Research Of Stainless Steel304Triple-valve Body Multidirectional Extrusion Deformation

304stainless steel products are widely applied in the field of military, nuclear power, petrochemical and other important fields for its excellent chemical stability and good processability, especially in the high corrosion resistance requirements such as ships and nuclear reactors of storage space, cooling system, transport system. As austenitic steel, the casting intensity of304is low, can’t be strengthened with heat treatment at the same time, and can’t meet the demand of the use of high temperature and high pressure system components, severely restricting its application scope. The strength can be improved by plastic processing, but the deformation mode and degree produce a great impact on the microstructure and mechanical properties. In this paper, homogeneous austenitic stainless steel triple valve body was obtained by multidirectional extrusion under200℃, through research on the microstructure of304alloy in cold deformation state and the active load to realize flexible control. The deformation process improve the overall performance of the material from two aspects of deformation strengthening and refined crystalline strengthening at the same time.The transformation law of was studied304alloy rheological stress changing with the deformation temperature and deformation rate, temperature deformation condition rheological stress calculation model was established. The influence of plastic deformation energy and elastic distortion energy was discussed form phase transition thermodynamics. Research shows that the material can’t produce deformation defects while compression strain reach more than1.2at200℃, and do not produce martensite phase transformation and the second phase precipitation in the process of deformation. Deformation texture was single austenite, and the deformation resistance was decrease with room temperature deformation. The experimental study and numerical simulation was done for the triple valve body deformation process by multidirectional active load, and flow characteristics and strain state of different deformation zone was analyzed. Metal flow trend and defect forming conditions was studied through divided the workpiece into several parts, the mechanics reasons for defect formation was analysesed, defect formation mechanisms was revealsed in the process of multidirectional deformation.The workpiece produce streamline crossover caused by active load cross under the condition of multidirectional stress, the partes with multidirectional tensile strain produced tends to stretch gap, and multidirectional compressive strain to streamline folding.The deformation law of multidirectional active loades and multidirectional extrusion area was studied, alternating deformation characteristics of strain-hardening alloy with different deformation area was founded in stable deformation stage; the velocity field of flow function was obtained with multidirectional loades, alternating deformation discriminant in multiple deformation area was deduced based on energy theory, the flow equation was determined.The contribution to reduce the local the non-uniform deformation degree was discussed for materials couette flow with moving die. More active moving dies can get multiple couette flow deformation zone, the deformation parts of workpiece evenly deformed.The research shows that the multidirectional warm extrusion experiment of304stainless steel triple valve body was studied, the profile and inner hole was formed will two step multidirectional extrusion forming in200℃. Studies have shown that two step more moving dies active load can reduce deformation extent, increase deformation uniform. Deformation process does not change the material microstructure, and the deformation strengthening and fine-grain strengthening was obtained, therefore, the intensity of material increase3-4times under the condition of not reducing its corrosion resistance,, largely improve the comprehensive mechanical properties of the material.