AWS WHC-4.05:2010

Stainless and Heat Resistant Steels
Scope : Stainless steels are alloy steels with a nominal chromium (Cr) content of at least 11 weight percent (wt %), with or without other alloy additions.1, 2 The oxidation and corrosion resistance of these alloy steels are attributed to the presence of a passive chromium-rich oxide film on the surface. The chromium-rich oxide can be damaged, but will quickly reform if oxygen is available. When exposed to conditions that damage the passive oxide film, stainless steels are subject to corrosive attack. The rate at which a stainless steel develops a passive film in the atmosphere depends on its chromium content. Polished stainless steels remain bright and tarnish-free under most atmospheric conditions. Exposure to elevated temperatures increases the thickness of the oxide film. An example of the use of stainless steel combining art with utility is shown on the title page of this chapter: the stainless steel-clad BP Bridge and the Jay Pritzker Pavillion in the Millennium Park, Chicago. The bridge, a first-prize winner in national competition, is an architectural work of art, provides conveyance to the 120 ft high pavilion, and is a sound barrier to street noises.