Sulfuric acid is one of the most important elementary substances of the chemical industry. There is no stainless steel or even a nickel base alloy available which is suitable over the entire concentration range. This paper will give corrosion data in up to 75 % sulfuric acid at boiling temperature for various commercial grades as well as for some new developmental alloys.
Sulfuric and hydrochloric acids are among the most common chemicals produced.in the process industry. Nickel alloys have been a traditional material of choice. This paper will review the alloys available for this service as well as identify the temperature limits and other conditions that should be considered when selecting an alloy.
The high performance alloy UNS N06058 contains about 21 wt.-% chromium and at least 18.5 wt.-% molybdenum. It is the first member of the Ni-Cr-Mo alloys intentionally strengthened with nitrogen. Based in the combination of its alloying constitutes this alloy is highly resistant to oxidizing as well as to reducing corrosive media. Evidenced by the high Pitting Resistance Equivalent (PRE) number of about 86 the alloy UNS N06058 shows an outstanding resistance to localized corrosion as well.
The objective of this paper is to outline the characteristics of alloy UNS N06058 and therefore to highlight the successful use of it in demanding corrosive applications in the process industry and other sectors.
Main characteristics such as microstructure, mechanical properties and fabrication will be discussed. The very good weldability of alloy UNS N06058 has been verified by the German TÜV1. A matching filler metal, which is officially qualified according to AWS 5.14 (American Welding Society)2, is available. In addition, prior work shows that alloy UNS N06058 can be reliably explosion clad. Furthermore, corrosion resistance determined under laboratory conditions as well as in field studies will be presented not only for the base material but also exemplary on welded and cladded samples. Examples of applications will complete the comprehensive overview of this work.