Welding Stainless Steel: Methods & Best Practices
Humans have been welding bits of metal and alloys together since the Bronze Age, and welding stainless steel has been prominent since the early 20th century. This involves applying heat, pressure, or both to 2 or more pieces of material to bind them together. An additional material is typically used to create a ‘join’, often referred to as a ‘filler’ or ‘consumable’.
In this blog we will highlight the challenges, methods and best practices involved in welding services such as those that we provide here at Salamander Fabrications.
Stainless Steel Welding Methods
Spot Welding
Also known as resistance welding, this is one of the most common methods of welding stainless steel and many other metal materials. In this process a copper alloy electrode is used in contact with the metal sheet surfaces being worked on. This leads to an electric current passing through them, which applies heat and pressure, melting the material.
As the parts fuse together the electric current is removed but the pressure is maintained, creating a joint. This welding process doesn’t use filler material and has no risk of weld spatter.
The benefits of spot welding stainless steel include:
- Quick transfer of energy to the specified spot
- Efficient use of heat that’s easy to automate
- Suits a wide range of applications and industries
MIG Welding
MIG (metal inert gas) welding is usually most suited to larger or thicker materials. This type of arc welding generates heat via the use of a continuously fed electrical current. This melts the materials so that a solid joint is formed when cooled. A consumable wire acts as both the electrode and the filler.
The benefits of MIG welding stainless steel include:
- Shorter lead times in comparison to TIG welding
- Little to no cleaning or finishing of the welds required
- Low production costs
TIG Welding
TIG (tungsten inert gas) welding is usually most suited to smaller or thinner materials. This approach uses a non-consumable tungsten electrode and a filler is optional. Heat applied to the weld can be controlled via a foot pedal or finger control, increasing precision and minimising the chances of warping.
The benefits of TIG welding stainless steel include:
- Greater control compared to MIG welding
- Really strong welds can be achieved with this method
- Ultimate precision
Robotic MIG Welding
This is also known as gas metal arc welding (GMAW) and essentially involves a robotic welding system rather than a human to carry out the MIG process. The system is fed a filler wire continuously, where a high-temperature electrified tip is used to melt the wire. This is a semi-automatic process that can be operated by a welder remotely.
The benefits of robotic MIG welding stainless steel include:
- Safer process for the human welder
- Consistently high quality results
- Lower production costs
Welding Stainless Steel Challenges and Best Practices
Heat Sensitivity, Warping and Distortion: Heat tends to stay localised to the weld area as stainless steel has low thermal conductivity. This may lead to excessive heat buildup, which can cause warping or distortion.
To avoid this you can:
- use low heat input and fast travel speeds
- allow the material to cool between welds
- use pre-weld and post-weld clamping to control distortion
Maintaining Corrosion Resistance: If welded incorrectly, chromium carbides can form that deplete chromium from the alloy. This causes ‘sensitisation’ which makes the steel more prone to corrosion.
To avoid this you can:
- control the temperature between passes in multi-pass welds
- use filler materials with higher chromium and nickel content
- clean the area thoroughly before and after welding
Avoiding Cracking: Stainless steel is susceptible to both hot and cold cracking. Hot cracking occurs during solidification and cold cracking can happen when the weld has cooled down.
To avoid this you can:
- use a filler material that matches the stainless steel’s properties
- consider pre-heating thicker sections and control cooling rates afterwards
- avoid welding in cold environments
Oxidation and Discoloration: Stainless steel can form an oxide layer when exposed to air during welding. This creates a heat tint that can reduce corrosion resistance.
To avoid this you can:
- use an inert shielding gas like argon
- use shielding gas on the underside of the weld when welding pipes or tubes
- clean or treat the material post-weld
Avoiding Gas Pockets: Gas pockets can sometimes get trapped in the weld, which will weaken a joint.
To avoid this you can:
- clean the welding surface and ensure it is free from oils and moisture
- use the correct shielding gas and maintain consistent gas flow
- check for leaks in your gas supply system
Other Best Practices for Welding Stainless Steel
- Use dedicated tools and equipment to avoid cross-contamination from other materials.
- Use the correct electrode or filler material that matches the stainless steel grade being welded.
- Keep heat input as low as possible/you need to.
- Always ensure proper ventilation to protect against hazardous fumes.
- Maintain a controlled and consistent weld speed to avoid excessive heat buildup.
- Allow the weld to cool slowly and naturally.
- Use pickling paste, mechanical cleaning, or passivation to remove any oxide layers or discoloration and restore corrosion resistance.
- Conduct non-destructive testing (NDT) to ensure weld quality.
Professional Welding Services at Salamander Fabrications
A team of expert welders coupled with a depth of industry-relevant knowledge means we are one of the UK’s most trusted providers of welding services. We have completed countless different interesting stainless steel related projects over the last 50+ years in the business. We look forward to helping you with yours.
All of our welding operators are highly skilled coded welders with experience working with steels, stainless steels, aluminium, and many other metal materials.
Salamander Fabrications Welding Specifications
- EN 15614-1: Specification and qualification of welding procedures for metallic materials. Part 1: Arc and gas welding of steels and arc welding of nickel and nickel alloys.
- EN 15614-2: Specification and qualification of welding procedures for metallic materials. Part 2: Arc welding of aluminium and its alloys.
- EN 9606-1: Qualification testing of welders. Fusion welding – steels.
- EN 9606-2: Qualification test of welders. Fusion welding – aluminium and aluminium alloys.
Contact Our Friendly Sales Team for More Information
If you would like some more information or advice please feel free to contact us, give us a call on 01484 843599 or send an email to sales@salamanderfabs.com. Our friendly sales team will be more than happy to help find the right solution for your stainless steel welding needs.
