ER308LSi vs ER309LSi vs 316LSi
For welding stainless steels each grade needs to be welded with matching weld chemistry and mechanical properties.
Most welders see different stainless welding wires with similar names and get confused. Some of the most common wires for welding stainless steel are:
- ER-308 LSi
- ER-309 LSi
- ER-316 LSi
In summary, ER308Lsi is used for welding grade 304 stainless steel, and ER309LSi is used for welding stainless steel to mild steel-carbon steel-low alloy steel. ER316LSi is used for 316L stainless steel welding.
Let’s see what the difference between these wires for welding of stainless steel from each other is. To do this, consider the chemical composition of each of the wires and analyze the effect of each chemical element on weldability and quality.
The chemical elements contained in the wire are indicated by the following letters:
- “C” – Carbon. Denoted by the letter “C”
- “Si” – silicon. Denoted by the letter “Si”
- “Mn” – manganese. Denoted by the letter “Mn”
- “Cr” – chrome. Denoted by the letter “Cr”
- “Ni” – nickel. Denoted by the letter “Ni”
- “Cu” – copper. Denoted by the letter “DCu”
- “Mo” – molybdenum. Denoted by the letter “Mo”
Let’s analyze how these elements affect the quality of the seam.
It is the main element that makes stainless steel stainless. Chromium contributes to the formation of a protective oxide film that protects steel from corrosion.
On the one hand, chromium increases the strength, toughness, fluidity and malleability of the metal.
On the other hand, the high content of chromium (similar to carbon) entails the formation of a fragile structure in the transition zones and complicates the welding process, but, with the correct selection of welding modes and proper observance of the technological process, practically does not affect weldability.
The addition of this element leads to the refining of grain and increases the ductility of steels. Weldability is practically not affected as nickel is readily weldable.
On the one hand, it increases strength characteristics, increases hardness, heat resistance, bearing capacity under loads and high temperatures.
On the other hand, it complicates welding, greatly increases hardness, and decreases weldability.
When welding with ER-308 LSi, ER-309 LSi, and ER-316 LSi wires, the weld made with ER-316 LSi wire will have the greatest strength and impact resistance.
On the other hand, due to the presence of Molybdenum in this wire, welding will be more difficult than welding with wires 308 LSi and 309 LSi.
Also, a weld seam welded with ER-309 LSi wire will be more corrosion resistant, because this wire contains the greatest amount of chromium and molybdenum.
The most fine-grained structure will be welded with ER-309 LSi and ER-316 LSi wires.