Designing quadplex (four-phase) microstructures in an ultrahigh carbon steel

作者：Zhang H^*; Ponge D; Raabe D

来源：Materials Science and Engineering A-Structural Materials Properties Microstructure and Processing, 2014, 612: 46-53.

DOI：10.1016/j.msea.2014.06.023

• Steel
• Quadplex microstructure
• Thermomechanical processing
• Strain
• Electron backscatter diffraction (EBSD)

Here we present an approach to design a ferrite-based quadplex microstructure (ferrite/martensite/ carbide/austenite) using a lean alloyed Mn-Si-Cr-Al ultrahigh carbon steel. The material has 1500 MPa tensile strength and 11% elongation. The thermomechanical processing includes two main steps, namely, first, the formation of a ferrite plus carbide duplex microstructure by warm rolling below Ae(1); and second, annealing just above Ae(1) for a short time (similar to 20 min). The quadplex microstructure consists of 57 vol% ultrafine ferrite (mean grain size similar to 1.5 mu m), 29 vol% martensite, 12 vol% spherical carbide and 2 vol% austenite. Fracture analysis after tensile deformation reveals a mixed ductile and brittle failure mode without necking. Scanning electron microscopy (SEM), electron backscatter diffraction (EBSD) and dilatometry tests were conducted to map the microstructure characteristics and the contribution of each phase to the overall deformation.

• 出版日期2014-8-26