Galvanized Steel Research Articles

Liquid Metal Embrittlement during Hot Forming of Hot-Dip Galvanized Advanced High-Strength Unalloyed Steels (AHSS)

Abstract Advanced High-Strength Steels (AHSS) are of interest as, owing to their increased strength, they are able to absorb more energy than conventional steels in a car crash. Thus, thinner metal sheets can be used for car design so that vehicle weight and fuel consumption are reduced. The elements Si, Mn, Al, and B are added in order to achieve the desired AHSS alloy properties. Corrosion protection for the automotive sheet metal is mainly ensured by hot-dip galvanizing. The sheets are further processed by hot forming. Hot-dip galvanized steel sheets made of 20MnB8 were examined after high temperature tensile tests. Metallographic examinations were performed on tensile test specimens which were tested at temperatures between 400 and 800 °C and strain rates between 0.05 and 5 s−1. Liquid metal embrittlement was observed at temperatures above 700 °C. Lower strain rates resulted in a smaller degree of liquid metal embrittlement. In order to avoid the occurrence of liquid metal embrittlement during hot forming of galvanized AHSS sheets, the relevant process parameters need to be further optimized.

Simulating the hot dip galvanizing process of high mast illumination poles. Part I: Finite element model development

Hot-dip galvanizing is a protective coating process widely-used to prevent corrosion damage in steel structures. Although the protective coating greatly reduces corrosion rates, there have been many documented cases in which cracks have formed in steel members during the galvanizing process, and the root causes of those cracks remain poorly understood. This paper presents a three-dimensional finite element (FE) model capable of simulating temperature-induced deformations during galvanization of high-mast illumination poles (HMIPs), which can be used to calculate the stress and strain demands at different stages of the galvanizing process. Thermo-mechanical analyses of the FE model were performed using the commercial finite element analysis software Abaqus. A user film-subroutine was developed to simulate the transition of a pole between two different temperature environments throughout four stages of the galvanizing process, dipping, dwelling, extraction, and cooling. Numerical simulation results showed regions of the pole with the highest potential for crack initiation at critical stages of the galvanizing process. Mechanical response variables of the simulations were highest at the bends of multi-sided poles, at the welded connection between the base plate and the pole. Inspection reports show that many cracks have been detected at this location, which corroborates the validity of the FE model.

Enhancing the Aesthetics and Transportability of Container-Kiosk in Ghana

Over the years, container-kiosk have been used in Ghana as point of sale joints where various services are carried out. Although the initial intent of these temporary structures are purposely for sales, there has been a pressing need for owners of such structures to use them for both business and as an abode. This is as a result of the high cost of accommodation in our cities and over-crowding in these cities due to rural-urban migration. Aside defeating the primary use of these structures, they have not been designed and fabricated for easy transportability. These temporary structures both deface the environmental aesthetics of our cities and incur high financial burden on owners and the state when being transported or relocated. The objective of this research was to redesign container-kiosk with much emphasis on their beauty and demountability for easy transportability. The research employed the descriptive and studio based research design and used observation and interview to soliciting information from a sample size of 186, drawn from an accessible population size of 372. Explorations were made into the nature of materials used for fabricating these container-kiosks. It was found that mild steel rust faster than galvanize steel and also majority of these container-kiosk owe their rust to the concrete pedestal upon which they are mounted as well as unfavourable atmospheric conditions. Is was again found that much effort had not been made to improve the Aesthetics as well as the ease with which these temporary structure can be demounted, rather artisans copied the form in which ISO shipping containers have been formed. It is therefore recommended that design concepts and findings of this research be considered when constructing Demountable containers.

