Effect of Short-Term Low-Temperature Austempering on the Microstructure and Abrasive Wear of Medium-Carbon Low-Alloy Steel

Abstract

Nano-bainitic steels have attracted great attention for good wear resistance. In this research, a medium-carbon low-alloyed steel was austempered at a low temperature close to its martensite-start temperature for various times to obtain mixed microstructure of nano-bainite, martensite and retained austenite. The austempered samples were characterised comprehensively by field-emission SEM and quantitative XRD. Its two-body abrasive wear property was evaluated by sliding on a SiC abrasive disc. The results revealed the formation of initial nano-width carbide-free bainitic ferrite (BF) after austempering by 10 min, whereas the BF size and amount both increased with the austempering time. The austempered samples exhibited wear coefficients lower than the quenched martensitic sample by up to 50%. SEM and TEM observations showed wear mechanisms of micro-cutting and ploughing deformation, including the formation of a nano-laminate top layer and bending deformation in the subsurface multiphase microstructure. The decreased wear loss was attributed to the role of retained austenite in the increased plasticity. Graphic abstract

Pengaruh Variasi Temperatur Proses Austempering Terhadap Mikrostruktur dan Sifat Mekanik Baja Armour

“…Hal tersebut sejalan dengan pembentukan mikrostruktur pada temperatur austempering yang relatif rendah maka fasa yang terbentuk didominasi martensit yang keras pada matriks ferrit. Di sisi lain, pada temperatur austempering yang tinggi memiliki kecenderungan untuk membentuk fasa pearlite yang dapat memiliki nilai kekerasan relatif rendah [10].…”

Enhancing Mechanical Properties of Low Alloy Steel through Novel Molten Bi-Ga Austempering

“…In order to get a more precise microstructure, bainite is better formed at lower temperatures (250-300 °C) and for shorter durations [6]. This enhancement over standard quenching and tempering enhances hardness, wear resistance, and corrosion resistance [2,7]. Luo et al [8] also showed that austenitizing for up to 4 hours was enough to move enough carbon from bainitic ferrite to austenite, which made the balance between strength and ductility better.…”