Seven Types of Annealing Methods Part4


Process: The heat treatment process of heating the ingot, casting or forging stock to a temperature slightly lower than the solidus for a long time, and then cooling slowly to eliminate the non-uniformity of chemical composition.

Objective: To eliminate dendrite segregation and regional segregation during solidification of ingot and homogenize the composition and structure.

The heating temperature of diffusion annealing is very high, usually 100~200 ℃ above AC3 or ACCM. The specific temperature depends on the degree of segregation and steel grade,

The heat preservation time is generally 10~15 hours. After diffusion annealing, complete annealing and normalizing are required to refine the structure.

It is applied to some high-quality alloy steel and alloy steel castings and ingots with serious segregation.