Comparative Evaluation of Properties of a Traditional Quenched and Tempered Steel and a New, Microaloyed Bainitic Steel as well as Processing Concepts for Forged Components

摘要

A key benefit of bainitic steels is cost reduction for heat treatment in comparison to traditionally quenched and tempered steels due to absence of one heat treatment step. Nevertheless, new alloying concepts are necessary to ensure success of bainitic microstructures for massive parts. Therefore, the innovative microalloyed bainitic steel 12CrMnMoV7-5 mod, which features a new alloying concept, was subjected to controlled cooling from forging temperature to obtain a bainitic microstructure. All investigations of properties and microstructure were done in comparison to a conventionally quenched and tempered steel 42CrMo4. The aim of this research project was to verify the capability of the microalloyed bainitic steel 12CrMnMoV7-5 mod for forged parts which have to endure cyclic loading. Investigations comprised mechanical properties including static and cyclic fracture mechanics as well as fatigue behavior of smooth and notched specimens. The microstructure-properties correlation was examined by visible-light microscopy (VLM), scanning electron microscopy (SEM) and Electron Back Scatter Diffraction -method (EBSD).