Can you weld 316 with 308?
You can weld 316 with 308 welding rod in terms of weldability but you should not weld with 308 as it will affect the weldment properties of the welding joint.
A welding joint made with 308 welding electrodes for 316 metallurgies will be having low amount of molybdenum. The PREN (Pitting resistance equivalent Number) of 316 is around 25-30% while the PREN of 308 welding metallurgy is only 20- 23%.
What happens if you will 316 with 308 welding rod?
Stainless steel grade 316 contains molybdenum, which enhances its corrosion resistance (especially pitting resistance) capability compared to grade 304/ 308. Welds made using 308L/ 308 welding rod will have reduced amount of corrosion resistance.
In term of welding strength, both 308 and 316 stainless steel have same mechanical properties.
Best Welding rod for 316 stainless steel
The best welding rods for 316 stainless steel welding are austenitic nickel-chromium wire such as ER316L or ER316LSi for TIG & MIG welding. Stick welding (SMAW) of 316 is best welded with E316L-15/16/17 rods. These rods are designed specifically for joining this specific type of stainless steel and gives good weldability.
Related reading: 316 Stainless Steel Welding Guide