Superior Through‐Thickness Homogeneity of Microstructure and Mechanical Properties of Ultraheavy Steel Plate by Advanced Casting and Quenching Technologies

Abstract

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.