Vanadium Additions in New Ultra High Strength and Ductility Steels
Kinetic thermodynamic modeling has been used to optimise the process parameters for microalloying high Mn austenitic TWIP cold strips with Vanadium and Nitrogen to promote an intense precipitation of sub 10 nm intragranular V(C,N) particles during the continuous annealing step. The yield strength increase is 500 MPa / % wt. added V. A further interest lies in the amelioration of hydrogen induced delayed fracture (DF) in regions of cold formed parts with critically high residual tensile stresses. The beneficial macroscopic effect on DF is clearly demonstrated; however the physical mechanism governing the interaction between Vanadium and mobile hydrogen is still the subject of investigation.
TWIP, high Mn, austenite, vanadium microalloying, residual stress, delayed fracture.
SCOTT Colin, CUGY Philippe
ArcelorMittal Research, Voie Romaine BP30320, 57283 Maizières-lès-Metz, France
2009 International Symposium on Automobile Steel” (ISAS'09), Dalian, China, 6-8 Sep. 2009, pp.211-221