Effect of Solution Treatment on the Microstructure and Mechanical Properties of IN718 Alloy

Powder Characterisation, Microstructure, and Mechanical Property Evolution of IN625 and IN718 During Selective Laser Melting and Heat Treatment

“…as its primary strengthening element is the Nb: (AL, Ti) ratio (Jinhui et al, 2017a;Quist et al, 1971;Radavich, 2004;Slama et al, 1997). Where the ratio is higher the alloys for γ'' as is the case for both IN625 and IN718.…”

“…I give consent for this thesis to be made available online in the University's Open Access Repository and for inter-library loan, and for the title and summary to be made available to outside organisations. 3 -Graph illustrating the improvement in stress rupture life as correct heat treatments are applied to control the δ content of the material to the correct level (Jinhui et al, 2017b) .13 Figure 4 -Improvement of creep life of wrought IN718 material due to serration of grain boundaries. A) shows the primary and secondary creep phase of both materials during the first 300 h of testing, showing little difference in behaviour.…”

“…Maximum Ni and Fe content for IN625 and IN718 are specified as a balance of the rest of the elements, the value of the maximum content was calculated assuming the minimum content of all other elements. (Aircraft Materials, n.d.;Clavel & Pineau, 1978;Jinhui et al, 2017a;C.-M. Kuo et al, 2009;Special Metals Corporation, 2004). Despite the compositional differences, as the main alloying elements in both alloys are the same, the precipitate phases which can form in either alloy are the same, so they will be discussed together in later sections.…”

“…These areas allow deformation and relaxation of stress, typically at the grain boundaries, until weak precipitates or boundaries nucleate cracks leading to failure (S. Li et al, 1994). This can be detrimental to both room and elevated temperature yield strength although not ultimate tensile strength (Saied Azadian et al, 2004;Brooks & Bridges, 1988;Jinhui et al, 2017a;S. Li et al, 1994).…”

“…Figure 3 -Graph illustrating the improvement in stress rupture life as correct heat treatments are applied to control the δ content of the material to the correct level (Jinhui et al, 2017b) Another reported benefit of δ precipitates within the material highlights the importance of the distribution of δ phase. Where δ is present at grain boundaries it provides Zener pinning of the boundaries, this helps to control and restrict grain growth during solution treatment, allowing for fine microstructure to be achieved (Saied Azadian et al, 2004;Geng et al, 1997;Reed, 2006a).…”