Effect of nano coating materials on reduction of soil adhesion and external friction

Increasing energy consumption in agriculture due to the development of mechanization, necessitates optimization of the devices used in this sector. In this research, the effect of five materials of St37 steel (SST37) plate, galvanized steel (GAS), fiberglass(Glass Fiber Reinforced Polymer) (GRP), and two nano-coated plates of titanium nitride and tantalum carbide (TiN-TaC) produced in a plasma environment with by sputtering technique in a thickness of about 100 nm. The friction and adhesion coefficient of three types of sandy loam soil, loam, and clay loam soil were investigated at four moisture contents of 10, 20, 30 and 40% (d.b) and four sliding speeds of 0.1, 0.2, 0.3, and 0.4 m/s. A precise measuring system was developed to measure the adhesion and friction coefficient of soil and metal. The adhesion and external friction angle increased with increasing moisture content in all three soil textures. Also, with increasing the sliding speed, the coefficients of friction and adhesion increased. It was found that the coefficient of friction and adhesion were significantly affected by the tool material type. Nano-coated plates exhibited a much lower friction angle and less adhesion than steel due to hydrophobic surfaces and roughness in the nanoscale. The adhesion in the steel blade was 9 times of nano-coated plates and the friction angle was 2.5 times of these plates, which can be very important in the design of tillage implements. Also, fiberglass and galvanized steel showed adhesion and friction lower than those of SST37.

Study on corrosion behavior of storage tanks filled with biodiesel and the blends

Corrosion is one of rising problem in the use of biodiesel. Improper storage of biodiesel may cause corrosion to occur faster and give a worse damage effect. Biodiesel is commonly stored longer in B100 (neat biodiesel). In this work, the corrosion characteristics of three different material of tanks for B100 and the blends (B20) are examined. Those metallic materials used are Stainless Steel 304 (SS), Carbon Steel (CS), and Galvanic Steel (GS). The fuel has been monitored every 45 days in 135 days. The corrosion occurrence related to some changes in the physical properties of the fuel stored. It is also identified through the change in tanks’ thickness, weight, and the morphology of metal tank surfaces. The result shows a great change in biodiesel physical properties occurred in GS tank, where the BXX acid value increased by 25.39% and the water content changed to 43.18%. While, biodiesel which stored in SS tank performed best with minor change in base and wall thickness with the change of under 1% and the weight change was only 0.02%. In a certain of time, the morphological examination shows CS as the recommended material for biodiesel storage due to uniform corrosion performance.

The Effect of Hot Dip Galvanizing Temperature to Corrosion Rate of Steel as the Material for Chopper Machine

This study aims to find material steel for animal feed chopper machine which is not easily corroded with method of hot dip galvanizing (HDG). Steel as machinery components or construction often gets broken before the predicted time because of corrosion. The HDG method was begun by pre-treatment process which were polishing, degreasing, rinsing I, pickling, rinsing II, fluxing, and drying. The main process of galvanizing was done by dipping in 98% of zinc solution with temperature variation of 430, 450, 470, and 490°C. The coating thickness measurement was run with Coating thickness NOVOTEST TP-1M. The corrosion was tested with electrochemical method of potentiodynamic polarization with AUTOLAB PGSTAT 128. The highest value of coating thickness was at galvanized temperature of 490°C which was 88.9 ± 3.24%. The value of standard deviation was indicated by how much the coating homogeneity formed. This was in line with the amount of corrosion rate at galvanized temperature of 490°C. The highest corrosion rate values in H2SO4 and NaCl environment were 1.18 and 0.21 mm/year. The highest hardness value of Zn layer is galvanizing temperature of 490°C which rises 41.71% of the base metal. The coating thickness, corrosion and surface hardness test have thee good agreement.

Study of metal electrodeposition by means of simulated and experimental polarization curves: Zinc deposition on steel electrodes

Zinc is one of the most used metal for galvanic coating, being applied on steel by hot dip galvanizing, electroplating or thermal spraying. The study of zinc electrodeposition is usually performed by interpreting polarization curves. Despite the efforts in investigating polarization curves, a number of gaps remain unfilled. This work performed a study on polarization curves for zinc deposition on steel. The experimental curves were obtained in an electrochemical cell following well-established procedures. The theoretical curves were modeled considering individual Butler-Volmer equations for each reaction. As results, qualitative and quantitative approaches of zinc deposition on zinc and on steel were established and a mechanism for interpreting the obtained polarization curves was proposed. A thermodynamic description for the occurrence of underpotential deposition was also presented.

