Stainless steel is one of the most common types of steel used and, as a key metal in fabrication, often needs to be welded. However, there are some common misconceptions about stainless steel, mainly that it cannot be welded or is unsafe to do so.
Stainless steel is best welded by a TIG welder to produce the strongest welds. Although stainless steel retains heat, it’s perfectly possible and safe to weld stainless steel, provided it’s done in a well-ventilated area by a professional with adequate safety gear.
If you want to know more about how welding stainless steel plays into the welding & fabrication industries, then you’re in luck. In this comprehensive blog, we have collated everything you’d need to know about stainless steel welding.
Can Stainless Steel Be Welded?
Yes, stainless steel welding is possible using three techniques, shielded Metal Inert Gas (MIG), Tungsten Inert Gas welded (TIG), or stick welded. TIG welding is the strongest and most common way to weld stainless steel, although each welding method can be used to achieve safe and strong welds with some preparation.
Of the three different types of welding methods, the best method for welding stainless steel is TIG welding. Due to its superior strength, it is the most common technique used for projects in the aerospace, automotive, construction and energy generation industries. It can be time-consuming, challenging, and expensive, but it results in high-quality welds. This procedure entails using one foot and both hands to work the foot pedal.
Is Welding Stainless Steel Difficult?
Welding stainless steel is difficult due to its ability to retain heat efficiently. If the welder applies too much heat, the steel can either distort or warp from the excessive temperature during the cooling process.
It’s also challenging to work on a metal table since it can scratch the surface quickly. It takes experience and a lot of practice to pull off welding stainless steel without damaging the work area. Another challenge is working around all the scratch marks and blemishes in the steel due to the welding process.
What Types of Stainless Steel are Easiest to Weld?
The most common type of stainless steel is Austenitic steel. It’s the easiest to weld, making it the most widely used in standard fabrication and machining shops.
Stainless steel is classified according to its microstructure, chemistry, and reaction to heat. These characteristics influence the steel’s flexibility, strength, and other chemical and physical features.
The hard martensitic stainless steel is another material that’s not as challenging to manage. It’s commonly used in hard facing and other high-wear applications. On the other hand, ferritic stainless steel, a less expensive option, is a popular choice for automotive exhaust components and other consumer products. It’s the least costly among all possibilities, especially since it’s easier to handle.
What Type of Welding is Best for Stainless Steel?
The best type of welding for stainless steel is TIG welding or Tungsten Inert Gas welding. This is because the weld is at a comparatively lower temperature, and the gases used in TIG welding are less likely to cause corrosion or oxidation when welding.
The best welding type for stainless steel depends on the project. Each welding process will yield a different result.
The things that will affect what type of welder you use for stainless steel will include:
- The skill level of the person using the welder
- The thickness of the steel being used
- The total budget for the project
- The amount of time you have to complete the project
- The desired look of the finished product
If the welder is creating a project that needs to be aesthetically pleasing, then tungsten inert weld or TIG is the best option. On the other hand, if efficiency and speed are the priority, then Metal inert Welding (MIG) should be applied.
Can You MIG Weld Stainless Steel?
Yes, stainless steel can be welded with a MIG welder. An arc welding technique, Metal Inert Gas or MIG welding, utilises a heated continuous solid wire electrode. Welders use a welding gun to feed the wire into a weld pool. Shielding gas emitted from the gun to the electrode protects the weld pool from contamination.
The key to welding stainless steel using the MIG method is correctly setting up the welding machine. The welder must ensure that its settings are meant for stainless steel. Teflon wire liners can prevent contamination and provide good wire feed. Stainless steel is known to be resistant to corrosion, but it can be prone to contamination. The MIG method may cause stainless steel to rust when ferrous material enters the weld pool. Exercising utmost care can prevent contamination.
Before starting any project, experienced welders ensure that the MIG torch is in tiptop shape. Most of the time, they use torches larger than the material used to weld regular steel. A giant torch carries higher amperes later and can manage the excessive heat produced by stainless steel. Experienced welders also recommend using steel grinding and cutting discs and stainless steel wire brushes.
A workspace free from steel dust, ferrous oxides, or iron is ideal for avoiding ferrous contamination. Maintaining exceptional cleanliness is vital in achieving a high-quality outcome.
