摘要
根据扫描电子束焊机实际工作状态，运用传热学理论，建立了球墨铸铁表面淬火三维温度场的有限元模型。分析过程中，考虑了材料的热物性参数随温度变化因素、试样表面的热辐射以及材料的相变潜热，对硬化层横截面形貌和尺寸进行了预测与实验验证。结果表明：电子束扫描作用下的温度场呈半卵形，对称面的温度分布等值线呈勺状。增加束流大小和扫描速度都可以改变硬化层的尺寸。经过电子束表面淬火后，形成了淬硬层、过渡层和基体3个区域，与基体硬度相比，淬硬层的显微硬度提高了2—3倍，过渡区也提高了1～2倍。实验结果较好地验证了仿真结果，表明所建立的温度场模型是正确和可靠的。通过该仿真模型，可以掌握电子束表面淬火过程中加热和冷却规律，为电子束表面淬火处理选择合适的工艺参数提供依据。
A 3D FEM model of the temperature field for electron beam quenching of ductile iron was established, according to the actual experimental condition of scanning electron beam welder. In the course of analysis, the heat transfer theory was applied. The relation of the thermal physical parameters with temperature, the phase transformation and thermal radiation were considered. The feature of hardened layer and the size of hardened zone was calculated and experimented. The results show that the temperature field caused by electron beam is half of oval shaped and the temperature distribution of symmetry plane is spoon- shaped. Increasing the current and the speed can both enlarge the size of hardened layer. Three different zones form after electron beam surface quenching,i, e. quenching zone, transition zone and substrate. Compared to the substrate, the microhardness of quenched zone increases by 2 - 3 times and that of the transition zone increases by 1 - 2 times. The obtained experimental results show a good agreement with the simulation results. It indicates that the established numerical model is correct and reliable. The model provides a guide for study on the rule for the heating and cooling of scanning electron beam surface hardening of ductile iron. The results can be used to optimize the Drocessinz parameters.
出处
《材料热处理学报》
EI
CAS
CSCD
北大核心
2013年第9期189-194,共6页
Transactions of Materials and Heat Treatment
基金
广西自然科学基金(2010GXNSFA013028
2012GXNSFDA053026)
桂林电子科技大学研究生创新项目(XJYC2012004)
关键词
电子束表面淬火
有限元仿真
温度场
硬化层
electron beam surface quenching
FEM simulation
temperature field
hardened layer.
