Hot-dip Galvanization Process Research Articles

Achieving energy efficiency and sustainability in galvanization process: A case study on Indian tower manufacturing industry

Abstract There is a significant gap between India’s energy production and its demand. Dependency on energy imports to meet the energy requirement affects the economic growth & overall development. The manufacturing sector consumes a substantial portion of the country’s energy but also holds considerable potential for reducing consumption. This paper presents a case study on an Indian tower manufacturing industry, aiming to achieve energy efficiency and sustainability in the galvanization process through the application of the statistical tool Design of Experiments (DOE). By systematic implementation of 22 factorial model of DOE, the study identified that the excessive zinc coating thickness is the major cause of energy consumption in hot-dip batch galvanization process (HDBGP). It was found that average LPG consumption is minimized at moderate coating thickness. Applying DOE resulted in a 38.67% reduction in LPG consumption when the zinc coating thickness was maintained at a moderate level in HDBGP. DOE provides a systematic mechanism based on experimental data to identify potential causes of problems and offers statistical validation of results. This research focuses on creating an energy-efficient production system and demonstrates the practical application of statistical tools and techniques to achieve sustainable competitive advantages. Highlights Experimental work using the Design of Experiments tool identified excessive zinc coating thickness as the primary cause of high energy consumption in the hot-dip batch galvanization process. Validation of optimized parameters showed that average energy consumption is minimized at moderate coating thickness, resulting in a 38.67% reduction in energy usage. Design of experiments tool provides a systematic mechanism based on experimental data to identify potential causes of problems and offers successful validation of results. Discussion While the significant reduction in LPG consumption enhances energy efficiency and sustainability, excess reduction in coating thickness may compromise the quality and durability of galvanized products, potentially leading to higher long-term costs for maintenance and replacements. Additionally, the focus on statistical tools like DOE alone could divert attention from exploring alternative potential energy-saving technologies and methods that might offer greater benefits. Therefore, it is also essential to consider the broader implications and potential limitations of various approaches in the quest for sustainability and competitive advantage suitable for the existing manufacturing setups. Graphical abstract

Hot-Dip Galvanizing Process and the Influence of Metallic Elements on Composite Coatings

The corrosion of steel materials has become a global issue, causing significant socio-economic losses and safety concerns. Hot-dip galvanizing is currently one of the most widely used steel anti-corrosion processes. With the rapid advancement of science and technology and emerging industries, the performance of pure galvanized products struggles to meet the demands of practical applications in various environments. Consequently, researchers have begun introducing various metals into the zinc solution to form high-performance alloy coatings. This article primarily explains the process flow of hot-dip galvanizing and the impact of metal elements such as Al, Mg, Sn, and Bi on the coating, as well as outlining the major issues currently faced by the hot-dip galvanizing process. The objective is to offer a more comprehensive introduction to those new to the field of hot-dip galvanizing and to provide theoretical insights for addressing production issues.

Enhancement of tribological performance in Li2TiO3/ZrO2 composite coating prepared by industrial hot-dip galvanization process

Hot-dip galvanization is a reliable industrial coating method to tune the surface properties, especially tribology, in an exceptional way. The unique morphological and layered structure of the composite plays a significant role in yielding distinct wear resistance. Lithium titanate (Li2TiO3) has a unique layered structure that can be scientifically used to improve wear resistance in industrial coating systems. In this work, Li2TiO3 has been synthesized using a sol-gel method, and subsequently, a lithium titanate/zirconia (Li2TiO3/ZrO2) composite coating has been prepared by the hot-dip galvanization process. The absence of any other phase in the composite revealed the absence of any possible interaction between the oxides. X-ray Diffraction (XRD), Energy Dispersive Spectroscopy (EDX) and X-ray photoelectron spectroscopy (XPS) confirmed the successful incorporation of the composites in the coating. The surface morphology and the surface roughness of the coatings were studied using Field Emission Scanning Electron Microscopy (FESEM) and Optical Surface Profilometry (OSP). The Li2TiO3/ZrO2 composite coating showed a hardness value as high as 3112 HV, high friction coefficient and 10 times higher wear resistance compared with pure Li2TiO3. This low-cost coating technique and the introduction of Li2TiO3/ZrO2 composite in the hot-dip galvanization process constitute a novel approach to finding a possible material for industrial applications.

Life cycle assessment of zinc and iron recovery from spent pickling acids by membrane-based solvent extraction and electrowinning.

