Dissimilar JointsIt is often necessary to join stainless steel to carbon steel, alloy steel, or different stainless steel. It may sometimes be required to weld stainless steel to copper alloys, aluminium alloys, or cast iron. There are different types of stainless steel, ferritic, martensitic, austenitic, and duplex, each responding differently to welding. Austenitic stainless steel is the type most frequently involved in dissimilar joints and the article concentrates on this type. All types of stainless steel may be welded to carbon and alloy steels using special high alloy Cr-Ni-Mo or Ni alloy consumables, using most fusion welding processes. Welding different stainless steels to each other is generally not too difficult but when selecting a consumable it is advisable to consult the Schaeffler, or other, phase diagram to calculate weld metal composition and structure. To weld stainless steel to cast iron would require a procedure involving buttering of the cast iron with a high nickel alloy consumable before fusion welding to the stainless steel. Joining stainless steels to nickel alloys may be achieved with most processes and use of a high nickel alloy consumable, the type chosen depending on the alloys to be welded together. Aluminium bronze fillers may be used to fusion weld austenitic stainless to some copper alloys but otherwise complicated procedures involving buttering of each component is necessary. Joining aluminium to stainless steel by fusion welding is not recommended but friction and other non-fusion techniques may give acceptable results.
|
