The Effects of Vanadium on the Parent Plate and Weldment Properties of API 5LX80 Steels
Abstract:
The effects of vanadium, nitrogen and titanium levels and cooling rate through the transformation on the parent plate and weldment properties of laboratory cast, controlled rolled and accelerated cooled API SLX-80 linepipe steels have been investigated. Parent plate yield strengths >600MPa have been achieved by control of processing conditions and chemical composition.
Superior transverse Charpy toughness, (>90J@ -100°C), has also been obtained in steels which contained a small (0.01 % ) titanium addition.
The steels examined all had very fine ferrite grain sizes (2-3μm) and the mechanical properties, particularly the yield strength, have been shown to depend on grain size, substitutional strengthening and precipitation strengthening. In addition, the titanium-treated steels have been shown to contain a lower volume fraction of M-A phase and this reduction has had a significant beneficial influence on the impact properties.
In two-pass welds, in which the second pass was carried out at 3.9kJ/mm, acceptable levels of both weld metal and heat affected zone impact properties, weldment hardness levels and crossweld tensile performance have been achieved. The addition of titanium resulted in refinement of the HAZ microstructure. The levels of weld metal and HAZ toughness have been compared with published information and have been shown to be broadly typical of such steels.
Keywords:
vanadium, pipeline steel.
Author:
J. T. Bowker (1), R. F. Orr (1), G. E. Ruddle (1), P. S. Mitchell (2)
Affiiation
(1) MTL, CANMET, Ottawa, Canada.
(2) anadium International Technical Committee.
PDF:
Source:
35th Mechanical Working and Steel Processing Conference. Vol. 31; Pittsburgh, Pennsylvania; USA; 24-27 Oct. 1993, pp.403-412 (Vanitec Publication - V0693)
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