In this study, we obtained different morphology and size of epsilon carbides (ɛ-carbides) via low temperature tempering of 0.32 wt-% C low alloy wear resistance steel. The objective is to elucidate the determining role of size and morphology of carbides on mechanical properties and three-body impact wear resistance. The formation of small needle-like ɛ-carbides was responsible for increase in yield strength, low temperature impact toughness and three-body impact wear resistance. However, when the ɛ-carbides were large and rod-like, hardness, toughness and three-body impact wear resistance were significantly reduced. The wear mechanism of steel containing needle-like ɛ-carbides primarily involved plastic deformation associated with fatigue and small degree of abrasive wear and furrow, while steels containing rod-like ɛ-carbides were predominantly characterised by furrow.
Keeping through‐thickness homogeneity of mechanical properties has been a great challenge for producing heavy gauge steel plates. Herein, a superior homogeneity of microstructure and hence strength and toughness achieved in a quenched and tempered (QT) 210 mm‐thickness steel plate produced by advanced electroslag remelting casting and roller quenching (ESR–RQ) technologies are reported. Some comparisons are made with a QT 178 mm steel plate produced by conventional mold casting and immersion quenching in the water tank (MC‐IQ). The martensite of the as‐quenched ESR–RQ steel is distributed homogeneously across the thickness with a fraction of 39% at the 1/2 thickness, remarkable higher 34% than that of MC‐IQ steel. ESR–RQ steel appears excellent comprehensive mechanical properties even for the as‐quenched samples, as well as QT samples. Comparing with the MC‐IQ steel, the Charpy impact energy at −60 °C is 150 J (278%) higher for the samples tempered at 650 °C, and the yield strength is 137 MPa (18%) higher for the samples tempered at 600 °C than those of MC‐IQ steel, respectively. The considerable improvement can be attributed to homogeneous through‐thickness microstructures, including refined prior austenite grains, effective grain size, and carbide precipitates.
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