In this paper we conducted a life cycle assessment to evaluate the environmental performance of the valorization of spent pickling acid (SPA) generated in the hot-dip galvanizing (HDG) process. We analyzed the environmental impacts of treating one m3 of SPA, comparing the reference treatment consisting of neutralization, precipitation, stabilization, and landfilling of the metallic sludge (scenario #1), with the innovative LIFE2ACID technology (scenario #2) that produces secondary zinc and iron chloride in solution through non-dispersive solvent extraction (NDSX) and electrowinning (EW). The results showed that the materials credits achieved by the implementation of LIFE2ACID technology turned most of the impact categories evaluated (toxicity, acidification, eutrophication, ozone depletion, etc.) into environmental benefits. Scenario #2 was adapted to achieve either zinc-only recovery (#2.1) or simultaneous iron and zinc recovery (#2.2). The abiotic depletion potential (ADP) of fossil fuels increased slightly from scenario #1 to scenario #2.1 because of the higher energy demand and NaOH consumption of EW, and because only zinc was recovered. However, the valorization of both zinc and iron chloride in scenario #2.2 reduced the ADP-fossil by 27%, compared to the reference treatment. Furthermore, the global warming impact was reduced by 20% and 97% in scenarios #2.1 and #2.2, respectively. With the focus on promoting the circular economy concept, we conclude that the LIFE2ACID technology significantly improves the environmental performance of SPA management. Next steps should consider the life-cycle costs analysis in specific scenarios to find out the trade-off between environmental and economic objectives.

Optimization of Zinc Coating Thickness by Unreplicated Factorial Design of Experiments in Hot-Dip Galvanization Process

Optimization of Zinc Coating Thickness by Unreplicated Factorial Design of Experiments in Hot-Dip Galvanization Process

Enhancement of Tribological Performance in Li2tio3/Zro2 Composite Coating Prepared by Industrial Hot-Dip Galvanization Process

Enhancement of Tribological Performance in Li2tio3/Zro2 Composite Coating Prepared by Industrial Hot-Dip Galvanization Process

The Influence of Hot-Dip Galvanizing on the Mechanical Properties of High-Strength Steels.

Modern high-strength steels achieve their strength exclusively through the manufacturing process, as the chemical composition of these steels is very similar to the composition of standard-quality steels. Typically, hot-dip galvanizing is used to form a protective zinc layer on the steel parts of structures; nonetheless, the material is exposed to high temperatures during the process. With high-strength steels, this can lead to deterioration of the mechanical properties. This study aims to experimentally examine and evaluate the extent of deterioration of the mechanical properties of high-strength-steel members. The effect was studied on specimens made of three different types of steel with the yield strength ranging from 460 to 1250 MPa. For each type of steel, selected mechanical properties—yield strength, tensile strength, and hardness—were determined on specimens with and without hot-dip galvanization, and the obtained results were mutually compared. Our study shows a significant impact of the hot-dip galvanization process on the mechanical properties of some high-strength steels. With the studied types of steel, the yield strength decreased by up to 18%, the tensile strength by up to 13%, and the hardness by up to 55%.

Aluminum coating of twinning-induced plasticity plates via plasma-enhanced magnetron sputtering as a potential industrial technique

Challenges are encountered in the use of the conventional hot-dip galvanization process to deposit a protective layer on the surface of twinning-induced plasticity (TWIP) steel due to the low wettability, which is caused by manganese oxidation on the surface of the steel. In a vacuum environment and after conducting etching on the surface to remove surface oxides, corrosion-resistant aluminum (Al) coatings were prepared on the surface of TWIP steel via the hot-wire plasma-enhanced magnetron sputtering (PEMS) technique under various target and wire discharge currents (Ihot-wires/Itarget). The substrate ion current density at −50 V was as high as 0.88 mA/cm2 under a high hot wire discharge current of 20 A and a low target current of 3 A (20 A/3 A), which was 4 times the ion current under Ihot-wires/Itarget of 5 A/3 A, respectively. According to an analysis of the coatings via pulsed radio frequency glow discharge optical emission spectroscopy, Al, Fe and Mn elements diffused at the interface between the coating and steel substrate. The diffusion layers on both sides of the interface resulted in the Al coating remaining well adhered to the surface of the TWIP steel after Rockwell indentation, scratch testing and Erichsen cupping tests. As the sacrificial and passivated anode, the self-corrosion potential of the dense Al coating increased from −0.770 V of the TWIP steel to −0.471 V, and the corrosion current decreased from 3.91 × 10−4 A/cm2 to 6.14 × 10−5 A/cm2. The dense coating remained undamaged after electrochemical corrosion. Additionally, the structure of the TWIP steel was not affected by the PEMS coating processes.

