Grain Refinement and Microstructural Evolution in Cobalt-Saving 18Ni (300) Maraging Steel via Cold Deformation-Cyclic...

Area of Science:

• Materials Science
• Metallurgy
• Mechanical Engineering

Background:

• Traditional processing of Co-saving 18Ni (300) maraging steel faces limitations in enhancing plasticity.
• Improving mechanical properties requires novel processing routes for advanced steel alloys.

Purpose of the Study:

• To develop and evaluate a cold deformation-cyclic solution treatment process for Co-saving 18Ni (300) maraging steel.
• To investigate the effects of multiple solution treatments on microstructure and mechanical behavior.
• To optimize the process for achieving superior strength-plasticity balance.

Main Methods:

• Development of a cold deformation-cyclic solution treatment process.
• Systematic microstructural characterization using techniques like grain size analysis.
• Tensile property testing to evaluate strength and elongation.
• Analysis of retained austenite content and texture evolution.

Main Results:

• A 30% cold deformation followed by three solution treatments (860 °C, 10 min) maximally refined austenite grains (3.3 μm) and martensite structure.
• Uniform equiaxed grains, eliminated texture, and formation of 4.5% retained austenite were observed.
• Optimal strength (1240 MPa, +15.3%) and plasticity (9.93% elongation, +94.3%) were achieved compared to traditional methods.

Conclusions:

• The cold deformation-cyclic solution treatment process is highly effective for improving maraging steel properties.
• Grain refinement and uniform equiaxialization are key mechanisms for enhanced strength and plasticity.
• This methodology offers a viable route for tailoring microstructure and mechanical performance in maraging steels.