Hi All,
Both Type 304 and Type 316 are austenitic stainless. What distinguishes Type 316 from Type 304 is the addition of molybdenum to Type 316 of up to a maximum of 3%, which increases its resistance to corrosion. In the AWS Welding Handbook, "Metals and Their Weldability", Volume Four, Seventh Edition, it states that Types 308, 309, and 316 are austenitic filler metals, and adds that Type 316 electrodes are commonly used for weld overlays. It further states that the deposited weld metal composition should nearly match the base metal composition when welding austenitic stainless to themselves. The recommended filler metal chart shows Type 308 electrodes for Type 304, Type 347 electrodes for Type 304L, and Type 316 electrodes for Type 316, 316L, and 316H.