工件周期性的感应淬火,从而得到了工件温度场随时间的变化规律以及最终工件的温度场分布。结果表明,多点式中频感应淬火改善了较大半径的回转体的凹槽表面淬火过程,可以达到对感应淬火工件淬硬层的要求,解决了由于不同时感应淬火所导致的软带问题。     

Management of materials properties in an electro-thermo-metallurgical simulation of quenching following inductive surface heating

A numerical model for simulating quenching following inductive surface heating is proposed. The metallurgical model, which is based on the superposition principle and uses isothermal data, is integrated within a computerized code for heat exchanges (Flux2D) in order to simulate the thermal kinetics at any point on a test piece. The profile of the zones transformed during a rapid cycle can then be computed. This has been made possible by constructing a coupling scheme that considers the interaction effects among heat transfer, magnetic, and metallurgical phenomena. The coupling is based on a new approach that involves separating the physical laws into equation form to describe the physical phenomena and properties of the material. The latter has been investigated in depth in order to manage the properties in a more representative manner by considering the effect of phase transformations on changes in these properties. An illustrative example compares a coupled thermo- metallurgical numerical simulation with experimental results for treated cylindrical test pieces.     

双回路线圈连续移动感应加热的数值分析

采用有限元数值计算方法,以带导磁体的双回路线圈为热源,建立电磁场与温度场双向耦合的连续移动感应加热模型,研究模具整形面和刃口在双回路线圈感应加热时的温度分布。结果表明,使用双回路线圈连续移动感应淬火可以得到稳定的模具淬火温度;模具整形面淬火时,集肤深度内热量主要来自感应涡流产生的焦耳热,温升曲线表现为带预热的双峰曲线,集肤深度外热量主要来自高温区的热传导,温升曲线表现为单峰曲线;模具刃口淬火时,有比较明显的尖角效应,温升曲线表现为单峰曲线。     

30CrMnSiNi2A钢轴类零件感应热处理的数值模拟

利用Comsol软件对30CrMnSiNi2A钢的感应回火进行了模拟,利用控制变量法研究了感应加热过程中电源频率、电流以及线圈的结构和尺寸参数对工件内部温度均匀性的影响。结果表明,电流强度和电源频率越大,工件在感应加热过程中的升温速率越大,最终平衡温度越高,但其径向/轴向温差越大。线圈的匝数越多,工件的升温速率和径向/轴向温差越大,最终平衡温度越高。线圈半径的变化仅会对工件端部的升温速率产生影响,线圈半径越小,工件端部的升温速率越快,轴向温差越小。线圈截面外径和壁厚的变化对工件感应加热过程中的温度场没有影响。根据模拟结果的对比分析,提出了一种采用分段加热法与增设导磁体相结合的方法,对感应回火系统进行了优化。通过优化设计可使工件在感应加热过程中的径向温差基本消除,使轴向温差小于10℃。     

防止零件表面尖角部位感应淬火开裂方法

为了防止零件表面尖角部位在感应淬火过程中发生开裂,设计了一种装置,可以将零件表面尖角部位完全遮盖。该装置同时可以避免因感应器与零件接触而造成短路,从而避免零件被电流击伤。结果表明：使用该防开裂装置及方法,不仅可以有效避免零件表面尖角部位在感应淬火过程中发生开裂,而且可以避免零件被电流击伤。     

Numerical and experimental analysis of 3D spot induction hardening of AISI 1045 steel

In order to analyze and predict the material property of AISI 1045 steel during spot induction hardening (SIH), a 3D electro-magnetic model coupled temperature fields with time-dependent boundary conditions was developed using finite element simulation software ANSYS. A magnetizer mounted at single-turn copper coil inductor, the calculation of the material hardness and the prediction of phase transformation were taken into account in this model via defined material laws. The phenomenology model in this work presented a novel and simplified way to predict the temperature, the hardness and phase transformation in SIH process. In situ temperature and current measurement as well as hardness and microstructure analyses were carried out to verify this model.     

50AT尖轨感应淬火的数值模拟

通过对尖轨轨头进行中频感应淬火处理,可提高其强度、耐磨性及延长尖轨寿命。轨头淬火后,会产生较大的残余应力。通过建立50AT尖轨模型,进行淬火模拟仿真得到淬火后残余应力分布,并采用盲孔测应力法对比验证应力结果。结果表明:轨底中部残余应力值较大,尖端部分残余应力值较小;选择轨底相同位置测点,得到模拟仿真应力值与实测应力相差较小。试验结果可用于指导尖轨淬火后残余应力的消除及振动时效时激振器的放置位置。     

Development and application of computer simulation code COSMAP on induction heat treatment process

Abstract

Induction heating reduces energy consumption, contributes to the protection of the environment, and improves productivity. This paper describes the development and application of computer simulation of induction heat treatment considered with coupling of temperature field and magnetic field. In this paper, the developed simulation code COSMAP is introduced as a CAE software system for considering the design of induction heat treatment process. It covers all aspects of heat treatment simulation, from magnetic and electrical to thermal states, phase transformation, residual stresses including as well all metallurgical phenomena.     

