Steel Scrap to Tube : How it's Made

What goes into the steel making process?

The steel making process can be overwhelming at first, and with focus on producing a superior product let's break down what happens to create the steel we depend on to meet and exceed our customers designed needs.

There are a few key things to know:

The steel industry has been green for decades, making significant efforts to limit environmental pollution. So, the process uses steel scrap, sourced from other industries, to create new steel. The scrap is delivered to melting mill facilities. With over 150 different classifications of scrap, there many variations to consider.

Different combinations of elements and finishes can drastically change the steel's final specifications. Creating the desired strength, durability, and workability needed to transform scrap metal materials into hardworking steel components.

What Types of Steel Can Be Made?

There are many types of steel. To create a steel "ready for any purpose," mills must combine the right concoction of elements into the mix.

Carbon Steel:

There are several types of carbon steel.

• Low carbon steels (up to 0.3% carbon)
• Medium carbon steels (0.3–0.6% carbon)
• High carbon steels (more than 0.6% carbon)

Alloy Steel:

Alloy steels add additional alloying elements like nickel, copper, chromium, and/or aluminum.

Stainless Steel:

Stainless steels key elements include chromium, nickel, carbon, manganese, silicon, phosphorus, sulfur and nitrogen. These elements work to provide a corrosion resistant product.

Tool Steel:

They are often made with elements such as tungsten, molybdenum, cobalt, and vanadium. This elemental combination creates an extremely hard material that suits the tools needs.

What is the Process to make a Long Bar Product?

Considering how to utilize all 150 classifications of scrap, the steel scrap is delivered the melting mill facility. From here, it follows a specific process to ready it for use.

1. Scrap is strategically dumped into scrap buckets.
2. Lime is added to create slag. (Slag is a complex solution of silicates and oxides that solidifies upon cooling helping to remove impurities)
3. The scrap is dumped into an Electric Arc Furnace (EAF)
4. The metal is heated to 3,000 degrees with the following actions helping to create the correct mix, before being transferred to a shaping machine called a strand caster.

Ladle Injection:

Ladle injection injects specific materials into the ladle of molten steel. This process helps the steel to have desired metallurgic effects. For example, lime and iron oxide can be injected for the dephosphorization of hot metal. The injected materials react with the molten steel. This leads to changes in its chemical composition and properties.

Stirring:

Stirring is a critical process in steelmaking. It efficiently helps achieve the desired states of chemical composition and temperature. Stirring plays a significant role in creating a homogenous mixture. Stirring can be achieved through various methods, including electromagnetic stirring and argon bubbling.

Degassing:

Degassing happens after the molten steel has left the furnace. However, it must be before they're shaped into ingots or put into a continuous caster. Degassing helps eliminate dissolved gasses. Hydrogen and nitrogen are common remnants that can affect the steels performance. This process can also dissolve carbon to increase ductility. Another benefit is that it promotes preferential oxidation of dissolved carbon when refining stainless steel grades.

The vacuum degassing process improves the economics of high-quality steel production. It allows for a less expensive smelting process. It accomplishes this with a shortened smelting cycle and reduced consumption of alloying and deoxidant additives.

Killing Steel: 

This added process allows the creation of oxides that will for the most part float into the slag for removal. Using aluminum and silicon, the affect is to remove gases causing bubbles as the steel cools controlling the recrystallization process and final steel texture.

Slag Removal:

Slag removal happens at various stages during the melt to refinery process. Effectively the impurities are skimmed off the top of the molten metal as the prior steps, through various methods, have pushed impurities to the top for removal.

Argon Gas Shielded Pour:

Argon gas is an inert gas that doesn't react with the atmosphere, acting as a shield around the molten flowing metal. The premise is to protect molten metal from absorbing hydrogen or allowing oxidation at this critical stage.

All metal production is subject to each producers’ individual processes. This information is a general guideline.

What happens when the molten steel mixture is ready?

Some mills have a machine called a strand caster. This machine takes the molten steel and turns it into a clean bar or billet.

At other mills, the molten metal is bottom poured into molds. These molds create the foundation for ingots. This process specializes in creating extremely clean steel. It can also protect from any unwanted steel splashing, which improves surface quality.

This semi-finished steel is now ready for added operations transforming metal into finished raw pipe, tube, and bar using additional machinery and efficient handling equipment. This is where they will undergo additional treatments and processing that helps the steel perform its intended purpose. The quality and strength our customers rely upon.