Common Stainless Steel Welding Methods and Frequently Asked Questions

What is a Stainless Steel Weld Joint?

 

A stainless steel, carbon steel, or alloy steel product is joined to another product using welding rods during production or construction. The seam where the welding rods connect the products is called a weld joint, also known as a weld seam.

 

 

 

Common Stainless Steel Welding Methods

 

The most common welding method for stainless steel is manual welding (MMA), followed by metal inert gas welding (MIG/MAG) and tungsten inert gas welding (TIG).

 

1. Manual Welding (MMA):

Manual welding is a very common and easy-to-use welding method. The arc length is adjusted by hand, depending on the size of the gap between the welding rod and the workpiece. The welding rod also acts as the filler material in the weld, acting as the arc carrier.

This welding method is simple and can be used to weld almost all materials. It is well-suited for outdoor use and even works underwater.

 

2. MIG/MAG Welding:

This is an automated gas-shielded arc welding method. In this method, an arc is burned between the current-carrying wire and the workpiece under the shielding of a protective gas. The machine-fed wire acts as the welding electrode, melting under its own arc. Due to the versatility and specific advantages of MIG/MAG welding, it remains the most widely used welding method in the world. It is suitable for steel, non-alloy steel, low-alloy steel, and high-alloy based materials. This makes it an ideal welding method for both production and repair.

 

3. TIG Welding:

An arc is generated between a refractory tungsten electric arc wire and the workpiece. The shielding gas used here is pure argon, and the fed welding wire is uncharged. The welding wire can be fed manually or mechanically. There are also some specific applications where wire feeding is not required. The material being welded determines whether direct current (DC) or alternating current (AC) is used. When using DC, the tungsten electric arc wire is set to the negative electrode. Because of its deep penetration capability, it is suitable for various types of steel, but it does not have any "cleaning effect" on the weld pool.

The main advantage of TIG welding is its ability to weld a wide range of materials.

 

Common Questions

 

1. What should be noted before welding?

Pre-welding cleaning: The purpose of cleaning is to remove the oxide film and oil stains from the surface of the workpiece. This is an important measure to prevent porosity and slag inclusions. Regardless of the welding method, the weld joint should be cleaned thoroughly, free of oil, water, etc. This will reduce the occurrence of welding defects.

 

2. What should be noted after welding?

After welding stainless steel, post-treatment is required, such as cleaning, protection, and anti-oxidation.

(1) Cleaning: After welding, black, yellow, and blue oxide scale will appear on the weld bead. It needs to be cleaned. Yunqing brand weld spot cleaning paste can remove the oxide scale and also passivate it, while maintaining the original color of the stainless steel.

(2) Protection: This involves forming a transparent hard film on the surface, which can isolate the stainless steel from air, water, and other contaminants and corrosion.

 

3. Why is rust prone to occur at the weld joint?

It is normal for stainless steel welds to rust on both sides. It is not that the stainless steel itself is rusting. If it comes into contact with water, the particles in the water will be absorbed by both sides of the weld and form false rust. You can clean it with pickling paste or polish it.