تجربی و تجزیه و تحلیل شبیه سازی شوک حرارتی با حرارت تند به دنبال آن آب برای رفع آلیاژ CuW70

By means of the rapid heating followed by water quenching, thermal shock experiments were conducted for CuW70 alloys to study the variations of mechanical behaviour. On the other hand, the simulation with finite element method was implemented to analyze the variations and the distributions of the temperature and the thermal stresses of CuW70 specimens during thermal shock process. The results show that the strength of CuW70 alloys degenerates and the ductility is improved after repeated thermal shock, and the maximum thermal stress appears at the beginning of heating and quenching period. The alternated thermal stresses which vary between tensile and compression stress will be applied on the internal and the external of CuW70 alloys during repeated thermal shock.

Because of the excellent thermal conductivity, thermal resistance and high strength, CuW alloys are used widely in high temperature environments sustaining thermal shock load. A common thermal shock (TS) configuration is for a component at an initially uniform temperature suddenly to be exposed to the medium at different temperatures. Therefore, rapid mutative temperature gradient induces thermal stress among the materials. In past years, experimental and simulation investigations on thermal shock behaviour of refractory materials were reported extensively in literatures[1-4]. The thermal shock test by water quenching in a bath of water at room temperature is a very popular one because of its simplicity[5-7]. Generally, a thermal shock study is considered with two points of view, e.g. thermal and mechanical aspects. Thermal shock stresses have specific mechanical characteristics compared to the steady-state ones. It means that for thermal shock study both the temperature gradient and the corresponding thermal stresses in materials vary suddenly according to the necessary time to attain the thermal equilibrium state. Moreover, the mechanical propertiesof materials under high thermal loading rates are changed due to the damage and plastic deformation of materials. The main objective of this paper is to bridge the thermal shock experiment and the mechanical behaviour of CuW alloys. Furthermore, finite element method is applied to study the internal thermal stress of CuW alloys under thermal shock loads according to thermal-elastic effect.

1) The ductility of CuW70 alloys is improved while the strength decreases simultaneously with the increasing number of thermal shock. 2) During heating and quenching of thermal shock, internal stresses reach to the maximum value at the beginning and decrease gradually with the increase of time, and return to zero value at the end of each thermal shock. 3) Tensile and compression stresses appear at the internal and the external of the specimens and replace each other during different thermal shock periods. Alternated loads are applied on alloys so that the plastic deformation and damage will take place on copper phase.