Heat treatment of welded 13%Cr-4%Ni martensitic stainless steels for sour service

Journal Article · Sat Jul 01 04:00:00 EDT 1995 · Welding Journal

OSTI ID:89687

Gooch, T G ^[1]

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1. TWI, Cambridge (United Kingdom). Materials Dept.

For many years, the petroleum industry has employed martensitic stainless steels for wellhead and valve applications, and increasing use has been made of 13%Cr-4%Ni alloys. This material type was originally developed as a cast alloy (e.g., ASTM A487/A487M-89a Grade CA6NM). The combination of a low-carbon content and the addition of 3.5 to 4.5% nickel produces a fine, lath martensite structure which, after a tempering heat treatment, can exhibit superior mechanical properties. Thus, CA6NM and its forged variant ASTM A182/A182M-91 F6NM find application for production fluids containing CO{sub 2} and H{sub 2}S environments, particularly when hardening occurs, as is the case with fusion welds. Sensitivity to sulfide SCC increases at high material hardness levels, and the NACE MR0175 standard limits 13%Cr-4%Ni alloys to HRC 23 maximum for sour service. Attainment of such a hardness level requires careful consideration of tempering procedure. In this paper, the roles of welding procedure, material composition and postweld heat treatment are examined in relation to producing the minimum hardness levels in the weld zone.

• OSTI ID: 89687
• Journal Information: Welding Journal, Journal Name: Welding Journal Journal Issue: 7 Vol. 74; ISSN 0043-2296; ISSN WEJUA3
• Country of Publication: United States
• Language: English

Related Subjects

02 PETROLEUM
36 MATERIALS SCIENCE
CHEMICAL COMPOSITION
CHROMIUM-NICKEL STEELS
EXPERIMENTAL DATA
FIELD PRODUCTION EQUIPMENT
GAS METAL-ARC WELDING
HARDNESS
HEAT AFFECTED ZONE
HEAT TREATMENTS
MICROSTRUCTURE
OIL WELLS
SHIELDED METAL-ARC WELDING
SOUR CRUDES
WELDED JOINTS