Effects of Titanium and Vanadium on the Spring Corrosion Fatigue

Abstract

Nao YOSHIHARA, Nobuhiko IBARAKI, Mitsuhiro SUGIYAMA, Akira TANGE 0.4 C-Ti-V steel can enhance the suspension spring design stress comparing the common steel grades such as SAE 9260 or 9254 and has been increasingly applied to automobiles. Titanium and vanadium addition to this steel grade have the two significant features for improving spring corrosion fatigue property. Titanium and vanadium system precipitations lead to the fine austenite grain size with their pinning action. Furthermore tianium and vanadium system precipitations can trap the diffusible hydrogen in the steel during corrosion fatigue. Hydrogen trapping effect and austenite grain size refining can contribute to delay the fatigue crack propagation under the corrosion pit. It is cleared that titanimum has the larger effect than vanadium on the corrosion fatigue property, hydrogen embrittlement, and fracture toughness from this study and there is room for optimizing titanium and vanadium contents.

Effect of Cu Addition on Delayed Fracture Resistance of Low Carbon Steel for 1 470 MPa Grade Electric Resistance Welded Tube

“…The effects of titanium and vanadium carbide on delayed fracture resistance were evaluated as a function of hydrogen trap site. [16][17][18][19][20][21][22][23][24][25][26][27][28][29][30] Whether this function enhances or suppresses the delayed fracture depends on the condition. For example, vanadium carbide increases the critical hydrogen content, 20,28) but it also increases the absorbed hydrogen.…”

“…20,22,24,25) The effects of the substitutional solute atom have also been examined. [29][30][31][32][33][34] Siraga et al 31,32) clarified that the concentrated Ni on surface suppresses diffusible hydrogen permeation from FIP solution and improves the delayed fracture property. They also clarified the effects of Si on delayed fracture property through microstructure morphology.…”

“…[16][17][18][19][20][21][22][23][24][25][26][27][28][29][30][31][32][33][34][35] Compared with high strength bolts, high strength thin-wall as-rolled ERW tubes have a different precondition: lower carbon equivalent, lower applied stress, smaller stress concentration, and different exposed environment. As the result, there might be differences in the limits for practical application of bolts versus thin-wall tubes.…”