Can You TIG Weld Stainless Steel?
Yes, TIG welding can weld stainless steel and is the preferred method for welding it. TIG welders have a much lower chance of creating rust, oxidation or corrosion on the surface of the stainless steel, and the lower welding temperature reduces the chance of the metal or weld being damaged.
Tungsten Inert Gas or TIG welding is a popular stainless steel welding method because it is versatile, long-lasting, and has high-quality results, making stainless steel one of the many different types of steel that work well with TIG welding. This welding method is best for thin materials since it creates a lower heat input than other methods. Welders keen on TIG use argon gas and mix them with hydrogen, helium, or nitrogen. The required material depends on a project’s specific needs.
A single-sided welding process can increase resistance to corrosion and prevent oxidation. This method creates inert gas protection backing between the exterior and interior welds. When the temperature at the base metal beside the metal reaches a specific temperature, microstructural changes will happen.
These transformations will depend on the alloy content, filler metal joint design, the thickness of the steel, and the skill of the person welding the steel. The main goal of TIG welding is to provide a sturdy joint that’s stronger than the base metal.
Can You Spot Weld Stainless Steel?
Yes, stainless steel can be spot welded. It is a standard method used to connect two thin sheets of metal. The electric current that passes between the metal sheets and the electrodes causes a high resistance within the sheets. It ensures enough heat to melt the metal and fuse them.
The amount of spot welds you can have on stainless steel depends on the material, the strain on the electrodes, and the thickness of the steel. Welding stainless steel in a spot welding machine requires copper-cobalt-beryllium electrodes. These materials have excellent electric conductivity and tensile strength.
Is Welding Stainless Steel Dangerous?
Stainless steel welding can be safe as long as welders exercise the following extra-precautionary measures. Any metal work or construction activity has its own risks, and welding stainless steel is no different.
Ensure proper ventilation – Protecting the respiratory system is one of the most critical aspects of safe welding activity. Stainless steel welding fumes contain Cadmium and Chromium, which can irritate the respiratory system. These fumes can cause breathing difficulties, sore throat, and chest pains if inhaled. Long-term effects include emphysema, kidney damage, or cancer. To prevent respiratory damage, these safety precautions need to be followed:
- Use a powered air-purifying respirator.
- Welders need powered and supplied air respirators if working in a restricted space. However, powered and supplied air respirators are prohibited in Immediately Dangerous to Life or Health atmospheres.
- Filter gas and particles using a powered air respirator. Experts recommend an A1 gas filter and a high-efficiency particulate filter. Welders may need supplied air for welding if the ventilation is limited.
Prepare a Safe Workplace – Before starting any activity, it would be best if welders ensure that their workshop is optimised for safety. Adequate ventilation is a crucial requirement. Installing fume and dust extraction machines can keep the space well-ventilated.
It would also help to maintain the cleanliness of the work area. Metal dust and other contaminants can significantly affect the quality of the finished product.
Wear Proper Protective Gear – It is essential to protect the body and the face from fumes, heat, flying debris, and irritation. The following are the required protective gear typically used in welding.
- Eye and Face Protection – Hand shields, goggles, and welding helmets are essential gear that protects the face and eyes. It can also shield the welder from hot sparks, intense light, radiation, chemical burns, and irritation. A fire-resistant head covering worn under the helmet is an appropriate extra layer of protection.
- Lung Protection – Improper ventilation can damage the lungs, especially if the welder is exposed for long periods. A respirator is must-have protective equipment to shield against toxic fumes and oxides.
- Exposed Skin Protection – Aside from the eyes and face, other exposed parts of the body need protection, too. Flame-resistant aprons and clothing can safeguard the body from burns, radiation, fire, and heat. Welders are also required to wear pants without cuffs and shirts with covered pockets.
- Ear Protection – Earplugs and fire-resistant earmuffs protect against noise and flying sparks.
- Feet and Hand Protection – Rubber-soled safety boots and insulated gloves can protect the feet and hands against heat, burns, fires, and electric shock.
Consumables for Welding Stainless Steel
What Type of Gas Do You Use to Weld Stainless Steel?
