Dynamic Flow Stress Behavior of Hypo-Eutectoid Ferrite-Pearlite Steels Under Rapid Heating

Area of Science:

• Materials Science
• Mechanical Engineering
• Metallurgy

Background:

• Machining involves high strain rates and rapid heating, leading to potential non-typical microstructures.
• Understanding material behavior under these extreme conditions is crucial for process optimization and predicting performance.

Purpose of the Study:

• To investigate the dynamic stress-strain behavior of carbon steels under rapid heating conditions.
• To analyze the influence of short heating times on microstructural evolution and mechanical properties.

Main Methods:

• Dynamic stress-strain measurements were performed on AISI 1018, 1045, and 1075 carbon steels.
• Samples were subjected to rapid heating (under 4 s) up to 1000 °C.

Main Results:

• Mechanical behavior was characterized in four regions: thermal softening, dynamic strain aging, pearlite decomposition, and ferrite-austenite thermal softening.
• Results aligned with literature up to ~700 °C, indicating limited effect of short heating times below A1.
• Above A1, significant divergence was observed due to limited diffusion, including an inversion of carbon content's effect on flow stress.

Conclusions:

• Rapid heating significantly influences steel behavior above the pearlite decomposition temperature (A1).
• Limited time for diffusion processes under rapid heating alters phase transformations and mechanical responses.
• The effect of carbon content on flow stress above A1 is inverted compared to longer heating time studies.