Effect of Hot Mill Scale on Hydrogen Embrittlement of High Strength Steels for Pre-Stressed Concrete Structures

Abstract

Abstract:The presence of a conductive layers of hot-formed oxide on the surface of bars for pre or post-compressing structures can promote localized attacks as a function of pH. The aggressive local environment in the occluded cells inside localized attacks has as consequence the possibility of initiation of stress corrosion cracking. In this paper, the stress corrosion cracking behavior of high strength steels proposed for tendons was studied by means of Constant Load (CL) tests and Slow Strain Rate (SSR) tests. Critical ranges of pH for cracking were verified. The promoting role of localized attack was confirmed. Further, electrochemical tests were performed on bars in as received surface conditions, in order to evaluate pitting initiation. The adverse effect of mill scale was recognized.

Mechanical Behavior of High-Strength, Low-Alloy Steels

“…This is well documented in the paper written by Krivy et al [8], which examines the dependence between the deposition of chlorides and the corrosion layers of two steel bridges; or in the paper written by Cho et al [9], which correlates hydrogen-induced corrosion cracking with maintenance interventions in the wires of cable suspension bridges; or in the paper written by Cabrini et al [10], which evaluates the critical ranges of pH for the initiation of stress corrosion cracking in high-strength steel bars for pre-stressed concrete structures.…”

Hydrogen Embrittlement Susceptibility of R4 and R5 High-Strength Mooring Steels in Cold and Warm Seawater

“…Being the temperature a key factor in electrolytic reactions, the question that arises is whether HE susceptibility of the mooring steels changes from cold to warm seas or not. >690 >17 >50 R3S >490 >770 >15 >50 R4 >580 >860 >12 >50 R4S >700 >960 >12 >50 R5 >760 >1000 >12 >50 R6 >900 >1100 >12 >50 Despite HE is a relevant design factor for high-strength steels and there is plenty of SSRT testing based works in the literature [12][13][14][15][16][17], steel grades and testing conditions show a wide variety (some authors employ straight specimens, others use notched specimens; some works employ hydrogen pre-charging, others study in service re-embrittlement) and none answers the question above concerning the effect of seawater temperature. The work which is presented here is aimed to answer it for high yield strength mooring chain link R4 and R5 steels and R4 mooring accessory steel, under different applied potentials (free corrosion, −850 and −1200 mV), in submerged service in cold (3 • C) and warm (23 • C) seawater.…”

The Structural Evolution of Al86Ni9La5 Glassy Ribbons during Milling at Room and Cryogenic Temperatures

“…In this process, elemental or alloy powders are subjected to highly energetic impact forces, resulting in the formation of new phases. Various kinds of defects and chemical disorder are introduced into crystalline solids during milling [1,2,3]. It was first performed on Fe-based amorphous alloys by Trudeau et al to explore the structural evolution during milling [4].…”