The inter-critical heat affected zone (ICHAZ) appears to be one of the most brittle sections in the welding of high-strength micro-alloy steels (HSLA). Following multiple heating cycles in the temperature range between Ac1 and Ac3, the ICHAZ undergoes a strong loss of toughness and fatigue resistance, mainly caused by the formation of martensite-austenite constituent (MA). The presence of micro-alloying elements in HSLA steels induces variations in the formation of some microstructural constituents, more or less beneficial, which allow to improve the mechanical performance of a welded joint. The behavior in the inter-critical region of a S355 grade steel with 0.1wt% V addition is reported in this paper. Five double-pass welding thermal cycles were simulated using a dilatometer, with the maximum temperature of the secondary peak in the inter-critical area, in the range between 720 °C and 790 °C. The residual austenite dependence on inter-critical temperature is analyzed and related to the hardness behavior.

VANADIUM ALLOYING IN S355 STRUCTURAL STEEL: EFFECT ON RESIDUAL AUSTENITE FORMATION IN WELDED JOINTS HEAT AFFECTED ZONE

Mirabile Gattia D.;
2022-01-01

Abstract

The inter-critical heat affected zone (ICHAZ) appears to be one of the most brittle sections in the welding of high-strength micro-alloy steels (HSLA). Following multiple heating cycles in the temperature range between Ac1 and Ac3, the ICHAZ undergoes a strong loss of toughness and fatigue resistance, mainly caused by the formation of martensite-austenite constituent (MA). The presence of micro-alloying elements in HSLA steels induces variations in the formation of some microstructural constituents, more or less beneficial, which allow to improve the mechanical performance of a welded joint. The behavior in the inter-critical region of a S355 grade steel with 0.1wt% V addition is reported in this paper. Five double-pass welding thermal cycles were simulated using a dilatometer, with the maximum temperature of the secondary peak in the inter-critical area, in the range between 720 °C and 790 °C. The residual austenite dependence on inter-critical temperature is analyzed and related to the hardness behavior.
2022
micro-alloying
residual austenite
vanadium
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/20.500.12079/66692
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