Numerical Simulation Of Solidification And Stress For Incoloy800Superalloy Slab Continuous Casting Process

Incoloy800superalloy that is an iron-based alloy, with high temperature strength, good antioxidant properties, anti-carburizing properties and impermeability of sulfur, is a common engineering alloy. Continuous casting technology of superalloy doesn’t put into production in China now. As foreign countries are keeping secret for this technology and the domestic demand for superalloy is also increasing, the development of continuous casting technology of superalloy has become an important task at the present stage. In continuous casting process, the superalloy has easily leaded to crack due to its special mechanical properties. In this paper, using an established superalloy slab continuous casting model, the solidification process and stess distribution of superalloy slab have been simulated.The development and application of superalloy, the features of Incoloy800alloy and the continuous casting technology of supperalloy are reviewed. Also the types and generation mechanism of slab cracks are analyzed. According to superalloy’s material composition and some measured physical parameters, the database of thermal properties and high temperature mechanical properties of Incoloy800superalloy is established by using the ProCAST thermodynamic model. A three-dimensional heat transfer model and elastic-plastic constitutive equations are developed. Bassed on ProCAST commercial software, MiLE algorithm coupled with user program are used to simulate solidification and thermal stress in the continuos casting process. The effects of some parameters on the distribution of temperature and stress are discusted.The results show that:(1) with secondary cooling heat transfer coefficient increasing, temperature recovery is higher, which may result in cracks. The greater the pull speed, the greater the liquid-core depth and the thinner the solidified shell thickness, as a result, the slab will be easily abruption and form cracks. In the simulation of solidification process of superalloy continuous casting process, it is necessary to consider the effect of the air gap.(2) Surface horizontal cracks is prone to be generated at the bottom part of the superalloy billet, However, surface longitudinal cracks and corner cracks are prone to be produced near the corner. The greater heat transfer coefficient of secondary cooling zone, the greater the effective stress. The effect of casting speed on effective stress is more complex, and further researche should be conducted in the future experiment. For superalloy casting mold, it is necessary to optimize the mold taper according to solidification shrinkage.(3) Hot cracking index is used to predicted orientation possibility of slab cracks. For high-temperature alloy billet, the crack sensitive locations are located in the slab’s corners and near the narrow surface. Stress or temperature distribution can not be a good criterion for the crack prediction.