Monel alloy 400 has excellent corrosion resistance in many environments, including both reducing and oxidizing conditions. It is particularly resistant to hydrochloric & sulfuric acids, as well as to salt water and other chloride-containing environments. It also has good resistance to stress corrosion cracking and pitting corrosion. Compared to other nickel alloys, Monel alloy 400 has superior corrosion resistance in reducing environments, such as hydrochloric and sulfuric acids, but it may not be as corrosion resistant as other alloys in some oxidizing environments, such as nitric acid or boiling alkaline solutions. However, it is one of the most corrosion resistant nickel alloys available. It is also important to note that the corrosion resistance of Monel alloy 400 may be affected by the presence of impurities or contaminants, as well as by the specific conditions of the environment in which it is used.