Defects and Countermeasures of large forgings: Uneven microstructure and properties

Large forgings, due to their large size, many processes, long cycle, non-uniformity in the process, and many unstable factors, often cause serious non-uniformity in the microstructure, so that they cannot pass the mechanical property test, metallographic inspection and non-destructive flaw detection.

Due to the segregation of chemical composition, inclusion accumulation and various pore defects in the ingot;
When heating, the temperature changes slowly, the distribution is uneven, the internal stress is big, the defect is many;
High temperature and long time forging, local stress and local deformation, plastic flow status, degree of compaction, deformation distribution is greatly different;
During cooling, the diffusion process is slow, the tissue transformation is complex and the additional stress is large.
All the above factors may lead to serious inhomogeneity of tissue performance and unqualified quality.
Measures to improve the uniformity of large forgings:
1. Adopt advanced smelting technology to improve the metallurgical quality of steel ingot;
2. Adopt control forging, control cooling technology, optimize technological process, and improve the technical and economic level of large forging production.