The Solidification And Shrinkage Process Of Diffuser And Process Optimization For Casting

Diffuser is an important part in spray pump of containment, which belongs to the internals of pressurized water reactor pump without compression. Its material is ZG0Cr13Ni4 Mo which is a kind of stainless steel made of low carbon martensite. Because diffuser is the part of nuclear safety related equipment, all of its requirements is very strictness. There isn’t the defect including delamination, crack, blister, sinkhole, shrinkage porosity after the tensile test, impulse test, penetrant test, radiographic test, dimensional inspection. The requirement about the dimension of diffuser is relatively high because of the parameter request on spray pump. The construction of the casting of diffuser is relatively complex, which has screwy runner and biggish structural gradient. It has biggish percentage of contraction and is easy to turn up the defect of contraction besides hard to guarantee the dimensional accuracy because the material is influenced by alloying element.This article solves the problem which exist in the productive process of casting about diffuser in company combine with the actual production status. This article uses the software which named UX8.0 to establishing three-dimensional model and uses the simulation software about casting which named Any Casting to numerical simulation about initial process program after introduces the design case of initial process program. Through the analysis about filling process and caky process, the article predicts the possible shrinkage defects. The analysis indicates that the simulation result of software fit with the practical production results. In allusion to the shrinkage and dispersed shrinkage in the initial process program, place a circle of surface densener of uniform arrangement on the lower surface of casting, add a blind riser in the bottom flange of casting; analyze the question of size error and draw a conclusion that molding Shrinkage can’t meet the requirements of size precision. Determine the parameters of core box through the data of 3d scanning. Design the orthogonal experiment to analyze process parameter and obtain the best process parameter. The result of numerical simulation and the production practice indicate that the improved process program is useful to improve the quality of casting, the Improvement measures is effective.This topic combined the technology of CAD and CAE to solve actual problem and eliminate the shrinkage and dispersed shrinkage, make the size precision of casting meet the requirement, and provide the reference for casting production with the same material.