Effect of Post Processing Heat Treatment Routes on Microstructure and Mechanical Property Evolution of Haynes 282 Ni-Based Superalloy Fabricated with Selective Laser Melting (SLM)

Anagh Deshpande,Keng Hsu,Subrata Deb Nath,Sundar Atre

doi:10.3390/met10050629

Abstract

Selective laser melting (SLM) is one of the most widely used additive manufacturing technologies. Fabricating nickel-based superalloys with SLM has garnered significant interest from the industry and the research community alike due to the excellent high temperature properties and thermal stability exhibited by the alloys. Haynes-282 alloy, a γ′-phase strengthened Ni-based superalloy, has shown good high temperature mechanical properties comparable to alloys like R-41, Waspaloy, and 263 alloy but with better fabricability. A study and comparison of the effect of different heat-treatment routes on microstructure and mechanical property evolution of Haynes-282 fabricated with SLM is lacking in the literature. Hence, in this manuscript, a thorough investigation of microstructure and mechanical properties after a three-step heat treatment and hot isostatic pressing (HIP) has been conducted. In-situ heat-treatment experiments were conducted in a transmission electron microscopy (TEM) to study γ′ precipitate evolution. γ′ precipitation was found to start at 950 °C during in-situ heat-treatment. Insights from the in-situ heat-treatment were used to decide the aging heat-treatment for the alloy. The three-step heat-treatment was found to increase yield strength (YS) and ultimate tensile strength (UTS). HIP process enabled γ′ precipitation and recrystallization of grains of the as-printed samples in one single step.

Highlights

Nickel-based superalloys have excellent high temperature properties and thermal stability
Size distribution of the Haynes-282 powder used in all the experimental runs and the chemical composition of the powder as received from the manufacturer have been given in Tables 1 and 2, respectively
Elongated shape of dendrites in one melt-pool is due to cross-section cut parallel to the dendrites in that melt-pool versus the polygonal shape in the other melt-pool, which is due to the cross-section cut perpendicular to the length of the dendrites in that melt-pool

Summary

Introduction

Nickel-based superalloys have excellent high temperature properties and thermal stability. They are widely used for high temperature applications like gas turbines, space vehicles, nuclear reactors, heat-exchangers, etc. For such low production run applications, additive manufacturing technologies have several advantages over conventional manufacturing methods. Inconel 718 [1,2], Inconel 625 [3,4], Hastealloy-X [5], Nimonic-263 [6], Waspaloy [7], and several other Ni-based superalloys have been fabricated with SLM and the post manufacturing mechanical properties and microstructure have been studied in detail.

Methods

Results

Conclusion