When purchasing material, it’s hard not to get sticker shock. Costs have more than doubled on most types and grades over the past year. With those increases comes the need to understand exactly what you are buying so you can make an educated selection of the best material for your application at the lowest cost. When buying mild steel plates, there are two common varieties for you to choose from, and the devil is in the details.
Hot Rolled vs. Cold Rolled Steel
All steel is the same, right?
When selecting the type of steel for your steel plate you need to understand the difference between the two common varieties, cold and hot. Knowing the difference between their price and precision can greatly affect your end results.
So what are the differences between hot rolled vs cold rolled steel?
Hot Rolled Steel (HR A36, HR A1011, HR A1018, etc.)
Steel becomes much more malleable when heated. To manufacture a hot rolled steel plate, a billet is heated in a furnace at a temperature of about 1700° F, then fed into giant rollers which impart thousands of tons of pressure to form the material with a fair degree of accuracy.
It is passed through the rollers multiple times until the desired dimensions are achieved. After forming, the plate cools and the shape is set. Because steel shrinks as it cools, the final dimensions of hot rolled steel are not as precise as the cold rolled variety.
A hot rolled steel plate will typically have the following characteristics:
A somewhat rough, scaly finish
Slightly rounded edges from being fed through rollers
Slight distortion and loss of dimensional accuracy.
Because it costs less to process, hot rolled steel is typically less expensive to buy. For non-critical applications, the cost savings might be an acceptable tradeoff for dimensional imperfections and a rough finish.
If your finished product needs to have a high degree of dimensional accuracy and a smooth finish, plan to spend more time fabricating hot rolled material to achieve your desired results. Hot rolled steel is also often offered in a “Pickled & Oiled” or “P&O” variety, which has been picked in acid to remove mill scale, then oiled to prevent rust.
Cold Rolled Steel (A653, A879 CQ, A1008, etc.)
Cold rolled steel starts off as hot rolled steel. After cooling, the hot rolled steel is then annealed or tempered. The cold rolling process improves dimensional accuracy and produces a better surface finish.
Cold rolling also increases the strength of the material up to 20%. This allows cold rolled steel to be used in applications that require a greater degree of precision and hardness with increased wear resistance and a lower likelihood of deformity. Cold rolled steel will also require less work to achieve a paint-ready surface finish.
Cold rolled steel will be:
Smoother and more uniform in appearance
Squared on the edges
More likely to warp when heated
Expect to pay about twice as much for cold rolled steel, but you’ll be getting a better product for your money that will require less fabrication time to produce a finished product. Either way, plan on bringing a trailer to the supply house: loaded with money to pay for the steel and then to carry it back to your shop while crying.
Want to learn more about hot rolled vs cold rolled steel? Visit our website or call 800-342-8477. Whether you are looking to do business with us or just want to learn more, we’re here to help!
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