CLASSIFICATION

ímet-9016B92(H4R) is a low-hydrogen potassium type, 9% Cr–2% W–0.5% Mo–0.20%-V–0.05% Nb electrode designed to provide improved creep strength, toughness, fatigue life, and oxidation & corrosion resistance at elevated temperatures. Due to the higher elevated temperature properties of this alloy, components that are now fabricated from stainless and ferritic steels may be fabricated from a single alloy, eliminating problems associated with dissimilar welds. In addition to the classification requirements in this specification, impact toughness or high-temperature creep strength properties may be determined. Due to the influence of various levels of carbon and niobium, testing must be agreed between the purchaser and supplier.

Thermal treatment of this alloy is critical and must be closely controlled. The temperature at which the microstructure has complete transformation to martensite (Mf) is relatively low. For applications requiring optimum ductility and creep resistance, consideration should be given to allowing the weldment to cool to at least 93°C before PWHT to maximize transformation to martensite. The maximum allowable temperature for PWHT is also critical in that the lower transformation temperature (Ac1) is also comparably low. To ensure proper PWHT results, a restriction on Mn+Ni has been imposed at 1.40 max. The combination of Mn and Ni tends to lower the Ac1 temperature to the point where the PWHT temperature approaches the Ac1, possibly causing partial transformation of the microstructure. By restricting the Mn+Ni, the PWHT temperature will be sufficiently below the Ac1 to avoid this partial transformation.

Since all Cr-Mo electrodes produce weld metal which will harden in still air, both preheat and PWHT are required for most applications. No minimum notch toughness requirements have been established for any of the Cr-Mo electrode classifications. While it is possible to obtain Cr-Mo electrodes with minimum toughness values at ambient temperatures down to 0°C, specific values and testing may be agreed, if desired based on job requirements.

Storage and Drying Conditions: Not recommended | Ambient temperature (For R-Class)

Hydrogen can have adverse effects on welds in some steels under certain conditions. One source of this hydrogen is moisture in the electrode coverings. For this reason, the proper storage, treatment, and handling of electrodes are necessary.

Holding Ovens: 125°C–150°C Drying Conditions: 250°C–425°C

CHEMICAL COMPOSITION OF UNDILUTED WELD

Single values are maxima, except where specified otherwise. Mn + Ni shall be 1.40% max.

ALL-WELD-METAL MECHANICAL PROPERTIES

Preheat and Interpass :200-315°C | Post weld Heat Treatment : 760±15°C for 2 Hour(s) The temperature shall be raised at the rate of 85°C to 280°C per hour and allowed to cool at a rate not greater than 200°C per hour, and may be removed from the furnace when the temperature of the furnace has reached 300°C and allowed to cool in still air.

Single values are minimal.

Limit of Moisture Content, % by weight max: 0.15 max (Reconditioned) | NS (As Exposed) for H4 version Diffusible Hydrogen Content Average, Maximum, mL(H2)/100 g Deposited Metal: 4.00

Welding Considerations

Preheat and interpass minimum temperatures also have a significant effect on the strength levels attained with certain low-alloy steel weld metals. These weld metals are affected by rapid cooling rates which tend to produce more martensitic or bainitic microstructures. These microstructures will often exhibit higher yield and tensile strengths with a decrease in ductility.

The cooling rate can be retarded by utilizing a higher preheat and interpass temperature. The preheat and interpass temperature ranges given herein are adequate for the preparation of the test assemblies.

However, in actual production, users are encouraged to test their own procedures to verify that they have selected preheat and interpass temperatures which will produce desirable results in production.

SIZES & CURRENT CONDITIONS (AC or DCEP)

NOTE: H4 R variant is available for supply on request.

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.