| As an important assembly unit of the major equipments, the heavy forgings’ production capacity and technical level is a symbol of the development level of a country. When heavy forgings in high-temperature forming and cooling process, the hydrogen will be separated out and aggregated in forgings internal micro defects and lead to cracks initiation because of high hydrogen pressure, which called hydrogen embrittlement that are the most knotty and dangerous defects in heavy forgings. In this paper, the high hydrogen embrittlement sensitivity alloy steel is used as the research object. By adopting the combination of physical simulation and finite element analysis method has carried on the comprehensive research on hydrogen diffusion and the mechanism of hydrogen embrittlement damage of the large forgings.Firstly, in this paper, commonly used hydrogen embrittlement mechanism and hydrogen diffusion model was introduced, while the constitutive equation of hydrogen diffusion model is discretely deduced.Secondly, for large forgings, the whole process of heat treatment is in the process of hydrogen diffusion. In order to detect the content of hydrogen in steel at any time, it is necessary to know the permeation rate of hydrogen in steel. This paper is based on Fick’s second law, hydrogen diffusion coefficient of alloy steel which has different components was determined by the electrochemical workstation and its matching test software. A new method for determination of hydrogen diffusion coefficient in metal materials is presented.Thirdly, in this paper, two different kinds of alloy steelwith different Cr content are studied by electrochemical hydrogen charging tensile test,the degree of hydrogen embrittlement is measured by varying the amount of elongation of hydrogen embrittlement index. Which hleps to study the influence of Cr content on the susceptibility to hydrogen embrittlement of steel.And the hydrogen-induced damage irreversible can be verified by hydrogen charging- tensile test and hydrogen filling- place- tensile test.Finally,hydrogen pressure inside the bulgeis backcalculated by finite element method electrochemical hydrogen charging on the basis electrochemical hydrogen charging, which toget thequantitative analysis of the hydrogen pressure and the hydrogen content in the forging hole. The growth rules ofhydrogen bulge and hydrogen bulge pressure calculation can be studied with the help of establishing hydrogen concentration and micro pore pressure contact, which is used of solving the problem that micro-pores or hydrogen segregation zones are often located in the interior parts in metallic material anddifficult to directly measure. |
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