An assessment for mechanical and microstructure behavior of dissimilar material welded joint between nuclear grade martensitic P91 and austenitic SS304 L steel

Tensile and impact toughness properties of various regions of dissimilar joints of nuclear grade steels

Hardfacing is done to increase the service life of structural components. Hardfacing is widely done in nuclear and petrochemical industries, mining and sugar refineries. Hardfacing is done on farming equipment to extend their service life as they are prone to impact, abrasion and corrosion. Generally, Ni-base, Co-base and Fe-base alloys are used for hardfacings. Among them, Ni-base alloys are preferred to Co-base and Fe-base alloys as these alloys can retain its hardness even at the elevated temperatures. Colmonoy alloys are predominantly used in nuclear reactor as the dose rate of these alloys is 1/265th that of Co-base alloys. Plasma Transferred Arc (PTA), Gas Tungsten Arc (GTA) and Laser are the major hardfacing processes. The hardfacing process governs the four major aspects of the coating, viz. microstructure, substrate dilution, wear and mechanical properties. This paper provides an in-depth understanding of various research works carried out on Ni alloy hardfacings by different processes on different substrates in those four domains. The outcome of this paper would be beneficial to present and future researchers on Ni alloy hardfacings and also to many hardfacing industries.

Hardfacing studies of Ni alloys: a critical review

Hot wire gas tungsten arc welding (HW-GTAW) process is the one where the filler wire is pre-heated close to its melting point before it is fed in to the arc. The effect of HW-GTAW parameters such as welding current, hot wire current and the wire feed rate during welding of super ASS 304H stainless steel tubes were evaluated in terms of heat input, voltage-current (V-I) characteristics and weld bead characteristics such as bead weight and geometry. The results obtained indicate that for a constant welding current, increasing the hot wire current and wire feed rate provides a stable V-I characteristics and higher bead weight. Further, increasing the hot wire current and wire feed rate also provides better or desired weld pool and hence the bead geometry was described in terms of width, penetration depth, area of fusion and toe angle. By utilising the above knowledge, the tube to tube butt welding of SS 304H material was carried out. It was observed that, the weld joint is qualified as per the quality requirement of ASME: Sec IX standard.

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A Study on Process Characteristics and Performance of Hot Wire Gas Tungsten Arc Welding Process for High Temperature Materials

The effect of post-weld heat treatment (PWHT) time and multiple PWHT on mechanical properties of modified 9Cr-1Mo steel weld joints has been studied using multi-pass tungsten inert gas (TIG) weld joints fabricated from 12.5-mm-thick plates using matching composition ER90S-B9 filler wire. Radiographically qualified weld joints were subjected to single PWHT at 760 °C for different hold times, viz. 1, 3, 4, 8 and 12 h, as also to multiple PWHT cycles of (1 h + 3 h) and (4 h + 4 h) for comparing with single PWHT of 4 h and 8 h, respectively. Transverse-weld tensile strength of the weld joints (as also the base material) decreases marginally with increasing heat treatment duration. In all heat-treated conditions, the Charpy V-notch impact toughness of more than 200 J is obtained for the weld and base materials. Multiple PWHT is found to have no adverse effect on the tensile properties and impact toughness of the weld joint, which has been corroborated by microstructural examination and hardness measurements.

Effect of post-weld heat treatment (PWHT) time and multiple PWHT on mechanical properties of multi-pass TIG weld joints of modified 9Cr-1Mo steel

https://cyberleninka.org/article/n/298895.pdf

An Overview of Welding Aspects and Challenges during Manufacture of Intermediate Heat Exchangers for 500mwe Prototype Fast Breeder Reactor

Results of tensile, hardness and bend tests of modified 9Cr 1Mo steel welds: Comparison between cold wire and hot wire gas tungsten arc welding (GTAW) processes

Prabhat Kumar

Papers

An Overview of Welding Aspects and Challenges during Manufacture of Intermediate Heat Exchangers for 500mwe Prototype Fast Breeder Reactor

Results of tensile, hardness and bend tests of modified 9Cr 1Mo steel welds: Comparison between cold wire and hot wire gas tungsten arc welding (GTAW) processes

Challenges in Manufacture of PFBR Steam Generators

Comparison of Microstructure and Properties of Modified 9Cr-1Mo Welds Produced by Narrow Gap Hot Wire and Cold Wire Gas Tungsten Arc Welding Processes

Assessment of Impact Strength of Welds Produced by Cold Wire and Hot Wire Gas Tungsten Arc Welding (GTAW) Processes