Did you ever wonder how stainless steel manufacturers turn stainless steel into the products that are so ubiquitous in Perth?

What is Stainless Steel?

Stainless steel is an alloy of steel and other metals. It contains at least 12% chromium, which provides its resistance to rust or staining. Nickel is added for most applications in the food and beverage industry. Stainless is used in the food and beverage industry because it is easy to clean and keep sanitary. It is also very durable and protects the flavour of food and beverages.

Austenitic stainless steel contains 6% or more of nickel and austenite, producing a face-centred cubic structure which promotes ductility and corrosion resistance. Ferrite stainless steel contains ferrite, which has a body-centred cubic structure. It is more resistant to stress corrosion but tougher to weld.

Duplex stainless steels are a combination of ferritic and austenitic. They provide superior resistance to cracking, crevice corrosion and pitting and provide twice the strength of most austenitic steels.

Raw Materials

Stainless steel is made of iron ore and chromium. Other materials that may or may not be added in various amounts: nickel, manganese, molybdenum, nitrogen and carbon. Each element contributes to a certain property. The final mixture is determined by the desired properties.

Making Stainless Steel

The raw materials are put into an electric furnace where they are melted by intense heat over a period of between eight and twelve hours. They are then cast into semi-finished shapes such as rectangular shapes called “blooms,” round or square shapes called “billets,” rods, slabs and tube rounds.

Forming

Next, the steel is heated and then passed through rolls in a procedure called “hot rolling.” Billets and blooms are formed into wire and bar, while slabs become strips, plates or sheets.

Heat Treatment

The next step is called “annealing,” where the steel undergoes heating and cooling under controlled conditions. This softens the metal and relieves internal stresses. Some of the metals are then subjected to age hardening, in which they are heat treated to become even stronger. This process has to be exact to obtain the desired result.

Lower temperatures in heat treatment cause more strength with less resistance to fractures. Higher temperatures produce a material that is tougher but not as strong. The temperature has to be within certain tolerances to produce stainless steel that is both strong and durable.

De-Scaling

The annealing process causes “scaling” to form on the steel. The scaling needs to be removed; the most common methods are pickling and electrocleaning. Pickling uses a bath of nitric-hydrofluoric acid. Electrocleaning uses a cathode in tandem with phosphoric acid.

Cutting

Cutting is the method by which the desired blank shape is obtained. It is also the method used for trimming a part to final size. Stainless steel can be cut mechanically by techniques such as straight shearing with guillotine knives. Another technique: circle shearing with circular knives. High-speed sawing can be done with steel blades.

Metal punches and dies can be used in a process called “blanking.” A variation of blanking called “nibbling” can be used for irregular shapes. Stainless steel can also be flame-cut using a flame-fired torch emitting oxygen and propane. Plasma jet cutting employs an electric arc in tandem with an ionised gas column.

Finishing

Finishing is important. If a dull finish is required, nothing further is needed after the descaling process. Polishing with grinding wheels or abrasive belts can produce the smooth finish that is required for sanitation applications. Cold rolling in tandem with annealing can also produce a smooth finish.

Fabrication

Stainless steel can be fabricated by a number of methods. To further shape stainless steel, methods such as press forming, roll forming, press drawing, forging and extrusion are used. Stainless steel can often undergo more annealing, cleaning and machining.

Resistance welding and fusion welding are the most common methods of joining stainless steel. In fusion welding, an electric arc is formed between an electrode and the metal that is being welded. Resistance welding employs both pressure and heat.

Call Us Today

We hope this guide was helpful. For your next custom stainless steel installation, call Western Stainless Solutions: 1300 794 647.