Ziliang Li

Numerical Simulation of the Mechanical Properties of Cr12 Steel during Gas Quenching

Heat treatment is one method to improve mechanical properties of metal, but each heat treatment method has its advantages and disadvantages, therefore, different requirements regarding size, shape, and properties with respect to different heat treatment processes should be considered. Gas quenching is a heat treatment process used in various industries such as the aerospace, automotive, machine tool, and other advanced manufacturing processes. The use of gas quenching can significantly improve the mechanical and physical properties of a material. Simulation of gas quenching processes is becoming increasingly important, although not common, for the investigation of mechanical properties and their effects on quality. This paper is based on the theory of phase transformation, computational mechanics, thermal nonelasticity, and the character of the gas quenching process. A nonlinear heat conduction equation considering phase transformation is developed and a model of the relationship between the phase transformation products and the properties of Cr12 steel are established and solved using the finite element method (FEM). By comparing calculated results with those of experiments, satisfying agreement is found. It is anticipated that this model will be valuable for further theoretical development and practical applications.

A COMPUTATIONAL ANALYSIS OF THERMAL RESIDUAL STRESS DURING MAGNETIC QUENCHING

In this paper, based on the analysis of coupling action of temperature, phase transformation, magnetic field and stress, the phase transformation condition and equation related to material properties are discussed, a new constitutive equation considering effects of phase transformation and magnetic field is proposed and solved by means of Finite Element Method (F.E.M). The thermal residual stress is obtained and the influencing factors on the thermal stress of magnetic field are analysed and discussed.