Genesis and mechanism of microstructural scale deformation and cracking in ZnAlMg coatings

In-depth investigation of the microscale deformation behavior of ZnAlMg coatings is essential to reveal the origin and mechanism of cracking in these coatings. In this work anisotropic microstructural damage and cracking of multiphase Zn1.8Al1.8Mg alloy coatings produced by hot-dip galvanization process on a steel substrate have been studied extensively. Nanoindentation coupled with orientation image microscopy (OIM) is utilized to determine the local micro ductility/strength of the existing phases as well as the orientation dependent micromechanical properties of primary zinc grains. Plastic deformation and damage behavior of the coating are evaluated through in-situ tensile/bending tests, micro-digital image correlation and in-situ OIM analyses. Stress distribution fields and nucleation sites of cracks within the coating microstructure are investigated using extended finite element method. Three quantitative plastic deformation-based criteria are revealed to correlate the coating microstructure to micro-mechanical properties to comprehend the cracking phenomenon. In particular, the binary eutectic is identified as the most detrimental constituent for compatible plastic deformation. Local strain hardening exponent and Schmid factor of primary zinc grains are found to play a significant role in clarifying the cracking behavior. The results of this study are considered as an important step towards designing microstructure controlled ZnAlMg coatings with superior formability.

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.

A holistic framework for assessing hot-dip galvanizing process sustainability

Hot-dip galvanizing is considered one of the most important corrosion protection alternatives for steel; however, its poor environmental performance has been a matter of concern. Even though many researchers have dealt with this topic in the past none of them have jointly dealt with the triple bottom line of sustainable development, and with the random and epistemic uncertainty of its measurement. For that reason, in this work, the sustainability of the hot-dip galvanizing process is investigated integrating: (a) 17 indicators taken from the 4 categories of the GREENSCOPE methodology and one quality performance indicator which is directly related to ISO 1461. (b) The additive utility method for multi-criteria decision-making. (c) The fuzzy analytic hierarchy process used to calculate the relative weights of both indicators and categories by means of a survey. (d) The hierarchical partitioning analysis used for determining the process stages that have a higher impact on sustainability variation, and others useful and suitable statistical tools for data analysis. Furthermore, the proposed framework is tested for a particular hot-dip galvanizing process, considering a random generation of each batch size, steel item characteristics and operating conditions via the kinetic Monte Carlo method. The results show that the stages of pickling and fluxing are critical for the analyzed system and they are not expected to be improved without a significant modification of the process. The proposal outlined in this paper might help designers, process engineers and researchers for a better decision-making process, focusing on the most critical stages while considering the trade-off between the three dimensions of sustainable development.

Investigations of zinc recovery from metallurgical waste

Approximately 7 million tonnes of zinc is annually used for corrosion protection in processes of continuous galvanization and the hot dip processes. Two types of waste are obtained from the process: zinc ash and hard zinc and each of them constitute around 10% of the feed weight. Paper concerns the method of possible separation of metallic zinc from the non-metallic zinc compounds from the zinc ashes – the waste product of hot dip galvanization process. The investigative programme covered the comminution tests of the feed (zinc ash) in selected crushers: jaw crusher, roller crusher and impactor. Results of investigations show that application of individual crushing device results in various breakage of the feed sample. Impact force caused the highest increase in finest particles size fractions of the product, while metallic and non-metallic fractions were comminuted differently. The compression force, in turn, caused the selective comminution, i.e. the breakage of metallic zinc was observed in a higher degree.

