An enormous variety of metals and alloys have been fabricated for use in products throughout history. D+M Metal Products primarily uses steel for our projects, so we thought we would discuss which types of steel we use and what the benefits of these different types of steel are.
Different Types of Steel for Fabrication
The types of steel D+M Metal uses are primarily cold rolled or hot rolled pickled and oiled sheet metal. What do these terms mean?
The terms “cold rolled” and “hot rolled pickled and oiled” refer to distinct processes used in the production of steel sheet metal. Each has its own unique characteristics and applications. Understanding the differences between these two processes is important for selecting the right type of steel for your project’s needs.
Hot Rolled Pickled and Oiled (HRPO) Steel
The most basic form of carbon steel is hot rolled steel. During the forming process, the steel is rolled at a high temperature, typically over 1700°F, which is above the steel’s recrystallization temperature. This makes it easier to shape and form. Unfortunately, while the carbon steel coil is cooling, scale often develops on the surface of the metal which, for many manufacturing needs, is very undesirable.
To remove the scale and other impurities, the steel is then pickled by being bathed in a dilute solution of acid (usually hydrochloric or sulfuric acid). Finally, the steel is coated with oil to prevent rust. The surface finish will have a slightly oily surface due to this coating.
HRPO Properties and Applications
HRPO steel has a lower dimensional accuracy due to the high-temperature processing. It’s more malleable and easier to work which helps in applications that require forming and shaping, and it’s often used where the surface finish of the metal product is not a primary concern, such as in construction, or when it will undergo further processing like painting or powder coating.
There are different grades of hot rolled steel, including:
CQ – Commercial quality steel is ordinarily produced from a low carbon steel.
A36 – This is a mild carbon steel that works well for fabricating, welding, bending and cold forming.
High-Strength-Low-Alloy (HSLA) Sheets – HSLA steels have higher strength properties and improved formability, weldability and/or atmospheric corrosion resistance than conventional carbon sheet steels. They are typically 20-30% lighter than carbon steel at the same strength levels and lend themselves to applications where weight reduction is a major factor.
In terms of uses, HRPO flat rolled steel is excellent for plate burning and plasma cutting processes to manufacture and machine smaller, more precise components and parts.
Cold Rolled Steel
Cold rolled steel is a product that results from further processing of hot rolled steel. The hot rolled steel is rolled at room temperature between two rollers, and its original thickness is compressed. This increases the strength, ductility, and hardness of the steel. The temper, or hardness of the steel, depends on the strength of the compression during the cold rolling process.
Cold rolled steel also has more precise dimensions and is able to hold tighter tolerances than hot rolled steel. It’s suitable for stamping, forming, and moderate drawing operations.
The surface of cold rolled steel is smoother and cleaner with a more refined, attractive surface finish. Since it is not oiled like HRPO, its appearance is typically bright and shiny. It’s far better suited for use in consumer products and finished goods like appliances, metal furniture, and POP displays. It also provides an excellent substrate for baked enamel and lacquer finishes.
People may think that steel is steel, but there are many types of steel available, and they are used for different purposes. Hot rolled steel is better for applications where the material will be further processed, while cold rolled steel is suitable for applications where appearance and precision are more critical.
If you have any questions about your next metal fabrication project, D+M Metal Products would be happy to answer them. Contact us today at (616) 784-0601 to get started.