Austenitic Alloy for High Temperature Equipment and Manufacturing Process

Abstract

The objective of this invention is to obtain an innovative austenitic alloy resistant to oxidation, carburization and creep, especially useful for high temperature applications, such as hydrocarbon pyrolysis furnaces, reformer tubes used in the direct reduction of iron (DRI) process and other equipment that operate under severe temperature and pressure conditions, including an alloy characterized by a high aluminum content and a Cr/Al weight percent ratio≤8.0, which ensures the formation of a protective layer of aluminum oxide (Al2O3), stable and adherent to the surface, instead of a layer of chromium oxide (Cr2O3). The aluminum oxide layer provides protection against oxidation and carburization at temperatures above 1150° C. The alloy composition was formulated to ensure resistance to creep and coke attack, and to provide good weldability, in addition to minimizing the formation of intermetallic phases and carbides, which impair performance at high temperatures compared to conventional and competing alloys. A specific manufacturing process was developed to control the content of impurities and active elements, which are very reactive to oxygen and are very difficult to incorporate, in order to guarantee the quality and compositional uniformity of the alloy.

Dependencies are inferred from the claim text.