Can you use 308 or 316 stainless rods to weld carbon steel to stainless steel if you do not have 309?

Yes, you can use 308 or 316 stainless rods to weld carbon steel to stainless steel, although it's not the ideal choice. The 309 filler rod is specifically designed for dissimilar metals, providing better compatibility and mechanical properties. Using 308 or 316 may result in a weaker joint and potentially lead to issues like cracking or corrosion, so it’s essential to consider the application and service environment of the weld. Proper preparation and technique can help mitigate some challenges when using these rods.