Welders use Carbon Dioxide and Argon gases for stainless steel welding. For MIG welding, the usual shielding gas combinations are as follows:
- 98% Argon and 2% Carbon Dioxide or C2
- 95% Argon and 5% Carbon Dioxide or C5
- 95% Argon and 10% Carbon Dioxide or C10
- 95% Argon and 25% Carbon Dioxide
Some welders also use a Tri-mix gas composed of 7.5% Argon, 2.5% Carbon Dioxide, and 90% Helium. The choice of gas mixtures depends on the filler wire and the base metal.
What Filler Do You Use to Weld Stainless Steel?
In most cases, welders match the stainless steel type with the number indicated on the base metal to choose the correct filler for the heat conditions. It is a common practice, especially when using ferritic stainless steel.
On the other hand, welding austenitic stainless steel typically matches a 308 or 308 L label per American Welding Society standards. Welding a carbon steel bracket or valve to stainless steel requires a 309-grade filler metal.
The filler metals meant for austenitic steel were chosen for the following distinct characteristics of the alloys they contain.
- Molybdenum performs well in high-temperature processes and also provides resistance to corrosion.
- Silicon promotes weld pool fluidity.
- Chromium also offers resistance to corrosion.
- Nickel boosts the weld’s toughness.
What Metals Can You Weld to Stainless Steel?
Welding Carbon steel to Grade 304 and grade 316 austenitic stainless steel is possible through MIG or TIG methods. You can weld stainless steel to dissimilar metals with a MIG welder, providing you are using a filler metal with higher ferrite content.
Generally, the ideal material to weld together is those with the same mechanical and chemical composition. However, some projects in the fabricating, manufacturing, and construction industry may find the need to weld dissimilar materials. Welding carbon and stainless steel provide a more cost-effective solution than fabricating something entirely out of stainless steel. Welding stainless steel to carbon steel is also done to provide the corrosion-resistant properties of stainless steel to carbon steel.
What Is Stainless Steel Welding Used For?
Stainless steel welding is used to permanently combine pieces of stainless steel and is done to create food processing and kitchen equipment, architectural panelling, marine equipment, metal art installations, and aerospace and automotive parts.
Stainless steel can be welded to itself or to other dissimilar metals without compromising the strength of the weld or the project. Welding stainless steel to dissimilar metals adds to the corrosion resistance to weld and the project, often found in modern architecture where balustrade posts and railings see stainless steel welded to carbon steel to provide the structural integrity of carbon steel with the finish of stainless steel.
Does Welded Stainless Steel Rust?
Stainless steel may rust in some conditions but not as severe or fast as other steel. Corrosion may occur due to prolonged exposure to grease, saline, moisture, heat, or damaging chemicals.
How Do You Prepare Stainless Steel for Welding?
As a rule of thumb, stainless steel needs to be exceptionally clean before welding. It is also equally essential to ensure the workspace is spic and span to avoid contamination.
What is Passivation for Stainless Steel?
Passivation is a cleaning process that involves cleaning the welds with hydrofluoric acid, “pickling paste,” nitric acid, and other different chemicals. Welders end the welding process with this step not only for aesthetic purposes but also to prevent corrosion.
Can You Use the Same Welder to Weld Stainless Steel and Aluminium?
Aluminium and stainless steel are completely different metals and require different welding set-ups to weld properly and safely. Following a dedicated aluminium welding guide is the best way to choose the right welding set-up for aluminium.
This article is published in good faith and for general informational purposes only. Kanyana Engineering does not make any warranties about the ongoing completeness and reliability of this information. Always seek specific advice on your metal fabrication project to ensure all variables are taken into consideration.
Graham Dawe is the Managing Director and Works Manager of Kanyana Engineering. With decades of experience in the metal fabrication industry, he is dedicated to keeping Kanyana at the forefront of the sector’s technological growth. Looking beyond the process itself to holistic, integrated CAD, CAM and MRP solutions, Graham believes Australian manufacturing has an enduring place on the global stage. In Kanyana Engineering’s state-of-the-art workshop in Mandurah, WA, Graham delivers an exceptional standard of work for commercial, industrial and government clients alike.