Stainless steels form a large and important group of engineering materials that have been used in a variety of industries. Welding is a manufacturing process that has been in development for more than a century and has resulted in a large number of specifications, recommended practices and manuals that provide insight into the techniques and precautions necessary to weld these materials.In general, stainless steels are considered to be weldable materials, but there are rules that must be followed to ensure that they will be free of defects and the results will be as expected for the service to which they will be designated. when these rules are not followed, problems during fabrication or service are very frequent. often these problems are associated with inadequate control of the weld microstructure and associated properties, or the use of welding procedures that are not suitable for the material and its chemical composition.