摘要
采用层流等离子体束对钢轨钢进行表面淬火可提高其服役寿命,但目前处理参数的选取只能依靠实验方法,费时费力,若能建立表面淬火过程仿真模型,快速预测表面淬火过程温度场变化及淬火后硬化区的硬度分布,可实现最优处理参数的快速选取。作者基于有限元方法建立了层流等离子体束表面淬火过程的温度场仿真模型,通过表面淬火实验所得硬度分布确定碳扩散极限值;借助JMATPRO确定各升温速率下奥氏体转变速率,建立了金相组织预测模型。温度场仿真模型能够计算表面淬火过程中温度场分布变化,通过选取大于相变温度(如U75V钢轨钢为745℃)的节点可预测硬化区的宽度与深度,仿真得到的宽度、深度与实验所得宽度、深度误差在8%以内;通过提取硬化区中节点的温度变化曲线,代入金相组织预测模型可计算硬化区各节点位置处的奥氏体和马氏体转变情况,并预测硬化区截面硬度值;通过改变层流等离子体束表面淬火处理参数(包括电弧电流、阳极口径、扫描速度等)进行表面淬火实验,发现仿真模型得到的硬度值与实际硬度值有很好的吻合性,验证了所提钢轨钢层流等离子体束表面淬火过程仿真模型的正确性。
Surface quenching of the rail steel using the laminar plasma jet can increase its service life,but the treatment parameters can only be determined by the experimental methods currently,which is time-consuming and laborious.If a simulation model for the surface quenching process can be established to quickly predict the variation of the temperature field in the surface quenching process and the hardness distribution within the hardened zone,the optimal treatment parameters can then be obtained rapidly.A numerical simulation model was firstly established by the finite element method to obtain the temperature distribution.Then the limit value of the carbon diffusion was determined by the hardness distribution obtained from the surface quenching experiment.After that,the Austenite transformation rate at each heating rate was determined using JMATPRO.Finally,a model for predicting the metallographic structure was proposed.With the numerical simulation model,the variation of the temperature field during the surface quenching process could be obtained.By selecting the nodes greater than the phase transition temperature(for example,745℃for the U75 V rail steel),the width and depth of the hardened zone could be predicted.The prediction error was found to be within 8%errors compared with experimental results.By extracting the temperature change curve of the nodes in the hardening zone and substituting into the metallographic structure prediction model,the transformation of the austenite and martensite at each node position in the hardening zone could be calculated,and the hardness at the hardening zone could be predicted.A series of surface quenching experiments with different surface quenching parameters,e.g.including arc current,anode diameter,scanning speed,etc.,were carried out.It was found that the hardness predicted by the proposed simulation model was in good agreement with the actual hardness,which verified the effectiveness of the proposed simulation model for the laminar plasma jet surface quenching of rail steel.
作者
余德平
张斌
宋文杰
郭达
彭科铭
YU Deping;ZHANG Bin;SONG Wenjie;GUO Da;PENG Keming(School of Mechanical Eng.,Sichuan Univ.,Chengdu 610065,China)
出处
《工程科学与技术》
EI
CSCD
北大核心
2021年第6期185-193,共9页
Advanced Engineering Sciences
基金
国家自然科学基金项目(51875372)
四川大学–宜宾市战略合作项目(2019CDYB–7)。
关键词
U75V钢
层流等离子体束
数值模拟
表面淬火
奥氏体化
U75V steel
laminar plasma jet
numerical simulation
surface quenching
Austenite formation
