ATI 216Cb? Alloy, a New Mo-Bearing Lean Austenitic Stainless Steel

摘要

During the past few years, volatility in the costs of raw materials, such as nickel and molybdenum, has led to instability in the price of stainless steels. To reduce this volatility, many users of austenitic stainless steels have switched to grades containing lower amounts of these more costly elements. For example, in many applications Type 304 has been replaced by ferritic grades or lower-nickel austenitic alloys such as Type 201. However, there has not been a lean austenitic stainless steel alternative for Mo-bearing grades such as Types 316, 316L, or 316Ti. Recently, ATI Allegheny Ludlum developed a proprietary Mobearing lean austenitic stainless steel that provides an economical substitute for the 316 family of stainless steels. This alloy, known as ATI 216Cb? alloy (UNS S21640), has less Ni and Mo than Type 316, and is stabilized with a small addition of niobium (columbium), which improves its resistance to sensitization. UNS S21640 has been developed primarily as a strip product aimed at replacing Type 316Ti in elevated-temperature applications such as automotive flexible connectors and residential chimney liners. However, as shown by the data presented in this paper, S21640 is also suitable as a lean replacement for other grades, such as Types 316 and 316L, in many applications. The mechanical properties and corrosion resistance of S21640 will be presented and compared to those of higher-alloyed grades. The purpose of this paper is to help users of Type 316 or similar alloys decide if switching to S21640 is appropriate for their end-use applications.