调心滚子轴承感应淬火工艺与组织性能的数值模拟

基于电磁场-温度场-组织场-应力应变场耦合模型,利用DEFORM软件模拟双列调心滚子轴承内圈感应淬火过程,并提出分段电流密度的淬火工艺,研究了轴承内圈感应淬火过程中温度变化、组织演变以及表层与次表层硬度、残余应力和残留奥氏体等。结果表明:分段电流密度的感应淬火方法能够使轴承内圈淬硬层均匀分布;加热效率随线圈电流密度增加而增大,且尖角位置温度会出现突变;淬火后滚道表面残留奥氏体含量约为6.97%,马氏体含量约为92.3%,表面硬度约为60.9 HRC,滚道淬硬层约为2.97 mm;深冷处理后残留奥氏体含量与残余应力降低,马氏体含量与硬度均提高;残余应力沿内圈中心径向平面对称分布,且次表层残余应力最大;数值模拟结果与试验具有一致性。     

半固态触变成形二次加热数值模拟及参数优化

半固态触变成形技术以其节省能源、成形力小和近终成形等优点受到广泛关注。通过对ZL101铝合金试样在各种不同工艺参数下的感应加热温度及温度均匀性进行的研究，运用CAE技术模拟加热频率、加热时间、线圈电流强度、线圈尺寸、加热后停留时间等参数对坯料温度场的影响，提出二次加热中获得均匀温度场的工艺条件、参数与措施。模拟结果与感应加热的实测数据具有很好的吻合性。     

齿轮单频及同步双频感应淬火工艺的比较研究

根据各类齿轮不同齿轮模数、形状及其淬硬层深度、硬度、显微组织,热处理畸变要求的应用范围,比较高频、中频感应淬火、双频、SDF 同步双频感应淬火工艺的优缺点及其应用范围。     

基于PLC与HMI的感应淬火机床控制系统的设计

针对回转支承整体淬火机床功能单一、控制系统开放性差、难以实现数据管理等问题,设计了以PLC为控制核心、HMI触摸屏为人机交互界面的淬火机床全自动控制系统。实现了整体淬火工序的时序与逻辑控制;通过触摸屏监测加工的动态过程,可对零件加工参数进行实时存取操作;系统中功率和淬冷时间等关键参数可依据用户的工艺需求设定,不仅解决了数据管理和系统开放性不足的问题,还提高了淬火效率和淬火稳定性,实现了整体淬火的自动化控制。     

基于ANSYS模拟预测S45C钢轴感应加热工艺参数

基于ANSYS有限元法对感应加热过程中电磁场和温度场进行了耦合分析,通过模拟得到了感应加热过程中频率f、电流密度Js和加热时间t等重要工艺参数之间的关系曲线,制定了预测工艺参数的确定方法。针对S45C钢轴类工件的技术性能要求提出了试制工艺参数,进行了感应淬火试验及相应的ANSYS有限元模拟,结果表明轴径向的温度模拟结果与硬度梯度曲线试验结果存在一致性。     

Thermoelastoplastic and Residual Stress Analysis during Induction Hardening of Steel

A theoretical model was developed to predict the thermoelastoplastic and residual stresses developed in a round steel bar during induction hardening. For numerical analysis, a quasi- static, uncoupled thermoelastoplastic solution based on the hyperbolic sine law of Tien and Richmond was formulated. The properties of the material were assumed to be temperature dependent. The phase transformation was considered in the numerical calculation, and the results were compared with the case where phase transformation is avoided. The cylinder was heated rapidly; once the temperature of the outer surface exceeded the transformation temperature, the cylinder was rapidly cooled. Accordingly, in the numerical calculation, only the area at the vicinity of the outer surface was assumed to transform to martensite. The results showed that the compressive residual stresses at the vicinity of the outer surface were considerably higher than the tensile stresses at the center.     

台阶轴连续感应淬火组织硬度分布预测及其工艺优化

建立了S45C钢台阶轴连续感应淬火过程的分区模拟模型,加载相应的物性和工艺参数,采用感应加热结束时刻轴径向温度分布、Maynier模型、Carsi修正模型和钢CCT曲线拟合预测其淬硬层深度分布,通过联动分析各方法的模拟结果优化了连续感应淬火工艺参数。结果表明,感应淬硬层中关键点b的100%、50%和0%马氏体的模拟深度分别为1.31、1.49和2.97 mm,误差分别为-12.67%、-13.87%和-1.00%,关键点e分别为1.44、2.02、2.54 mm,误差分别为-4.00%、-3.38%和-18.06%,与试验结果较吻合。通过感应淬火工艺参数改变和物理模型调整等探讨了零件各点处的轴径淬硬层变化,给出拟优化的感应淬火工艺参数。初步探讨了换热系数h变化对感应淬硬层的影响。     

凸轮轴超音频淬火工艺的改进

一种摩托车发动机用凸轮轴,材料为QT600-3球墨铸铁,要求其工作面具有足够的硬度和耐磨性。采用局部超音频感应淬火能达到凸轮轴的性能要求,但凸轮部位易过热、烧熔或开裂。改进淬火操作方法后,这些问题得到了解决。     

An analysis of induction hardening of ferritic ductile iron

Achievements of the induction hardening of ferritic ductile iron were investigated. Ductile iron is not advisable for use in induction hardening because of the small carbon content in the metal matrix of ferritic ductile iron. The carbon content in the metal matrix of ductile iron can be increased by additional preparation of metal matrix before final induction heat hardening. Wear resistance of the induction hardened ferritic ductile iron can increase as result of increased carbon content of the metal matrix and higher hardness after induction hardening. Some heat pretreatments for metal matrix preparation were applied before the induction hardening of ferritic ductile iron. The process parameters of the induction hardening heat pretreatment were analyzed and optimized. According to recommended elemental composition of ferritic ductile iron and required mechanical properties, the process parameters of the investigated induction heat pretreatment were optimized. The efficiency of pretreatment processes of induction hardening was analyzed. Applicability and manufacture ability of engineering components by proposed heat pretreatments were investigated. The limitations of the investigated heat pretreatment applications were estimated by the comparison of mechanical properties of heat-treated specimens.     

装载机铲刃板中频感应淬火工艺

介绍了装载机铲刃板中频淬火工艺的开发、生产线的组成以及淬火变形的控制措施。同时介绍了针对新工艺所进行的材料选用以及应用新工艺所取得的效果