Effects of Nitrided and Chrome Plated Die Surface Roughness on Friction in Bending Under Tension

<div class="section abstract"><div class="htmlview paragraph">Different die surface polish conditions result in a noticeable effect on material flow in stamping, which can lead to splitting, wrinkling, or other surface stretching issues associated with different friction conditions. These occurrences are not only limited to the non-coated dies, but also nitrided and chrome plated dies. To ensure quality control of the stamped parts, the die conditions corresponding to different polishing procedures need to be developed based on measurable parameters such as surface roughness (Ra). The intent of this study is to investigate the effects of nitrided and chrome plated die surface roughness on friction. The Bending-Under-Tension (BUT) test was conducted to simulate the stamping process due to the test’s versatility and flexibility in changing test parameters. The test involves moving sheet metal across a 3/8-inch diameter pin, which substitutes for a die surface. The pin can be modified by material, heat treatment, coating, and surface roughness. Pins were made of D6510 steel and heat treated to 54-58 HRC. Two different die polishing procedures were developed. The first is the progressive polishing procedure, which is applied to the pins after heat treatment but before coating. The second polishing procedure added a second stage single polishing procedure after final die surface treatments were completed. Half of the pins were nitrided and the other half were chrome plated. The BUT test used hot-dipped galvanized (HDGI) bake-hardenable 210 MPa tensile strength steel (BH210). Results indicate the 600 grit# polish condition generates the lowest average friction coefficient among all polish conditions regardless of the die surface treatments. Additionally, 3.4 μin and 5 μin is the optimal die surface roughness (Ra) for the chrome plated dies and nitrided dies, respectively, in forming HDGI BH210 steel.</div></div>

Intermetallic phase kinetic formation and thermal crack development in galvanized DCI

A new class of material characterized by mechanical properties close to the traditional low and medium carbon steel is the Ductile Cast Irons (DCIs). High castability and low production costs allow them to be used in many fields, ranging from automotive to piping. In this class of iron-based alloy the content of carbon is mainly localized in the graphite nodules, which are dispersed in a metallic matrix characterized by different phases: ferrite, austenite, pearlite, martensite or their mix, depending on the chemical composition and the heat treatment. Metallic matrix is subjected to the corrosion phenomenon, and, for this reason, the study and the development of traditional and innovative protection techniques are important, mainly in critical applications. Hot dip galvanizing is one of the investigated protections because the zinc is able to protect the iron-based alloys thanks to the reduction potential that is lower than the iron one. In this work, a ferritic-pearlitic DCI (GS500) is galvanized by using a pure Zn bath at 440°C in order to generate a zinc coating at different dipping time. The presence of thermal cracks is observed by means of a Scanning Electron Microscope (SEM).

Enhancement of physico-chemical and anti-corrosive properties of tung oil based polyurethane coating via modification using anhydrides and inorganic acid

Tung oil (TO) based polyol was synthesized through hydroxylation and alcoholysis. Modification of synthesized polyol (purified alcoholysed hydroxylated tung oil (PAHTO)) was carried out using the definite proportion of phthalic anhydride (PA), maleic anhydride (MA) and boric acid (BA) acting as modifiers as well as cross-linkers. Modified polyurethane (PU) was prepared by reacting the modified polyol with toluene diisocyanate (TDI) in NCO/OH = 0.7 ratio. Spectroscopic studies of modified PU confirmed the modification process. Anti-corrosive properties of the modified PU on galvanized steel (GS) was found better than mild steel (MS) in aqueous (3.5 wt%) NaCl solution environment. The resultant surface hydrophobicity and roughness characterization along with its morphology were analyzed using the atomic force microscopy (AFM) and contact angle (CA). Chemical resistance properties, as well as the physical properties such as gloss, scratch hardness, adhesion and impact resistance, were evaluated using standard methods. It was observed that the cross-linking moiety in the backbone of the PU chain exhibits better physico-chemical properties compared to the unmodified PU. The thermal stability of modified PU coating was examined by differential scanning calorimetry (DSC) and thermal gravimetric analysis (TGA) which showed that thermal properties like decomposition and glass transition of the materials increase with PA and BA molar ratio. The potentiodynamic and electrochemical impedance spectroscopy (EIS) study inferred better corrosion resistance property of PU with the incorporation of PA and BA which prepare itself for several industrial and commercial applications.

