.304 L Stainless Steel High Temperature Static Softening And Grain Growth Of The Law

Nuclear power is one of lowest unit cost power resources,which is important energy for the sustainable development of national economy. Heavy forging is the main basic components of nuclear power equipment, At present, China's technology of manufacturing large forgings still has a large gap compared with foreign advanced level. 304L steel that is the main structural materials of nuclear power equipment needs higher forging process, and structure property is difficult to control in multi-pass forging process especially. Focusing on the steel 304L hot forging structure property characteristics, this paper deeply researches on multi-pass deformation intermittent static softening behavior and grain thinning methods of 304L steel, and explores the evolution mechanism microstructure of 304L steel.Through analysis of 304L steel hot deformation mechanical behavior and organizational characteristics in cast and forged state, it comes out that compared with cast steel, forged steel showed a lower state of flow stress curves, process of dynamic recrystallization is obviously slow, when heat distortion temperature is above 1050℃, the occurrence of dynamic recrystallization will be benefited; when forging steel in 1050℃, state easy to obtain more uniform and fine dynamic recrystallization.According to relationship between grain growth and temperature and holding time through static recovery process, it sets up a grain growth model; study found that the grain size grew rapidly during the initial holding time, and then growth trend gradually slow down, which indicate that the impact of holding time on the grain size is relatively weak.By double-pass hot compression deformation test, this thesis sets up astatic recrystallization rate model, and analyses factors in the static recrystallization process. The results are showed that: the higher the deformation temperature, the higher the strain, the more refined the grain, the faster the static recrystallization, the more complete the extent. Based on the changes in the dislocation density, building the model of static recrystallization rate and relation between dislocation density and time through static recovery process. According to the changes of dislocation density of TEM experiments in double-pass process, it is found that at the end of static recrystallization, dislocation density is back to what it was before deformation; the result of X-ray diffraction and XRD analysis showed that the crystal structure of 304L Steel deformed is FCC, and the deformation microstructure dislocation is mainly dislocation tangle and local cellular substructure.In short, through analysis of grain refinement process, grain growth, dislocation evolution mechanism in strain process and gate batch process on steel 304L stainless steel, reveal rules of grain growth and refinement of 304L austenitic steel and dislocation evolution features and grain refinement rules in static recrystallization, hoping to provide Technical support for Improve the level of large forgings manufacturing technology.