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    Volume 11, Issue 2 (June 2021)

    Special Issue Paper

    Microstructural and Mechanical Characterization of 1.6-mm-Thick Nimonic-75 Superalloy Welds

    (Received 22 October 2020; accepted 2 April 2021)

    Published Online: 02 June 2021

    CODEN: MPCACD

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    Abstract

    Gas tungsten arc welding (GTAW) and electron beam welding (EBW) studies on thin Nimonic-75 sheets of 1.6-mm thickness have been carried out using butt-weld configuration. Manual GTAW was done using Inconel-718 filler wire with a two-pass welding and EBW was done by autogenous welding. The strength of both the weldments at ambient temperature is found to be marginally (~4%) higher than the base metal. Marginally higher strength in the case of GTAW joints was observed at ambient temperature and is attributed to the use of Inconel-718 filler wire, where the additional alloying elements (niobium, aluminum, molybdenum) and their contents in the weldment contribute to increase in strength. The microstructure of the fusion zone in EBW reveals a needle-shaped/acicular structure with fine dendrites, whereas the dendrites are coarser in the case of GTAW welds. At elevated temperatures (600°C–700°C), the strength of GTAW is similar to the base metal. However, EBW coupon exhibited higher strength (~20–45%) than GTAW coupon, indicating the beneficial role of faster heating/cooling in EBW leading to acicular microstructure.

    Author Information:

    Gupta, R. K.
    Foundry Technology Division, Materials and Mechanical Entity, Vikram Sarabhai Space Centre, Trivandrum,

    Anil Kumar, V.
    Materials Processing Activities Division, Materials and Mechanical Entity, Vikram Sarabhai Space Centre, Trivandrum,

    Kumar, Ravi Ranjan
    Materials and Manufacturing Entity, Liquid Propulsion Systems Centre, Trivandrum,

    Vivek, R.
    Foundry Technology Division, Materials and Mechanical Entity, Vikram Sarabhai Space Centre, Trivandrum,

    Venkitakrishnan, P. V.
    Capacity Building Programme Office, Indian Space Research Organization, Bangalore,


    Stock #: MPC20200155

    ISSN:2379-1365

    DOI: 10.1520/MPC20200155

    Author
    Title Microstructural and Mechanical Characterization of 1.6-mm-Thick Nimonic-75 Superalloy Welds
    Symposium ,
    Committee B02