A high molybdenum stainless steel and its resistance to chloride environments in the welded condition

Conference · Fri Jan 01 04:00:00 EST 1988

OSTI ID:5485793

Coppolecchia, V D; Jasner, M; Rockel, M B

Highly alloyed stainless steels, such as 1925 hMo UNS N08925 with 6 percent molybdenum, are finding widespread use in high chloride cooling water and process environments. This alloy has good general corrosion resistance to a variety of chloride environments but it's main attraction is excellent resistance to all forms of localized corrosion. In aggressive chloride environments weldments are generally the area of concern with regard to localized corrosion. Temperature-time-sensitization diagrams are presented that demonstrate the resistance of 1925 hMo weldments to intergranular attack. Immersion tests in 10% ferric chloride substantiate that autogenous tube welds, also have excellent pitting resistance. Various filler metals are compared both electrochemically and in immersion tests. These comparisons reveal that an overalloyed filler metal is required to achieve pitting and crevice corrosion resistance equal or better than that of the base metal. Alloy 625 (UNS NO6625) has been selected. Constant extension rate tests in boiling 62% calcium chloride reveal that 1925 hMo weldments are immune to stress corrosion cracking in this environment which virtually guarantees absence of SCC in seawater regardless of temperature as well as in most commercial chemical environments.

• OSTI ID: 5485793
• Report Number(s): CONF-880314--
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360105* -- Metals & Alloys-- Corrosion & Erosion
ALLOYS
CHEMICAL REACTIONS
CHLORIDES
CHLORINE COMPOUNDS
CORROSION
CORROSION RESISTANCE
CORROSION RESISTANT ALLOYS
CORROSIVE EFFECTS
HALIDES
HALOGEN COMPOUNDS
HIGH ALLOY STEELS
IRON ALLOYS
IRON BASE ALLOYS
JOINTS
MOLYBDENUM ALLOYS
STAINLESS STEELS
STEELS
STRESS CORROSION
WELDED JOINTS