Simulation Analysis and Research on Extrusion Process of Super Pipe Nozzle for Nuclear Power Station

Abstract

In order to study nozzle forming process of super pipe for nuclear power plant, the numerical analog simulation has been carried out on hot extrusion nozzle forming process of super pipe forging using France Forge simulation software. The results show that the billet temperature drop is the fastest in contact with the mold, and the high temperature zone exist in the heart of the billet. During the forming process, the temperature of the billet is above 750℃, and is in the range of reasonable hot forming temperature of the hot extrusion nozzle. The axial stress extreme value happen from the intermediate stage of forming period, the maximum radial stress is 37.2MPa, produced in the nozzle connection transition zone near the inner surface; the radial stress extreme value happen from the latter stage of forming period, the maximum radial stress is 98.5MPa, appear in the inner surface near the nozzle tip edge, meanwhile the part strain is 1.61. According to Cockcroft & Latham fracture criterion, the above two parts have a tendency to crack. The actual product and inspection shows that there are cracks in the above positions.