Investigation on Annealing Procedure for Large Casting Steel for CYCIAE-100

CYCIAE-100, a 100 MeV H-cyclotron under construction at China Institute of Atomic Energy, is a compact H-cyclotron. Since its upper/bottom and return yokes are each made of a casting steel of large dimension (with final dimension of 6160 mm in diameter and weight of 140 tons each piece), special attention has to be paid to the annealing procedure to insure the magnetic properties of this kind of large scale casting steel pieces with high purity. First, this paper presents an overview of annealing strategies to improve the magnetic properties of large scale casting steel. Then an estimation of heating time during annealing procedure has been made by FEM simulation based on the current status of annealing facility in China and has been indirectly verified by a rule of thumb from the results in TRIUMF design note. Based on that as well as on a close collaboration with CITIC HMC, the manufacturer of large casting steel mill, an agreement on detailed annealing procedure has been reached and issued for production of large casting steel for CYCIAE-100. The results from the practice have been obtained and the detail procedure will be presented in this paper as well.