【作者】 姜明昊；

【导师】 杜凤山； 王敏婷；

【作者基本信息】 燕山大学 ， 机械设计及理论， 2009， 硕士

【摘要】 楔横轧是一种高效的轴类零件塑性成形工艺,用楔横轧工艺成形非调质钢具有节能降耗的显著优势。本文以三辊楔横轧工艺为研究对象,对典型非调质钢热成形微观组织演变开展物理模拟研究,建立了耦合热、力、微观组织演变的有限元数值预报模型,分析了非调质钢空心轴热成形过程,并结合实际轧制试验验证了模型的正确性。利用Gleeble-3500热/力模拟试验机进行热模拟试验,采用单/双道次压缩试验和金相分析相结合的方法,研究了典型轴类件用非调质钢40MnV在楔横轧工艺范围内的力学行为及微观组织变化,并得出了相应的数学模型,包括再加热过程的晶粒长大模型、变形过程中的动态再结晶动力学及晶粒尺寸模型、变形间隔时间内的静态再结晶动力学及晶粒尺寸模型、再结晶后的晶粒长大模型、变形抗力数学模型等。研究了微合金元素对再加热及再结晶过程的抑制作用。所有这些模型的建立为深入开展控制轧制、轧制过程虚拟仿真及产品组织性能预报的研究奠定了基础。基于热模拟试验得出的微观组织模型,对DEFORM软件进行二次开发,建立了40MnV钢空心轴三辊楔横轧轧制过程三维热、力、微观组织演变耦合的非线性有限元计算系统,并对三辊楔横轧轧制过程进行分析,研究各种场变量及晶粒尺寸的分布规律。在三辊楔横轧机上开展空心轴非调质钢楔横轧成形试验,通过测量轧件晶粒尺寸,验证了热模拟试验所得到的组织演变数学模型的正确性。应用该微观组织模型,利用编程语言VB6.0编制了用于模拟计算40MnV钢热轧微观组织演变的可视化程序,可通过改变参数实现微观组织预报,对实际生产具有指导作用。更多还原

【Abstract】 Cross wedge rolling is a efficient shaft processing technique. It has advantage on saving sources that the non-quenched and tempered steel used in cross wedge rolling. In this paper, with a investigation of three-roll cross wedge rolling, the hot-forming microstructure changes of non-quenched and tempered steel were investigated. Numerical simulation for hot-forming process of non-quenched and tempered steel hollow shaft is executed with the thermal, mechanical and microstructural evolution coupled. And then simulation results are verified in combination with actual rolling experiments.In the paper, compressed tests were carried out by using thermo-simulation machine Gleeble-3500. The mechanical behavior and microstructural changes of the typical shaft non-quenched and tempered steel 40MnV for cross wedge rolling are investigated by using single/double-hit compressed tests and metallographic analysis. Mathematic models were established, involving: grain growth model during reheating, mathematical empirical equations with the kinetics of dynamical recrystallization model during hot forming, dynamical recrystallized grain size model, the kinetics of static recrystallization model after hot working and grain size model, grain growth model after recrystallization, mathematic model of deformation resistance. Also, the restraining functions of carbonitrides have been investigated, which were acted on on reheating and recrystallization process. The establishment of all of these models lays a foundation for further developing controlled rolling, virtual simulation of part rolling process and prediction on microstructural properties.Non-linear rigid-plastic finite element method model has been build for simulating the three-roll cross wedge rolling process of steel 40MnV hollow shaft with the thermal, mechanical and microstructural evolution coupled. The model has been build on the platform of DEFORM software with the aid of redevelop based on the mathematic models obtained from physical simulation tests. The distributions of temperature strain, strain rate, stess and grain size of workpiece were analyzed respectively. The hot rolling experiments were carried out by three-roll cross wedge rolling mill. The microstructural models obtained from physical simulation tests were validated by contrasted with grain sizes of workpiece. The visual program for steel 40MnV rolling microstructure changes was developed by VB6.0 programming language based on the mathematic models in this paper. It can realize prediction on microstructure by changing technological parameters and guided the actual manufacture.更多还原