Effect of prior electro or electroless Ni plating layer in galvanizing and galvannealing behavior of high strength steel sheet

Galvanization (GI) and galvannealing (GA) of high strength (HS) steel surface is very prone to develop uncoated spots in coating. Sometimes, GA coating may lead to inferior mechanical performance than GI coating as different brittle (Zn-Fe) intermetallic phases are formed in the coating. In this study an innovative prior Ni plating followed by hot dip galvanization and galvannealing process was thought of to obtain good quality of alloy coating. Adherence of molten zinc on the surface of high strength steel sheet improved significantly by prior Ni coating. SEM-EDS and XRD techniques were used for depth analysis of all coatings. The presence of pure zinc phase was confirmed almost entire depth of the coating when GI coating was formed on HS steel substrate without any prior metallic coating whereas the presence of alloy phase was confirmed up to some depth of the coating when GI coating was obtained on HS steel surface with prior Ni coating. The GA coatings with prior Ni plating primarily compose of the desirable Ni5.225Zn41.8 phase. Interdiffusion of Zn and Fe is controlled by Ni layer to get desirable alloy coating. The GI coatings with prior Ni plating layer provides better resistance against chloride attack and GA coating ensured significance improvement in performance than GI coating. The best GA coating was formed on the steel substrate with prior Ni coating by electrodeposition process. This GA coating showed 3–4 times improvement in performance against aggressive chloride attack, lowest powdering and excellent phosphatability with respect to the GA coating on the steel substrate without any prior Ni plating.

Fatigue behaviour of welded structural steel subjected to hot-dip galvanization process

This paper investigates the effect of a galvanizing coating on the fatigue strength of S355 structural steel. While in the literature some results from fatigue tests made on unnotched specimens can be found, very few results are available dealing with notched components and, at the best of authors’ knowledge, no results are available dealing with welded joints. The aim of the present paper is to partially fill this lack of knowledge. A comparison is carried out, between hot dip galvanized fillet welded cruciform joints made by S355 structural steel and not treated welded joints characterized by the same geometry, subjected to a load cycle R=0.34 new experimental data are summarized in the present contribution, in terms of stress range Δσ and averaged stress energy density range ΔW‾ in a control volume of radius R0=0.28mm.

Profilometric Assessment of Surface Condition of Zinc Coatings Formed by the Continuous Galvanizing Method

The paper presents the results of research on surface condition of zinc coatings. Profilometric studies were performed for zinc coatings formed in industrial continuous hot-dip galvanization process and for the same coatings after two years of use. The results include the geometrical shape of 2D and 3D surfaces, distribution of vertices on the surface and roughness and waviness profiles. The parameters Ra, Rz, Sa and Sz were used to define the surface roughness. The study was conducted using FRT Microprof optical profilometer with data acquisition and analysis by MARK III software package.

The Impact of Preheating and Postcooling on Critical-to-Quality Characteristics in Hot-Dip Galvanizing

Hot-dip galvanizing (HDG) is a widely used method for protecting steel against corrosion to ensure structure's life expectancy. The HDG process includes surface preparation, galvanizing, and posttreatment operations where multiple stage parameters are controlled to ensure the optimal utilization of zinc to achieve expected results at minimum cost. In this experimental study, we investigated the influence of preheating temperature and the postcooling methods on critical-to-quality (CTQ) characteristics in HDG at various sample thicknesses. Measured CTQ characteristics included the thickness, hardness, roughness, and microstructure of the coated layers. Obtained results showed that coating thickness decreased as preheating temperature increased and as sample thickness decreased. The selection of the postcooling method impacts largely coating hardness and surface roughness both increased as the thickness of the specimen increased and as the preheating temperature increased. Microstructure analysis of coatings illustrated that there was an increase in the variation of readings as the sample thickness increased and as the preheating temperature decreased. Therefore, HDG parameters must be tuned to account for variations in the thicknesses of galvanized structures to better ensure life expectancy.

Galvanizing and Galvannealing Behavior of CMnSiCr Dual-Phase Steels

Alloying elements, such as Mn, Mo, Si, and Cr, are commonly used to enhance the strength of advanced high-strength steels. Those elements also play an important role in the hot-dip galvanizing (GI) and galvannealing (GA) process. In this study, two kinds of CMnSiCr dual-phase steels were galvanized and galvannealed using a hot-dip simulator to investigate the effect of the alloying elements on the microstructure of the GI and GA coatings. The results showed that the dual-phase steels had good galvanizability because no bare spots were observed and the Fe-Zn phases were readily formed at the interface. However, the alloying reaction during the GA process was significantly hindered. XPS analysis showed that external oxidation occurred under an extremely low dew point [213 K to 203 K (−60 °C to −70 °C)] atmosphere during the annealing prior to hot dipping. However, most of the oxides were reduced during the GI process. After the GI process, the Al was present as solid solutes in the Fe-Zn phase, suggesting that the Fe-Zn phase was formed from the transformation of the Fe-Al inhibition alloy. Meanwhile, the solubility of Si in the ζ phase was extremely low. With continued GA reaction, the ζ phase transformed into the δ phase, which contained approximately 1.0 at.pct Si. The Si also diffused into the Zn layer during the GA reaction. Hence, the ζ phase did not homogeneously nucleate at the steel substrate/Zn coating interface, but was found at the area away from the interface. Therefore, the Fe-Zn phases on the CMnSiCr dual-phase steels were relatively non-uniform compared to those on interstitial-free steel.

