Simulation Research On Surface Materials' Temperature Distribution Of Hot Forging Die

Nowadays hot-forging die plays a great important role in metal forging processing, especially in the areas where metals are hard to be deformed. However it always bears cyclical thermal and mechanical loads in its working processing. As a result it has hardly a long service life on account of working in severe service. The current reseaches show that, the thermal stress, induced by the variation of temperature field, is the main cause of the failure and damage for the hot-forging die. The reason why low-cyclic thermal fatigue deformation comes in to being to bring about plastic deformation of die cavity to make hot forging die fail and damage is that crest value in temperature stresses is far larger than yield stress on the its surface. In order to extend the service life of hot-forging die, we have to resolve the problem aroused by the thermal stress with multilayer metal materials.In this paper, the die material H13 and Inconel 625/SiCp were selected separately as surface materials and simulated on their surface temperature distributions by means of optimized design of die materials.Part One, presented the existent questions with the development of hot forging die, particularly the high cost of manufacture and short service life. Afterwards the illustration was made for the styles and influencing factors of the failure and damage of hot-forging die. The hypothetical struction of hot-forging die was offered in response to the thermal stress in hot forging process.For the purpose of optimizing design of die materials, the surface temperature distribution and size of thermo-mechanical loads should be accurately realized in hot forging process and hot-forging mathematical model to be built. Part Two presented thermodynamic theories, including the terminal and initial conditions of differential equation of thermal transmittance and thermo-mechanical theory.In Part Three, regarding DEFORM-2D program as a tool, the work course of hot-forging die was simulated, in different craft parameters, physical properties and skeleton patterns. And then, the maximum surface temperature and the thermal penetrating depth in die cavity were calculated, which would be fundamental parameters on predicting die damage styles superficial treatment, as well as properties. The effects of craft parameters, physical properties and skeleton patterns on the maximum surface temperature and penetrating depth of high thermal flow density were investigated. The obtained data were then put into OrginPro so as to find out the rules.In Part Four, the lower die model of a wheel hub, being as an example, was simulated on its surface temperature distribution. The precise analysis was made on the temperature gradient and temperature fluctuation of the close superficies and superficies of a wheel hub in initial and stable forging process. Meanwhile, considering the service performance and requirement against thermal stress, the advanced materials and design innovative die struction are adopted as follow:(1) H13(5CrNiMo)being as bulk material in the area of temperature balance and elimination of heat.(2) W6Mo5Cr4V2 being as a close superficies material in layer of heat resisting.(3) Inconel 625/SiCp being as a superficies material in layer of heat resisting.At last, a multilayer metal die model, in accordance with innovative die struction was built, by adding W6Mo5Cr4V2 and Inconel 625/SiCp as coatings. Then the multilayer metal die model was simulated with Deform-2D software under the condition of its surface temperature distribution in order to indicate that multilayer metal hot-forging die could make sense to availably bring down the value of surface temperature and reduce the size of temperature fluctuation. Furthermore the surface temperature distribution of multilayer metal hot-forging die might be influenced by variation of physical property of materials related with temperatures.The calculation and analytic results show that, craft parameters, physical properties and skeleton patterns influence the surface temperature distribution of homogeneous die materials, and the innovative die struction and advanced materials are presented further to build the multilayer metal die model in response to overcoming the thermal stress. It is believed that these designs will help to increase the service lifetime of hot-forging die a lot.