Effects of Q&P Processing Conditions on Austenite Carbon Enrichment Studied by In Situ High-Energy X-ray Diffraction Experiments

Metals

Frédéric Danoix¹  Guillaume Geandier²  Sébastien Yves Pierre Allain²  Mohamed Gouné³  Jean-Christophe Hell⁴  Michel Soler⁴ 

[1] Groupe de Physique des Matériaux, UMR 6634, Normandie University, UNIVROUEN, INSA Rouen, CNRS, 76801 Rouen, France;Institut Jean Lamour, UMR CNRS-UL 7198, 54011 Nancy, France;Institut de Chimie de la Matière Condensée de Bordeaux, UPR 9048, 33608 Pessac, France;Maizières Automotive Products, Arcelormittal Maizières Research SA, 57283 Maizières les Metz, France;

关键词: steel;    martensite;    bainite;    Q&;    P;    synchrotron;    HEXRD;    TRIP;   

DOI  :  10.3390/met7070232

来源: DOAJ

【 摘 要 】

We report the first ultra-fast time-resolved quantitative information on the quenching and partitioning process of conventional high-strength steel by an in situ high-energy X-ray diffraction (HEXRD) experiment. The time and temperature evolutions of phase fractions, their carbon content, and internal stresses were determined and discussed for different process parameters. It is shown that the austenite-to-martensite transformation below the martensite start temperature Ms is followed by a stage of fast carbon enrichment in austenite during isothermal holding at both 400 and 450 °C. The analysis proposed supports the concurrent bainite transformation and carbon diffusion from martensite to austenite as the main mechanisms of this enrichment. Furthermore, we give evidence that high hydrostatic tensile stresses in austenite are produced during the final quenching, and must be taken into account for the estimation of the carbon content in austenite. Finally, a large amount of carbon is shown to be trapped in the microstructure.

【 授权许可】

Unknown