WHAT IS STAINLESS STEEL?

WHAT IS STAINLESS STEEL?

Stainless steel is an iron and chromium alloy. While stainless must contain at least 10.5% chromium, the exact components and ratios will vary based on the grade requested and the intended use of the steel.

HOW STAINLESS STEEL IS MADE

The exact process for a grade of stainless steel will differ in the later stages. How a grade of steel is shaped, worked and finished plays a significant role in determining how it looks and performs.

Before you can create a deliverable steel product, you must first create the molten alloy.

Because of this most steel grades share common starting steps.

Step 1: Melting

Manufacturing stainless steel starts with melting scrap metals and additives in an electric arc furnace (EAF). Using high-power electrodes, the EAF heats the metals over the course of many hours to create a molten, fluid mixture.

As stainless steel is 100% recyclable, many stainless orders contain as much as 60% recycled steel. This helps to not only control costs but reduce environmental impact.

Exact temperatures will vary based on the grade of steel created.

Step 2: Removing Carbon Content

Carbon helps to increase the hardness and strength of iron. However, too much carbon can create problems—such as carbide precipitation during welding.

Before casting molten stainless steel, calibration and reduction of carbon content to the proper level is essential.

There are two ways foundries control carbon content.

The first is through Argon Oxygen Decarburization (AOD). Injecting an argon gas mixture into the molten steel reduces carbon content with minimal loss of other essential elements.

The other method used is Vacuum Oxygen Decarburization (VOD). In this method, molten steel is transferred to another chamber where oxygen is injected into the steel while heat is applied. A vacuum then removes vented gases from the chamber, further reducing carbon content.

Both methods offer precise control of carbon content to ensure a proper mixture and exact characteristics in the final stainless steel product.

Step 3: Tuning

After reducing carbon, a final balancing and homogenization of temperature and chemistry occurs. This ensures that the metal meets requirements for its intended grade and that the steel’s composition is consistent throughout the batch.

Samples are tested and analyzed. Adjustments are then made until the mixture meets the required standard.

Step 4: Forming or Casting

With the molten steel created, the foundry must now create the primitive shape used to cool and work the steel. The exact shape and dimensions will depend on the final product.