CLASSIFICATION

íníc-NCM12: The nominal composition (wt. %) of weld metal produced by these electrodes is 58 Ni, 21.5 Cr, 9.5 Mo, 3 Fe, and 2Nb plus Ta. Electrodes of this classification are used for welding chromium-nickel-molybdenum austenitic stainless steels to themselves, to duplex ferritic-austenitic stainless steels, to nickel-chromium-molybdenum alloys, and to steel. The ENiCrMo-12 composition is balanced to provide corrosion-resistant welds for use at temperatures below the creep range of highly alloyed austenitic stainless steels. Typical specifications for the chromium-nickel-molybdenum stainless steel base metals are ASTM A240, A167, A182, A249, A276, A312, A358, A473, and A479, most particularly the grade UNS S31254 contained in those specifications. Electrodes through the 3.2 mm size can be used for welding in all positions. Electrodes larger than that can be used only for welding in flat and horizontal positions.

Special Tests

It is recognized that supplementary tests may be required for certain applications. In such cases, tests to determine specific properties such as corrosion resistance, scaling resistance or strength at elevated or cryogenic temperatures may be required. Those tests may be conducted as agreed between the purchaser and supplier.

Corrosion or Scaling Tests

Although welds produced with electrodes in this specification are commonly used in corrosion and heat resisting applications, tests for those properties are not included in the specification. When required for a particular application, tests can be conducted on specimens taken from either a weld pad or a welded joint. Specimens from a joint are suitable for qualifying the welding procedure (for a specific application involving corrosion or oxidation resistance), but not for qualifying the electrode.

Tests on specimens from a joint have the disadvantage of being a combined test of the properties of the weld metal, the heat- affected zone (HAZ), and the unaffected base metal. With them, it is more difficult to obtain reproducible data (when a difference exists in the properties of the metal in the various parts of the specimen). Specimens taken from a joint have the advantage of being able to duplicate the joint design and the welding sequence planned for fabrication.

The heat treatment, surface finish, and marking of the specimens prior to testing should be in accordance with standard practices for tests of similar alloys in the wrought or cast forms. The testing procedures should correspond to

ASTM G4, Standard Guide for Conducting Corrosion Tests in Field Applications.

Welding Considerations

Before welding or heating any nickel-base alloy, the material must be clean. Oil, grease, paint, lubricants, marking pencils, temperature-indicating materials, threading compounds, and other such materials frequently contain sulfur, lead, or silver, which may cause cracking (embrittlement) of the base metal or the weld metal if present during welding or heating.

Electrodes of some of the classifications are used for dissimilar metal welds. When making such welds, it is important to obtain as little dilution as possible from the dissimilar metal member (steel, for example). This can be done by traveling slowly to deposit a thicker bead and to dissipate the energy of the arc against the molten weld metal or the

nickel base metal, rather than the dissimilar metal member.

Most of the electrodes in this specification are intended to be used with DCEP (Direct Current, Electrode Positive) polarity. Some electrodes may be designed to also operate on alternating current which makes them desirable for minimizing arc blow. METAFIL should be consulted to determine if a particular product is designed to be used with alternating current.

CHEMICAL COMPOSITION OF UNDILUTED WELD

Single values are maxima, except where otherwise specified. Rem = remainder.

*Includes incidental cobalt.

ALL-WELD-METAL MECHANICAL PROPERTIES

Preheat and Interpass: 16-150°C

Single values are minima, except where otherwise specified.

Maximum number of fissures permitted in the weld metal on the tension side of each bend specimen.

Number of fissures referred to above is for fissures between 0.4 mm and the length shown in the last column of the table. Those less than 0.4 mm in length and those on the corners of the specimens shall be disregarded.

ELECTRODE SIZE & WELDING CURRENT (DCEP)

WARNING: Safety and health information is available from many sources, including, but not limited to Safety and Health Fact Sheets listed in A11.3, ANSI Z49.1 Safety in Welding, Cutting, and Allied Processes published by the American Welding Society, 8669 Doral Blvd., Suite 130, Doral, FL 33166., and applicable federal and state regulations. The Safety and Health Fact Sheets are revised, and additional sheets added periodically.