Sebacic acid as corrosion inhibitor for hot‐dip galvanized (HDG) steel in 0.1 M NaCl

The potential of sebacic acid as a corrosion inhibitor for hot‐dip galvanized steel in 0.1 M NaCl solution has been investigated. Different concentrations of the organic acid have been tested in order to understand the inhibition mechanism of the compound. The electrochemical test revealed a competitive mechanism between the dissolution of the metal in the acidified solution and the inhibition provided by the dicarboxylic species. The formation of a whitish layer consisting of zinc carboxylates and corrosion products was proved by means of scanning electron microscopy (SEM) investigation combined with Fourier transform infrared (FT‐IR) analysis. A bidentate bridging coordination between the Zn(II) and the carboxylic species is suggested.

One-step fabrication of bionic superhydrophobic coating on galvanised steel with excellent corrosion resistance

Bionic super-hydrophobic coating with excellent corrosion resistance was fabricated on galvanised steel (GS) via a one-step spontaneous deposition process at room temperature. Results showed that the superhydrophobic surface was covered with hierarchical petal-like and coral-like micro/nano structures along with low surface energy functional groups. The super-hydrophobic coating, with a static water contact angle as high as 165 ± 2.3°, exhibits excellent water-repellent and rolling-off property. Potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) results demonstrated that the superhydrophobic coating significantly improve the corrosion resistance of GS sheet in 3.5% NaCl aqueous solution. The salt spray exposure result also showed highly productive effect against the penetration of chloride ions. The super-hydrophobic coating on GS sheet served as an effective corrosion barrier, inhibiting the electrons and ions transfer between substrate and electrolyte.

Surface modification of carbon steel by ZnO-graphene nano-hybrid thin film

Application of corrosion resistant coatings is one of the most widely used means of protecting steel. Zinc coated (galvanize) steel, is well known for galvanic protection of steel substrates and nowadays, particular attention has been paid to the coupling of graphene oxide (GO) with metallic materials, in order to lessen corrosion rate. In this research, an isopropanol supercritical reducing environment prepared to make zinc ions bond directly with graphene oxides, to form a button shape hybrids of ZnO-Graphene (ZnOG). The hybridized bonding between zinc and graphene oxide is confirmed by Fourier Transform Infra-Red analysis. And the morphology revealed, using a Field Emission Scanning Electron Microscope. ZnOG dip-coated thin film on a carbon steel St.32 substrate, was further analyzed by X-ray diffraction study and Energy Dispersive Spectroscopy (EDS) on the micrographs to verify the presence of ZnOG buttons on the surface. Polarization plots show that ZnOG has lowest corrosion rate in both 3.5 wt% NaCl and wet H2S electrolytes, with respect to conventional or GO composited galvanize steel. In fact non-hybridized GO in galvanize coating, increases corrosion rate in wet H2S by 14 times. This is further verified by Warburg formation of Nyquest impedance plots, that GO flakes make a path for corrosive ion diffusion across the coating. But hybridizing GO into the coating, provides a robust barrier against corrosion. In conclusion, Mott-Schottky analysis revealed ZnO semiconductor properties, even for conventional hot dip galvanize steel.

Effect of Sodium Silicate Sealing on Corrosion Resistance of TiO2Conversion Film on Hot-dip Galvanized

Effect of Sodium Silicate Sealing on Corrosion Resistance of TiO2Conversion Film on Hot-dip Galvanized

Thermo-chemical Fluid Flow Simulation in Hot-Dip Galvanizing: The Evaluation of Dross Build-Up Formation

This paper presents a new computational framework to investigate the driving force for the formation of intermetallic dross particles in the zinc bath and dross build-up on the bath hardware. This is a major problem in continuous hot-dip galvanizing lines. The Computational Fluid Dynamics (CFD) model calculates the turbulent thermo-chemical flow conditions within the liquid melt. A detailed modeling of the steel strip–liquid interface enhances this approach, by means of a conjugated heat transfer calculation and a spatially resolved, temperature- and concentration-dependent iron dissolution and aluminum uptake. The heart of the computational framework is a thermodynamic model, which assesses the driving force for the formation or dissolution of dross particles in the bath and dross build-up on stationary and rotating equipment. The simulation results are validated with temperature and species depth profile measurements. The applicability of the CFD model is shown by investigating the locally resolved aluminum uptake and iron dissolution at the steel-strip surface, and the multi-physics conditions in the region near the roll. The novel approach of evaluating the thermodynamic driving force enables the assessment of the formation of dross build-up at the roll surface.

