Different Types of Steel for Welding Purposes
Mar 15, 2023
Welding is a fabrication process that involves fusing two pieces of metal using heat, pressure or a combination of both. Metal fabricators have access to several types of steel for welding, with each steel type offering different characteristics and attributes based on your project’s requirements. These differences will also impact how the steel is welded together.
Arc welding, friction welding, electron beam welding, laser welding, and resistance welding are all common welding processes. Each welding method has advantages and disadvantages that fabricators can use for different projects and various welding joints and techniques to create fabricated steel products.
Continue reading for more information on the world of welding steel, including answers to frequently asked questions such as can you weld galvanised steel? That, and so much more down below.
Common Steel Welding Processes
The exact science behind welding is quite complex, but in simple terms, welding is a fabrication process that fuses two components using heat, pressure or a combination of both. The joint between these two components is called a weldment.
There are a number of different welding processes.
Arc Welding: Metals are welded using the heat generated by an electric arc. This steel welding includes some of the most common welding processes like metal inert gas (MIG) Welding, tungsten inert gas (TIG) welding, shielded metal arc welding (“SMAW” or Stick) Welding and oxy-acetylene welders (“gas” or “oxyfuel”) welding.
Friction Welding: Using the heat generated from mechanical friction to create a bond between two components as they cool.
Electron Beam Welding: A beam of high-speed electrons fusing materials.
Laser Welding: Concentrated heat from a laser that combines elements.
Resistance Welding: The two types of resistance welding are spot welding (where the heat between two electrodes is applied to a small area to weld materials) and seam welding where rotating wheels deliver heat for a continuous leak-free weld.
The welding joint design specifies the sort of weld technique required by the fabricator to satisfy project requirements. For example, T-joints require a fillet weld; butt joints require a groove weld; lap joints require fillet welds, and corner joints can be fillet or groove welds.
Let’s have a look at some of the common welding joints.
Butt Joint: A link between two pieces’ ends or edges that meet at an angle of 135° to 180° in the joint area.
T-Joint: A link between a part’s edge or end and its face when the angle between the two is greater than 5° and does not exceed 90°.
Corner Joint: A joint between the ends/edges of two components at an angle greater than 30° but less than 135° in the joint area.
Edge Joint: Two pieces joined together, where the edges in the joint area form an angle with one another of 0 to 30°.
Cruciform Joint: Welding two flat plates or two bars at a straight angle along the same axis.
Lap Joint: A welding joint between two overlapping pieces at an angle of 0° to 5°.
Structural Steel Welding Techniques
Different welds are described by their cross-sectional shape. Joints are combined with welds to make weld joints.
Fillet Weld: A joint between two pieces of metal perpendicular to each other or at an angle is known as a Fillet Weld.
Stitch Weld: Also known as intermittent welding, stitch welding is a connection made by starting a weld, continuing it for a portion of the joint’s length, ending it, and then starting the weld again along the joint a certain distance from the last one.
Slot Weld: A joint between two overlapping components.
Plug Weld: Joining two pieces of metal together by filling a hole in one element with filler metal.
The welding method isn’t the only factor that influences the strength of a weld. The material or metals used, the weld length and size, the filler used, and even the welder’s expertise all play a role.
Common Types of Steel Used in Welding
Each metal and metal alloy reacts to heat differently, significantly impacting how it can be manipulated and fabricated. When heated, metals expand and soften, resulting in various uses and applications. Metal also reacts differently to different sorts of welding processes.
The most common types of steel used in welding are carbon steel, stainless steel, alloy steel, aluminium steel, tool steel, cast iron and galvanised steel.
As one of the most commonly used materials for welding, carbon steel is a low-cost material with excellent welding properties, including good tensile strength and weldability. However, carbon steel is more susceptible to rust and corrosion, which can weaken the weld joint over time. Carbon steel is also prone to cracking during the welding process, negatively impacting the quality of the final product.
For welding projects, thanks to its excellent resistance to corrosion and rust, stainless steel is widely used in the food and beverage industry and marine and coastal environments where exposure to saltwater is a concern.
Stainless steel is more expensive than carbon steel and can be challenging to work with, making it a less suitable choice for low-budget welding projects.
There are several types of stainless steel, each with a different grade, which describes its quality, robustness, and temperature resistance. There’s also a number to represent the composition of the stainless steel and the amount of chromium and nickel in the product.
Combining iron and other elements, such as carbon, manganese, nickel, chromium, and more, gives alloy steel improved strength and toughness, excellent corrosion resistance, and heat resistance. Like stainless steel, there are various alloy steel types available.
Used in aerospace and automotive applications where weight and durability are critical, Aluminium steel is favoured for its superb corrosion resistance, lightweight, and good heat dissipation.
Known for its excellent hardness and wear resistance, tool steel is an ideal choice for applications where high performance is required, like manufacturing, cutting and shaping instruments found in industrial equipment.
Commonly used to manufacture pipes and fittings, cast iron is known for its excellent strength and durability, making it an ideal choice for applications requiring high performance.
Regularly used for modern steel frame buildings, galvanised steel is regular steel that’s covered in a zinc coating for added rust resistance. However, to weld galvanised steel, this zinc coating must be removed first.
Important Properties of Steel Used in Welding
Each type of steel has unique properties that make it suitable for different welding purposes. Some of these properties include:
- Melting Point: The temperature at which the steel becomes liquid.
- Strength: What is the breaking point of a metal?
- Toughness/ Ductility: How the metal reacts to bending, stretching.
- Electrical Conductivity: How readily the metal conducts electricity.
- Corrosion Resistance: How resistant metal is to corrosion or rust in harsh environments. Some types of steel, such as stainless steel, are more corrosion-resistant than others.
- Weldability: How easy it is to weld a type of style, dependent on steel composition and properties. Typically, the higher the carbon concentration, the more difficult it is to weld the steel.
- Cost: Some types of steel are more expensive than others.
Steel Welding Questions
How do I know what type of steel I need for my project?
The higher the carbon concentration, the more difficult it is to weld the steel. For room-temperature welding, low-carbon mild steel is the industry standard.
Can you weld galvanised steel?
Yes, Galvanised Steel can be joined together using the most common welding techniques.
Can you weld aluminium to steel?
Yes, aluminium alloys can be joined to steel using methods like adhesive bonding, mechanical fasteners, or brazing. However, welding is recommended when higher structural integrity is required.
Can you weld stainless steel?
Yes, Stainless steel can be welded using any arc welding process.