Hot-rolled Versus Cold-rolled Steel and The Influence of Annealing
| Hot rolled | Cold rolled | ||
|---|---|---|---|
| Material properties | Yielding strength | The material is not deformed; there is no initial strain in the material, hence yielding starts at actual yield value as the original material. | The yield value is increased by 15%–30% due to prework (initial deformation). |
| Modulus of elasticity | 29,000 ksi | 29,500 ksi | |
| Unit weight | Unit weight is comparatively huge. | It is much smaller. | |
| Ductility | More ductile in nature. | Less ductile. | |
| Design | Most of the time, we consider only the global buckling of the member. | Local buckling, Distortional Buckling, Global Buckling have to be considered. | |
| Main uses | Load bearing structures, usually heavy load bearing structures and where ductility is more important ( Example Seismic prone areas) | Application in many variety of loading cases. This includes building frames, automobile, aircraft, home appliances, etc. Use limited in cases where high ductility requirements. | |
| Flexibility of shapes | Standard shapes are followed. High value of unit weight limits the flexibility of manufacturing wide variety of shapes. | Any desired shape can be molded out of the sheets. The light weight enhances its variety of usage. | |
| Economy | High Unit weight increases the overall cost – material, lifting, transporting, etc. It is difficult to work with (e.g. connection). | Low unit weight reduces the cost comparatively. Ease of construction (e.g. connection). | |
| Research possibilities | In the advanced stages at present. | More possibilities as the concept is relatively new and material finds wide variety of applications. |
Annealing, also described in the earlier section, is part of the manufacturing process of cold-formed steel sheet. It is a heat treatment technique that alters the microstructure of the cold-reducing steel to recover its ductility.
Read more about this topic: Cold Formed Steel
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