Design of a double aging treatment for the improvement of mechanical and microstructural properties of pulse micro-plasma arc welded alloy 718

• Published in: Journal of materials science 2021-08, Vol.56 (23), p.13400-13415
• Main Authors: Sahu, A. K., Bag, S.
• Format: Article
• Language: English
• Subjects: Aging; Aging (metallurgy); Alloying elements; Alloys; Analysis; Characterization and Evaluation of Materials; Chemical precipitation; Chemistry and Materials Science; Classical Mechanics; Crystallography and Scattering Methods; Gamma-double prime phase (crystals); Gamma-prime phase (crystals); Grain boundaries; Hardness; High temperature; Impact analysis; Intermetallic compounds; Intermetallic phases; Materials Science; Mechanical properties; Metals & Corrosion; Morphology; Nickel base alloys; Plasma arc welding; Polymer Sciences; Precipitation heat treatment; Solid Mechanics; Solution heat treatment; Specialty metals industry; Strengthening; Superalloys; Temperature; Tensile strength; Welded joints
• ISSN: 0022-2461; 1573-4803
• DOI: 10.1007/s10853-021-06121-8

The effect of post-weld solution along with different double aging treatments on precipitation of various strengthening phases in Alloy 718 weld is carried out in the current assessment. The formation of intermetallic phases in the weld zone deteriorates the mechanical properties and quality of the weld joint. The high-temperature solution treatment at 1165 °C/1 h has dissolved the intermetallic phases and makes a suitable quantity of alloying elements accessible for precipitation of the strengthening phases. To analyze the impact of aging temperature and holding time on δ , γ' and γ" phase precipitation, four different heat treatment paths are designed. The heat treatment holding time is reduced by 53% on the welded component by applying a higher aging temperature compared to the conventional standard aging temperatures. The variation in aging temperature and holding time followed by solution treatment changes the platelet morphology of the δ phase to needle shape in the grain boundary. Significant enhancement in the tensile strength (21%) and weld hardness (121%) is witnessed due to duplex aging treatment compared to as-welded condition. The XRD analysis confirms the precipitation of γ' and γ'' strengthening phases inside the grain and δ particles in the grain boundaries. Graphical abstract