308L can be used to weld 316 stainless steel, but a balance between performance and cost needs to be considered.
1. Feasibility of the welding process
From a process perspective, 308L welding wire can successfully weld 316 stainless steel. Both are austenitic stainless steels and have similar weldability. The low-carbon design of the 308L welding wire (≤0.03%) effectively prevents intergranular corrosion, and the arc is stable with minimal spatter, making it easy to operate.
2. Analysis of compositional differences
| Element | 308L welding wire (%) | 316 stainless steel (%) | Impact differences |
|---|---|---|---|
| Cr | 19.5-22.0 | 16-18 | 308L has a higher chromium content and stronger oxidation resistance. |
| Ni | 9.0-11.0 | 10-14 | 316 stainless steel has a slightly higher nickel content and superior toughness. |
| Mo | ≤0.75 | 2-3 | 316 stainless steel contains molybdenum, which significantly improves its resistance to pitting corrosion. |
| C | ≤0.03 | ≤0.08 (316L≤0.03) | All feature low-carbon design and excellent weldability. |
3. Mechanical Property Matching
The tensile strength and yield strength of both materials are similar (308L has a tensile strength of approximately 580 MPa, and 316 has a tensile strength of approximately 530-1160 MPa), so the welded joint can meet general mechanical strength requirements.
Key defects and risks
1. Significantly reduced corrosion resistance
316 stainless steel contains 2-3% molybdenum, giving it excellent resistance to pitting and crevice corrosion (PREN value 25-30%), while 308L does not contain molybdenum, and the weld metal has a PREN value of only 20-23%. In environments containing chloride ions (marine, chemical, pharmaceutical), the weld seam will become a weak point for corrosion.
2. Not recommended by industry standards
According to the AWS A5.9 standard, ER308L is designed to match 304/304L stainless steel, while the standard matching welding wire for 316 is ER316L or ER316LSi.
Applicable scenarios
1. Scenarios where 308L welding is acceptable:
Temporary welded parts that do not require long-term exposure to corrosive environments
Non-critical structural components with low requirements for corrosion resistance
When cost advantage is a priority, as 308L welding wire is approximately 20-30% cheaper than 316L.
2. Scenarios where 316 welding wire must be used:
Marine equipment and seawater treatment systems
Chemical containers and pharmaceutical pipelines
Food contact equipment
Pressure-bearing components in high-temperature corrosive environments
3. Industry expert recommendations:
Material welding experts unanimously agree that if the service environment requires corrosion resistance, matching 316 series welding wire must be used. 308L should only be used as a temporary emergency solution and not for critical components in long-term service.
