New Ni‐Cr‐Mo alloy demonstrates high‐temperature structural stability with resultant increases in corrosion‐resistance and mechanical properties

Abstract

Equipment made of NiCrMo alloys of the Ni 16 Cr 16 Mo W and Ni 22 Cr 16 Mo types is used extensively in the chemical industry, in particular because the corrosion resistance in the as‐welded condition could be improved in recent years by controlling C and Si contents to very low levels. A new type of alloy — Hastelloy Developmental Alloy C‐455 — has high resistance to carbide and intermetallic phase precipitation at high temperatures. By reducing the amount of these phases it has been possible to considerably improve the high temperature properties, the corrosion resistance and the mechanical properties of the alloy. The new material may be exposed to sensitizing range temperatures (550–1090 °C) for a long time without becoming susceptible to corrosion: it is, therefore, readily weldable. Contrary to NiCrMo alloys known so far there are almost no problems when the material is exposed to hydrochloric and sulfuric acids.

Nickel and Nickel Alloys

“…Alloy C-4 offers good corrosion resistance to a wide variety of media, including organic acids and acid chloride solution. Details of alloy C-4 development have been documented [10,18,19]. This alloy has found greater acceptance in European countries than in the United States, in contrast to alloy C-276, which is more widely used and accepted in the United States.…”

The Effect of Alloy Composition on The Dealloying of Ni- and Fe-Based Engineering Alloys in Boiling Caustic Solutions

“…Carbide precipitates in the form M 23 C 6 and M 6 C are the most important precipitates in Ni-Cr-Fe, Ni-Cr-Mo, and stainless steel alloys. [26][27][28][29][30] Titanium carbonitride particles that are not affected by heat treatment may also exist in the microstructure of Ni-Cr-Fe alloys. 31 These precipitates could alter the mechanical properties of Ni-and Fe-based alloys.…”

Corrosion, 1. Electrochemical

“…2.4610) and NiCr21Mo14W (material no. 2.4602), exhibit a considerably reduced susceptibility due to their lower carbon and silicon contents (both < 0.1%); thus, there is no further risk of intergranular corrosion in practical applications [53][54][55][56][57].…”