Morphology change of retained austenite during austempering of carbide-free bainitic steel

作者：Hofer Christina; Winkelhofer Florian; Clemens Helmut; Primig Sophie

来源：Materials Science and Engineering A-Structural Materials Properties Microstructure and Processing, 2016, 664: 236-246.

DOI：10.1016/j.msea.2016.04.005

• Mechanical characterization
• Phase transformation
• Bainite
• Austenite
• Electron microscopy

A change in the mechanical properties of a carbide-free bainitic steel was observed during prolonged holding at austempering temperature after termination of the bainitic transformation. To determine the origin of the property change, the microstructure was investigated by correlative electron microscopy. Although the retained austenite content remains the same during prolonged holding, its morphology changes from thin films separating the individual bainitic sub-units to a more globular structure. Since films of austenite contain a higher C concentration, the blocky austenite becomes gradually enriched in C during this morphology change. The more homogeneous distribution of the C after prolonged austempering leads to higher deformability as a result of a more pronounced TRIP effect.

• 出版日期2016-5-10