Buttering Layers in welding

 What is Buttering Layers in welding?

In some dissimilar alloy joints, a compatible filler alloy electrode is available to weld the two alloys. For instance, welding austenitic stainless steel to a low-alloy steel is not recommended because the higher carbon in the steel will allow chromium carbides to form in the stainless steel. When chromium carbides form, they deplete the chromium and reduce corrosion resistance. A filler metal like 309L contains higher levels of nickel and chromium to compensate.

A weld joint of carbon or low-alloys steel to austenitic stainless steel can include a buttering layer of 309L filler alloy on the carbon steel surface, followed by a 308L filler alloy to bond this to the austenitic stainless steel. Copper can be welded to steel using a nickel buttering alloy layer. Nickel and copper have continuous solid solubility. Nickel additions in steel increase toughness and strength. After the nickel buttering filler alloy is laid down, a steel electrode can be used to complete the weld joint to the steel part.