| Abstract Scope |
Rapid thermal processing (RTP) of steels has emerged as a lower cost, higher throughput alternative to conventional quench-and-temper processing while achieving comparable mechanical properties. RTP utilizes rapid, non-equilibrium heating rates and short soak times to limit carbide dissolution and carbon diffusion, resulting in heterogeneous carbon distributions after quenching. However, the influence of RTP microstructures on corrosion resistance remains largely unknown. AISI 4140, AISI 4340, and AISI 420 were chosen for these tests. A Gleeble 3500 was used to investigate varying peak temperatures (with thermal gradients) on single samples resulting in large datasets of final microstructures. Microstructural characterization including optical microscopy, XRD, and nanoindentation identified phases, microstructures, and properties. Open corrosion potential and potentiodynamic polarization were used to evaluate corrosion behavior. SEM and EDS identified corrosion mechanisms and quantified elemental composition changes, to examine relationships between microstructure, elemental distribution, and corrosion resistance. |