管轴透盖裂纹失效机理及铸造工艺优化OA

Aiming at the crack failure problems of the tube shaft through covers applied for large rotating machinery,and through a method of combining multi-scale characterization and numerical simulation,the crack failure mechanism of the HT250 through cover was systematically analyzed,and the casting process was optimized.It is found through investigation that the cracking failure is primarily caused by localized accumulation of type-E graphites,whiches destroying the matrix continuity and inducing microcracks and extending under the effects of alternating loads.Through increasing the carbon equivalent to 3.9 and raising primary inoculation addition to 0.43％,the type-E graphite formation can be effectively suppressed.Furthermore,by optimizing the casting process and cooling rate by using of MAGMASOFT software,and adding riser at the position of wall thickness variations,and adjusting melting processes,the casting defects have been significantly reduced,leading to substantial improvement in product qualification rate.