Microstructure and Mechanical Performance Correlation in a Pulsed Laser Welded IN792 DS Alloy.

Area of Science:

• Materials Science and Engineering
• Mechanical Engineering
• Metallurgy

Background:

• Pulsed laser welding of IN792 DS joints presents challenges in accurately assessing mechanical performance and microstructure.
• Existing standard codes have limitations in accounting for local bulk elastoplastic behavior and residual stress.
• Microscopic and metallurgical methods may fail to detect the heat-affected zone (HAZ) width.

Purpose of the Study:

• To investigate the mechanical performance of pulsed laser butt-welded IN792 DS joints and its relation to microstructure.
• To introduce and validate a new ISE-free (rate-derived) hardness parameter (H_R) for improved mechanical assessment.
• To estimate the composition of phases within the fused zone using an iterative statistical deconvolution scheme.

Main Methods:

• Grid nanoindentation was employed to analyze the mechanical properties.
• A novel rate-derived hardness parameter (H_R) was introduced to incorporate residual stress effects.
• An iterative statistical deconvolution scheme utilized indentation parameter spectra to estimate phase composition.

Main Results:

• The fused zone (FZ) comprised approximately 54% γ-matrix and 43% ultrafine hard second phases.
• Deconvoluted mechanical performance values (E_IT, H_IT, H_R) were determined for the FZ.
• A correlation was established between estimated phases and local mechanical performance, considering cooling rate effects.

Conclusions:

• The new H_R parameter offers a more comprehensive assessment of mechanical performance in welded joints.
• The deconvolution method accurately estimated phase composition within the FZ with a 5% tolerance.
• Further validation is recommended for diverse sample geometries, materials, and joint configurations.