Steel: Hot & Cold Rolled Bar and Hot & Cold Sheet Metal
Hot Rolled Bar Steel
The application of heat during processing at the steel mill can affect the qualities of the steel. The alloys present in the steel are affected by both the application of heat and by how long the steel is rolled (longer usually equals stronger).
Hot rolled bar steel involves rolling the steel at very high temperatures that are beyond the recrystallization temperature. Thus molten, the steel can be easily shaped and formed into various larger sized products such as railroad tracks, I-beams, tubes, pipes, round and flat bars, angles, expanded metal, etc. Hot roll bar products are popularly used in the construction and welding trades.
No reheating is required (as is the case with cold rolled steel), so there tends to be minimal delay in processing these materials. Contact Metaltech to order your hot rolled bar steel.
When hot rolled steel cools down, it shrinks a bit and the size and shape also tend to change slightly because there is little control over the cooling process. Hot rolled steel is less expensive and is used when exact precision is not a vital consideration for the end use of the steel.
Cold Rolled Bar Steel
Cold rolled bar steel is processed more than hot rolled bar steel. It is cold finished in various ways (such as by turning, cold drawing, grinding, polishing, etc.) to eliminate surface imperfections, increase the steel’s tensile strength, size the steel to within tolerance, and to provide an attractive finish.
Cold finished bars have higher carbon content than hot rolled bars and can be a little more difficult to work with. However, they are far superior in concentricity, straightness, tolerance, and finish in comparison to hot rolled bar steel. Tensile strength is approximately 20% higher and yield is approximately 50% higher than that of hot rolled bars. Cold rolled bar is much easier and faster to machine than hot rolled bar, also. This results in less waste and decreased overall cost of parts.
Hot Rolled Sheet Metal
Metaltech provides hot rolled sheet metal that was formed at over 1,000°F. It has a characteristic, rough, blue-grey finish and is suitable for standard sheet metal applications where appearance and tolerance criteria are not strict.
Cold Rolled Sheet Metal
Cold rolled sheet metal is superior to hot rolled sheet metal in the following manner. It has a strictly controlled tolerance, concentricity, straightness, and a blemish-free to nearly blemish-free finish. It has lower carbon content and has been annealed (heated to a high temperature) and is, therefore, softer and easier to work with than hot rolled sheet. Additionally, surface oxides have been removed, resulting in an attractive, gleaming finish.