离心复合铸铁管消除铸造应力退火的研究

Study on Relieving Casting Residual Stress during Annealingfor Centrifugal Casting Composite Iron Pipe

外层为镶硬铸铁,内层为珠光体型球铁的离心铸造复合管件,在消除铸造应力退火过程中,其应力的变化是不同于单一材质铸管的.在退火保温的初期,内层珠光体的部分分解,使宏观的铸造残留应力较快地减小.继续延长保温时间,当外层珠光体部分分解时,则使管件的宏观残留应力增大.本文所述离心复合管件,消除其残留应力的最佳退火工艺为:450℃保温6小时炉冷.探讨了晶粒内应力变化的原因.

The stress change during relief annealing for the composite tubular products of the centrifugal casting, the outer layer of which is nickel-chilled cast iron and inner layer is pearlite ductile iron, is different from that of noncom-posite one. Early in the holding temperature of annealing, the partial decomposition of pearlite in the inner layer reduces strongly casting residual stress, if the temperature continues to hold, the partial decomposition of the pearlite in the outer layer leads to increasing casting residual stress of tubular products. The optimal technique for relief annealing of casting composite iron pipe are. holding at 450℃ for 6h and then cooling in furnace. The stress change in crystal grain is also discussed in this paper.