Various methods exist for manufacturing stainless steel profiles, each presenting unique advantages. Notably, hot rolled profiles possess specific and defining characteristics.
Profiles can be rolled at high temperatures, known as hot rolling, or at room temperature, referred to as cold rolling. The temperature during rolling significantly influences the outcome. Both techniques allow for the production of stainless steel profiles, be it hot rolled or cold rolled. However, the inherent properties of these methods exhibit clear disparities.
The process of hot rolling sections stands out as the most efficient technique for manufacturing elongated bars. Once the mill is configured and operational, it facilitates the production of extensive quantities of hot rolled profiles with exceptional productivity. Typically, temperatures soar above 1,100 degrees Celsius. This temperature is reached by billets or blooms in the traditional "start-stop" production method, or wire rods in the "endless" rolling method. Multiple roll stands subject them to plastic deformation. The desired dimensions and weight of the raw material are determined by the geometry and lengths of the intended finished hot rolled profiles.
Hot rolling remains the quintessential method for mass-producing long products. However, in terms of precision and surface finish, certain limitations may need to be acknowledged.
Cold rolling profiles utilize wire rods as their raw material, which serve as semi-finished products. The rod's diameter is contingent upon the cross-section of the intended final product. Similar to the continuous process of endless hot rolling, cold rolling operates at room temperature. The production machinery guides the wire through various stands, shaping it into the desired form through multiple passes. This process results in a reduction of the metal's grain size, enhancing its hardness while rendering the surface smoother and more lustrous.
For intricate profiles, a multiple rolling process might be necessary, necessitating annealing before subsequent rolling.
This technology facilitates the creation of profiles with precise tolerances, making it an ideal method for crafting small to mid-sized special cold rolled profiles in stainless steel.
Cold-drawn bars exhibit superior surface finish, precise tolerances, and straightness compared to their hot rolled counterparts. Hot rolled stainless steel surfaces often display scaling, imperfect edges, and distortions.
Hot rolled stainless steel is less time-consuming and cost-effective when compared to cold-rolled stainless steel.
Conversely, cold rolled stainless steel showcases greater strength and hardness than its hot rolled counterpart.
The popular austenitic stainless steel grades 304, respectively 304L, as well as 316 or 316L and 316Ti are suitable for producing hot or cold rolled sections. This does secure the availability of stainless steel profiles on the market.
Some of the stainless steel grades lose their characteristic benefits when heated and therefore the final product might have other undesired features. Other materials might be too hard and tough, hence a mechanical cold deformation by rolling at room temperature is impossible.
