“…17 b). These compounds' differing composition and structure makes their properties different as well, including their mechanical properties, as we can see in their toughness (HV) [ 72 , 73 ]. The microfissures included in the solidification often occur in galvanized covering, due to the large difference between the thermal expansion coefficients of the zinc covering and the iron substrate.…”
Section: Resultsmentioning
confidence: 99%
“… Fig. 17 (a) Microstructure of galvanized steel used in the study, showing the phases composing the galvanized layer, magnified 50×, (b) Zone rich in Zn, of the phase diagram in equilibrium Zn-Fe [ 73 ]. …”
“…17 b). These compounds' differing composition and structure makes their properties different as well, including their mechanical properties, as we can see in their toughness (HV) [ 72 , 73 ]. The microfissures included in the solidification often occur in galvanized covering, due to the large difference between the thermal expansion coefficients of the zinc covering and the iron substrate.…”
Section: Resultsmentioning
confidence: 99%
“… Fig. 17 (a) Microstructure of galvanized steel used in the study, showing the phases composing the galvanized layer, magnified 50×, (b) Zone rich in Zn, of the phase diagram in equilibrium Zn-Fe [ 73 ]. …”
“…[2,3] However, the addition of alloying elements to high-strength steel for the improvement of mechanical properties may contradict the coating quality. [4][5][6][7] Especially for highstrength dual-phase (DP) steel, which is the typical automotive steel, limited by the low cooling rate after recrystallization annealing of the hot-dip GI process, it is necessary to increase the alloying element in the steel to obtain a dual-phase structure. [8] Although the frequently-used annealing atmosphere composed of 5 vol% H 2 -N 2 is always reductive to Fe-oxides, the oxidation potential of alloying elements in steel is high enough to facilitate their oxidation, which has an influence on the wettability of steel sheet.…”
The hot‐dip galvanizing behavior of an advanced high‐strength steel DP980 is investigated, focusing on selective oxidation and reactive wetting, as compared with interstitial‐free (IF) steel. The steels are annealed with varying dew points of −50, −25, and 0 °C, and then immersed in a galvannealing bath containing 0.13 wt% dissolved Al. The results show that higher concentrations of Mn and Si elements in DP980 steel result in an increase of nonwettable Mn2SiO4/MnSiO3. The increase in dew point does not promote the internal oxidation of alloying elements in DP980 as in IF steel, and DP980 displays the lowest external oxidation at −50 °C. After galvanizing, Mn and Si oxides are observed above the inhibition layer, which is due to the oxide cracking caused by the mismatch of thermal expansion coefficient between the surface oxides and the steel, and then the oxide flaking and incorporation are caused by the interfacial infiltration through cracks and the formation of intermetallic crystals of Fe–Al and subsequent Fe–Zn. Therefore, IF steel maintains good wetting in the presence of external oxides, while DP980 steel exhibits more external film oxides and poor coating quality at high dew points.
“…After nearly two centuries of use, galvanized steels retain their indispensable role in the automotive, industrial and construction sectors by providing a surface finish that improves service life thanks to barrier and sacrificial protection mechanisms [2,3]. However, although alternatives have been proposed [4][5][6], no universal system has emerged that can replace zinc-coated steels in the mass production of vehicle bodies, due to their combination of corrosion resistance, ductility, and cost-effectiveness.…”
Corrosion processes at cut edges of galvanized steels proceed as highly localized electrochemical reactions between the exposed bulk steel matrix and the protective thin metallic coating of a more electrochemically active material. Scanning microelectrochemical techniques can thus provide the spatially resolved information needed to assess the corrosion initiation and propagation phenomena, yet most methods scan cut edge sections as embedded in insulating resin to achieve a flat surface for scanning purposes. In this work, the galvanized coatings on both sides of the material were concomitantly exposed to simulated acid rain while characterizing the cut edge response using SECM and SVET techniques, thereby maintaining the coupled effects through the exposure of the whole system as rather realistic operation conditions. The cut edges were shown to strongly promote oxygen consumption and subsequent alkalization to pH 10–11 over the iron, while diffusion phenomena eventually yielded the complete depletion of oxygen and pH neutralization of the nearby electrolyte. In addition, the cathodic activation of the exposed iron was intensified with a thinner coating despite the lower presence of sacrificial anode, and preferential sites of the attack in the corners revealed highly localized acidification below pH 4, which sustained hydrogen evolution at spots of the steel-coating interface.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
