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Metallurgy/heat treatment


sir please give difference between annealing and solution annealing process and applications..

Annealing in general may be used to describe thermal treatment processes.

In steels, full annealing, sometimes simply referred to as annealing, is a term used to describe the heat treatment resulting in a microstructure consisting of coarse pearlite (and pro-eutectoid phases in the case of hypo- or hyper-eutectiod alloys). To obtain this type of microstructure in plain carbon and low-alloy steels, cooling rate after austenitization must be low (e.g. furnace cooling). The above microstructure is relatively soft and therefore suitable when the next processing step involves extensive machining or cold deformation operations.

Solution annealing, on the other hand, is commonly used in the context of alloy steels (stainless and tool steels). The high alloy content of such steels facilitates the formation of carbides with a higher stability than the cementite. To ensure that all these carbides are dissolved in the matrix, the annealing process must be done above the dissolution temperature of precipitates and this temperature depends on the chemical composition. For instance, stainless steels containing high Cr and C contents readily form Cr carbides and therefore require heat treatment at high temperatures, commonly above 1000 C, when the applicable standard calls for the full dissolution of precipitates.  


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Javad Mola


I welcome questions related to the physical metallurgy of steels, preferably stainless steels.

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