Predicting the durability of zinc coatings based on laboratory and field tests

Galvanizing is one of the most common methods of corrosion protection. For the deposition of zinc coatings used such methods as gas-thermal deposition, thermal diffusion saturation in powder, hot-dip galvanizing, cladding, and galvanic precipitating during electrolysis. The hot-dip galvanizing is the most common method, which is used in construction, automotive and other industries. Paper presents the results of research of zinc coatings used in sea conditions. The aim of the work was to determine an acceleration factor by comparing the corrosion rate in laboratory conditions with the data from field tests. Laboratory studies were carried out in a salt fog chamber. Samples were periodically removed from chamber to build the dependence of the corrosion rate on the exposure time. Field tests were carried out at the exploitation area. Result of the work is a guide that allows to predict the corrosion rates of zinc coatings using laboratory tests. The advantage of this test method is shorter time of exposure in comparison with field test.

Analysis of the Al and Ti additions influences on phases generation and damage in a hot dip galvanizing process

Cheap iron-based alloys, such as Ductile Cast Irons (DCIs) and low carbon steels, are more and more used in the mechanical field because they are characterized by good strength and good workability. However, the low value of electrochemical potential of low carbon steel leads to quick environmental corrosion that can compromise the operative life of mechanical components. Therefore, it is important to protect them against corrosion even for safety and reliability reasons. The use of a traditional protection technique, like Hot Dip Galvanizing (HDG), allows low costs too. In this work, the phase formation during HDG process is presented and discussed. In particular, the influence of Al and Ti additions on the pure Zn bath is shown in the metallographic analysis, presenting also the results of pure Zn bath.

Quality analysis of galvanized pipes applied to natural gas installations in civil construction

Some natural gas distributors for residential and commercial buildings in Brazil use galvanized steel tubes and fittings manufactured by the hot-dip zinc process that are supported by the specifications contained in the Brazilian Standards. Zinc coating is one of the most widely used methods to provide protection against corrosion. It is therefore essential that national and international tube manufacturers and installation and maintenance companies in civil construction also meet the defined national and international standards, especially when the tubes and fittings are used for natural gas in residential buildings. This two-way communication could eliminate most issues that delay or prevent superior galvanizing quality. Low standards lead to the deterioration of the zinc coating and the metal base of the pipes, which may lead to leaks, such as fluids, flammable gases, and other toxic products, and potentially jeopardise residential and commercial buildings. Here the importance of ensuring the quality of zinc-coated pipes is demonstrated through a series of analyses on natural gas pipe corrosion used in civil construction in Brazil. Based on Brazilian standards, the zinc mass determination per square meter, uniformity tests (Preece test) and metallographic evaluation of the deposited zinc layer were carried out on samples of galvanized tubes for natural gas. An experiment was also developed to reproduce the same conditions of subfloors (mortar beds) where there is penetration of water and humidity reaching the galvanized pipes. Metallographic analysis showed that samples of galvanized tubes by the hot-dip zinc galvanizing can have discontinuities and defects in zinc layer. Such defects associated with penetration and/or permeation of the water and humidity in the subfloor favor the corrosive process and consequently can cause gas leaks and probable accidents in residential buildings. Keywords: Corrosion, galvanized steel, zinc coating, quality, natural gas pipes, civil construction.

Preface to the Special Issue “Fundamentals and Application Technologies for High-performance Hot-dip Galvanized Coatings”

Preface to the Special Issue “Fundamentals and Application Technologies for High-performance Hot-dip Galvanized Coatings”

热镀锌产业无铬钝化的研究进展

热镀锌产业无铬钝化的研究进展