CO2 laser welding–brazing characteristics of dissimilar metals AZ31B Mg alloy to Zn coated dual phase steel with Mg based filler

The influence of process variables including heating mode, flux, laser beam offset, and travel speed on the weld bead geometry and joint strength was investigated during laser welding–brazing (LWB) of AZ31B Mg alloy to Zn coated steel. The wettability of molten filler metal on steel surface was studied via a Charge-coupled Device (CCD) camera. The reaction layers along the interface were characterized and the failure mechanism was identified. Dual beam processing was found to preheat the steel substrate and promote the wettability of molten filler metal on the steel surface, thereby improving the corresponding joint strength. Utilizing a flux was found to produce a similar effect on molten filler metal. The optimized range of laser offset was found to be between 0.5 and 1.0mm toward the steel side of the joint. These optimized parameters led to a maximum joint strength of 228N/mm. The joint strength was however found to decrease with increasing travel speed. Cracking was identified with travel speeds greater than 1m/min. Microstructural characterization showed that heterogeneous interfacial reaction layers were produced from the seam head to the seam root of the joint. The reaction layer thickness varied within a certain range when applying different process parameters, suggesting the growth of interfacial layer was not essentially related to the heat input. The primary failure mode of the lap specimens was interfacial fracture. Cracks propagated along the Mg–Zn reaction layer and steel interface. Original Fe–Al phase formed during the hot-dip galvanization process hindered the metallurgical bonding of Mg–Zn reaction layer and steel substrate, which was attributed to interfacial type failure.

Toward Sustainable Progress of Galvanized Steel Sheets

Steel, used in from familiar products such as automobiles and electrical appliances to large structures such as buildings and ships, is inextricable and basic materials of our lives. Steel has made significant progress in both quantity and quality with the development of society. Galvanized steel has evolved most significantly in these 20 or 30 years, being recognized that the steel is the most suitable material for automobiles, with rapid increase in automotive production and emerging demand of anti-corrosion bodies for a background.In this paper, the author firstly would like to describe the development details of galvanized steel, particularly GA (Galvannealed Steel: Hot-dip Zn-Fe alloy steel) achieved through cooperative work among automotive companies, steel companies and paint companies in Japan. At present, galvanized steel became one of the biggest shipping steel products in Japan and in the world as well.If the strong demand for galvanized steel continues in the future like today, it is said that the zinc source will be depleted in 20 years. Aluminum is thought to be the most probable alternative element for zinc, but there are still several problems in its substitution. Eventually, as a tentative measure, only remedy for this matter is to save zinc resources and therefore the development of both hot-dip and electro galvanizing process which makes possible to reduce the zinc usage is required.

Hot-Dip Galvanizing Process Using ZinQuench for Processing Advanced High-Strength Steels

Abstract ZinQuench—Dynamic Galvanizing® (ZQ-DG) is an approach combining coatability improvement and process flexibility to produce advanced high-strength steels (AHSS). During this process, steel strips are gas-jet cooled and quenched from a high tuned temperature into a zinc melt with dynamic flow after annealing. The scientific objective is to develop ZQ-DG to design new AHSS with improved coating quality and mechanical properties simultaneously. The influence and effectiveness of the theoretical considerations are tested experimentally. Process parameters are studied with a laboratory scale hot-dip process simulator. Mechanical characterization of processed multiphase AHSS is carried out through a tensile test and correlated with steel microstructure. Wettability is also evaluated. The actual state of the investigations and results are presented and discussed for the different steels processed. Comparison between laboratory ZQ and conventional hot-dip galvanizing results allows forecasting of the industrial application potential of ZQ-DG to process flexibly new galvanized AHSS with lower alloying element content and resulting in less expensive products with improved mechanical properties.