Critical and subcritical cracking of high-strength wires obtained by cold-drawing of pearlitic and duplex stainless steels

Abstract

Cold-drawing is a strain-hardening process that allows the elastic limit and the tensile strength of pearlitic steel wires to be raised up to levels necessary for prestressing concrete. The strong orientation that the steel microstructure undergoes in the drawing direction determines the micro-mechanisms and resistance of this wire types to critical and subcritical cracking, respectively activated by service loads per se or combined with environmental actions and other singular service circumstances. The paper approaches the comparison of damage micro-mechanisms to critical cracking and hydrogen-assisted subcritical cracking of three cold-drawn high-strength steels, one of pearlitic type and the other two of duplex stainless steels with different molybdenum content. The results are based on experimental data resulting from critical and subcritical cracking tests and subsequent micro- and macro-fractographic analysis of the damage micro-mechanisms. The influence of microstructure on the behavior of the three steel wires is determined on the basis of the analogies and differences between them.