Ni-based superalloy Haynes 282 is a prime candidate for advanced power generation systems due to its superior fabricability, weldability, and high-temperature performance. Additive manufacturing offers potential cost and time savings for gas turbine components. Wire-arc direct energy deposition can create large components but often requires post-processing treatments, such as hot isostatic pressing (HIP), to address porosity. This study explores a low heat-input, high deposition rate GMAW process to achieve fully dense Haynes 282 without HIP. Twenty-one blocks were deposited, varying travel and wire feed speeds. Initial analysis (visual inspection, microstructural examination, and CT) revealed the impact of build parameters on internal porosity and defects. Scanning electron microscopy provided insights into structural heterogeneity and microstructural properties.

The power industry has been faced with continued challenges around decarbonization and additive manufacturing (AM) has recently seen increased use over the last decade. The use of AM has led to significant design changes in components to improve the overall efficiency of gas turbines and more recently, hot-section components have been fabricated using AM nickel-base superalloys, which have shown substantial benefits. This paper will discuss and summarize extensive studies led by EPRI in a novel AM nickel-base superalloy (ABD·900-AM). A comprehensive high temperature creep testing study including >67,000 hours of creep data concluded that ABD-900AM shows improved properties compared to similar ~35% volume fraction gamma prime strengthened nickel-base superalloys fabricated using additive methods. Several different creep mechanisms were identified and various factors influencing high temperature behavior, such as grain size, orientation, processing method, heat treatment, carbide structure, chemistry and porosity were explored. Additional studies on the printability, recyclability of powder, wide range of process parameters and several other factors have also been studied and results are summarized. A summary on the alloy -by-design approach and accelerated material acceptance of ABD-900AM through extensive testing and characterization is further discussed. Numerous field studies and examples of field use cases in ABD-900AM are also evaluated to showcase industry adoption of ABD-900AM.

NAC International Inc. (NAC) is providing transportable storage canisters (TSCs) to Central Plateau Cleanup Company CPCCo) for long term dry storage of capsulized radioactive waste at the Hanford Site in Richland, WA. The TSC consists of 316/316L stainless-steel components welded to form a cylindrical canister that acts as a confinement boundary for the payload. The heat affected zones of the welded areas are most susceptible to Chloride Induced Stress Corrosion Cracking (CISCC), that may limit the life of the TSC. To mitigate CISCC during the anticipated 300-year storage period, an overcoating is applied to the heat affected zones of all external TSC fabrication welds, referred to as Cold Spray. This paper will discuss the purpose, development, and application of Cold Spray to the CPCCo TSCs. Cold Spray is a process whereby metal powder particles are deposited upon a substrate by means of ballistic impingement via a high-velocity stream of gas, resulting in a uniform deposition with minimal porosity and high bond strength. Temperatures are below the melting thresholds of many engineering materials enabling a large variety of application uses. NAC developed a process for Cold Spray application onto the 316/316L stainless-steel TSCs to serve as a CISCC protective/mitigative coating for its canister products. Testing during development arrived at nickel as the deposited coating material and nitrogen as the gas vehicle, along with a set of various application parameters. The qualified process was implemented onto the CPCCo TSCs. Prior to application, the equipment and process are validated via coupons that are sprayed and then tested to meet requirements for adhesion strength (ASTM C633) and porosity (ASTM E2109). After successful coupon testing, Cold Spray is performed on the external TSC fabrication welds, to include heat affected zones. Acceptance testing of the resulting deposition is performed via visual inspection.

The measurement of damage from high temperature solid particle erosion (HTSPE) can be a lengthy process within the laboratory with many lab-based systems requiring sequential heat and cooling of the test piece to enable mass and/or scar volume measurements to be made ex situ. Over the last few years a new lab-based system has been in development at the National Physical Laboratory which has the ability to measure the mass and volume change of eroded samples in situ without the need to cool the sample. Results have previously been shown demonstrating the in situ mass measurement, more recently the in situ volume measurement capability has been added and used to evaluate the erosion performance of additively manufactured materials. Selective laser melting (SLM) is an advanced manufacturing method which is growing in popularity and application. It offers the ability to manufacture low volume complex parts and has been used in rapid prototyping. As the technique has developed there is increasing interest to take advantage of the ability to manufacture complex parts in one piece, which in some case can be more cost and time effective than traditional manufacturing routes. For all the benefits of SLM there are some constraints on the process, these include porosity and defects in the materials such as ‘kissing bonds’, surface roughness, trapped powder and microstructural variation. These features of the processing route may have implications for component performance such as strength, fatigue resistance wear and erosion. To investigate this further SLM IN718 has been used to evaluate factors such as surface roughness, microstructure and morphology on the erosion performance as measured in situ and compared with conventional produced wrought IN718 material.