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Cold-drawn prestressing steel wires are susceptible to hydrogen embrittlement (HE) in aggressive environments, and the residual stress-strain states generated in wires by the drawing process play the key role there. Hence, the alterations of the stress-strain fields due to the specific features of the drawing procedure affect the serviceability of wires under HE. On the basis of performed numerical simulations of the process of cold drawing with the use of different drawing dies, the paper addresses the effect of the inlet angle of the die on the residual stress-strain fields in the wires. We also deduce their consequences for the hydrogenation of wires and their susceptibility to HE. The reduction of the die inlet angle is shown to be beneficial for the performance of wires. [ABSTRACT FROM AUTHOR]

Abstract: Hydrogen embrittlement (HE) of prestressing steel is a major technological problem in damage tolerance and structural integrity of structures in harsh environments, it being strongly influenced by residual stresses and plastic strains after cold-drawing. This paper calculates the distributions of such variables (mechanical approach) and later the stress-and-strain assisted diffusion of hydrogen (chemical approach) in a real manufacturing process by multi-step cold drawing. Results confirm the relevant role of plastic strain in HE of prestressing steel and thus the necessity of considering it in hydrogen diffusion calculations, because stress-only assisted diffusion leads to dramatic (and non conservative) underestimation of the hydrogen content. [Copyright &y& Elsevier]

Abstract: Cold drawn wires of eutectoid pearlitic steel are widely used for prestressing concrete structures that usually work in harsh environments, so that stress corrosion cracking of prestressing steel is a problem of major technological concern. In this paper a previous model developed by the authors is applied to analyse the influence of the residual stress-and-strain profiles after cold drawing on the hydrogen embrittlement susceptibility of prestressing steel wires. Numerical results show the relevant role of both residual stress and strain field in hydrogen diffusion in this material [Copyright &y& Elsevier]

Hydrogen degradation represents a problem of major technological concern in the structural integrity of prestressed concrete structures in which cold-drawn wires are the main structural component and can suffer the deleterious effect of hydrogen, with the subsequent risk of catastrophic failure. This paper presents an innovative numerical analysis of hydrogen degradation of cold-drawn prestressing steel wires, focused on {he two relevant variables influencing the phenomenon of hydrogen transport by diffusion in the metal: residual stresses generated by manufacture and plastic strains after cold work. To achieve this goal. two real (industrial) drawing processes are analyzed with two main differences, namely, the reduction of cross-sectional area performed at the first drawing stage and the number of drawing steps used in the whole process. Generated results prove the importance of an adequate design of the cold-drawing process with regard to the residual stress-and-strain field and its relevant role in hydrogen diffusion in the wires, as well as its possible consequences for hydrogen degradation and. thus, for catastrophic failure. [ABSTRACT FROM AUTHOR]

We analyze the influence of the distributions of residual stresses and strains formed after the surface treatment of cold-drawn steel wires used as the reinforcement of prestressed reinforced concrete on the susceptibility of these wires to hydrogen embrittlement characterized by the time to fracture in the tests carried out according to the regulations of the FIP (Fédération Internationale de la Précontrainte). A computational model is proposed for the prediction of the durability of wires in corrosive hydrogenated media. In the model, the accumulation of hydrogen in potential sites of fracture as a result of diffusion under the influence of stresses and plastic strains is analyzed and a criterion of critical concentration of hydrogen specifying the time of local fracture depending on the stress-strain state is formulated. The enables us to predict the influence of specific features of the distributions of residual stresses and plastic strains after various types of thermal treatment on the durability of wires under the conditions of hydrogen embrittlement. [ABSTRACT FROM AUTHOR]

This paper analyzes the effects of crack tip plastic strains and compressive residual stresses, created by fatigue pre-cracking, on environmentally assisted cracking of pearlitic steel subjected to localized anodic dissolution and hydrogen assisted fracture. In both situations, cyclic crack tip plasticity improves the behaviour of the steel. In the respective cases, the effects are supposed to be due to accelerated local anodic dissolution of the cyclic plastic zone (producing chemical crack blunting) or to the delay of hydrogen entry into the metal caused by residual compressive stresses, thus increasing the fracture load in aggressive environment. [ABSTRACT FROM AUTHOR]