Influence of solution treatment on microstructure and mechanical properties of duplex stainless steel prepared by powder metallurgy technique

This study investigates the influence of solution treatment on the microstructure, mechanical properties of
powder metallurgy duplex stainless steels (DSS) developed from 316 L and 430 L powders. The sintered DSS
samples were annealed at two distinct temperatures of 1150 ◦C and 1250 ◦C, followed by water quenching.
Comprehensive characterization, including optical microscopy, scanning electron microscopy (SEM), and energy
dispersive spectroscopy (EDS), was conducted to evaluate phase distribution and elemental composition. Mechanical
properties were assessed through tensile strength, hardness, and elongation tests. The findings reveal
that solution treatment enhances densification, particularly at higher annealing temperatures, promoting a homogenous
austenite-ferrite phase distribution. For DSS sintered in partial vacuum and solution treated at 1250
◦C, densification reached 7.72 g/cm³ (98.1 % of theoretical density). Significant improvements in tensile strength
(up to 824 MPa) and yield strength (up to 438 MPa) were observed. DSS sintered in partial vacuum exhibited
superior densification and mechanical performance compared to those sintered in hydrogen. This is due to the
minimized oxidation, enhanced diffusion kinetics, and reduced residual porosity achieved in partial vacuum
conditions, which collectively improve densification and mechanical stability. These enhanced properties make
the treated DSS suitable for applications in marine environments, chemical processing equipment, oil and gas
pipelines, and structural components in corrosive or high-stress conditions. The optimized balance between
strength and ductility also positions these materials as viable candidates for high-performance automotive and
aerospace components.