Unbalanced structural performance
Large forgings are large in size, many in process, long in cycle, uneven in process history, and unstable in many components, so that the structural performance is often uneven, so that the mechanical properties test, metallographic structure inspection and non-destructive testing are not possible. experience. Due to the segregation of chemical components in steel ingots, the accumulation of assimilates, the influence of various porosity defects; the temperature change is slow during heating, the distribution is uneven, the internal stress is large, and the disadvantages are many; the high temperature long time casting, part of the force deformation, plastic flow The situation, the degree of compaction, and the variation of deformation are large; the dispersion process is slow during cooling, the structural transformation is complicated, and the additional stress is large. All of the above ingredients probably lead to uneven structural performance and unqualified quality.
Measures to improve the symmetry of large forgings:
1) Accept advanced smelting and casting techniques and improve the metallurgical quality of steel ingots;
2) Accept control casting, control cooling technology, optimize process history, and improve the economics of craftsmanship for large forgings.