Galvanized Steel Sheets Research Articles

Enhanced predictive corrosion modeling of crevice evolution at e‐coat defects under cyclic climate conditions

AbstractE‐coated galvanized steel sheets are widespread parts of the automotive industry. Hence, the undermining of the organic coating due to defects is a crucial issue. The delamination of an e‐coating is simulated for different cyclic climate conditions using the finite element method to predict the corrosion behavior over several weeks. A semiempirical mixed potential theory model is developed incorporating the time‐of‐wetness, the temperature, and the effect of corrosion products. Furthermore, the spatial orientation of the sheets is considered in the simulation. The trends of experimental delamination widths of corrosion tests are well described by the simulation.

Effect of Surface Abrasive Treatment on the Strength of Galvanised Steel Sheet Adhesive Joints

Effect of Surface Abrasive Treatment on the Strength of Galvanised Steel Sheet Adhesive Joints

Study on Temperature Field of Hot Galvanized Steel Sheet in Cooling Tower

Study on Temperature Field of Hot Galvanized Steel Sheet in Cooling Tower

Influence of classified pore contents on the quasi-static and cyclic strength properties of the welded joint in gas-shielded metal arc welding of galvanized, high-strength steels

High-strength steel sheets are used in the automotive industry to save weight. In particularly, in the chassis area, high-strength steels are constantly replacing the previously used strength classes of 440–590 MPa. In body in white construction, galvanized sheet steel has had long been established use due to its anti-corrosive effect. In chassis production, steel materials are usually processed without galvanizing. In the automotive industry, demand for galvanized steel sheets for chassis production is increasing. Gas-shielded metal arc welding is an established joining process for chassis components. The zinc layer poses difficulties as it evaporates during the welding process and leads to pores in the resulting weld seam. A pore-filled weld seam can reduce the strength of the welded joint. When designing chassis parts, the influence of the pores in the weld seam on the strength properties is an important finding. It has been shown that the resulting pore content of the weld seam can be influenced by the heat input and the welding process used. The following article presents the findings of a low-energy Cold Metal Transfer (CMT) process and a high-energy pulse process on a hot-dip galvanized high-strength steel of strength class 760 MPa in a sheet thickness of 2.5 mm at the lap joint without a gap.

Investigation Techniques of Arson Fire in Low-Temperature Warehouses Using ED-XRF

Investigation techniques for fire prevention in low-temperature warehouses were studied using energy dispersive X-ray fluorescence (ED-XRF). In the first experiment, a sample (galvanized steel sheet plus urethane foam plus sandwich panel) was burned with 500 mL of a flammable liquid (gasoline, thinner, kerosene, and light oil)/ Then, the component change of the sample was measured. In the combustion experiment, there was a difference in the heat of combustion depending on the type of flammable liquid; however, as a result of measuring the component change of the sample with ED-XRF after combustion, the largest component change was measured in the combustion experiment with gasoline. The change was in the order of thinner, kerosene, and diesel. Using ED-XRF, it was possible to distinguish the flammable liquid used in the experiment by measuring the component change of the sample resulting from the difference in the combustion heat of the flammable liquid. A second experiment was conducted under the same conditions as the first experiment, assuming a fire brigade fire suppression condition, and the combustion time of the flammable liquid was limited to 600 s. A combustion characteristic of flammable liquids is that the temperature and heat flux reach the maximum value within 300 s after the start of combustion regardless of the type of liquid. Because the change of composition was confirmed in the order of light oil, it was possible to distinguish the flammable liquid used at the fire site using the ED-XRF measurement result.

A novel corrosion transformation process in aluminum alloy / galvanized steel welded joint

Replacing steel with aluminum alloy is appealing to realize the lightweight of metal structures. Novelis AC 170 PX aluminum alloy and ST06 Z galvanized steel sheets were lap welded by gas tungsten arc welding (GTAW) with ER4047 filler wire and the corrosion behavior of the joint was characterized. The results revealed that the zinc-rich zone had the highest corrosion susceptibility. The difference of localized corrosion between the adjacent area near the rod-shaped and the layered Fe4Al13 phases was explained by galvanic effect. When Zn in the zinc-rich zone was exhausted, the corrosion process of the joint was controlled by the second phases and corrosion products.

REW Application Possibilities for the Production of Combined Metal - Plastic Joints

In this paper, innovative resistance element welding (REW) technology for joining galvanized steel sheets to thermoplastics (PMMA) is introduced. The essence of the innovation is in the use of a special bimetallic joining element consisting of the core made of a Sn60Pb solder, and the sleeve made of a Cu tube. During resistance heating, the solder melts, thus allowing the formation of a metallurgical joint with galvanized steel sheet. Since Sn60Pb solder melting occurs at temperatures (from 183 to 190 °C) be-low the thermal decomposition temperature of most thermoplastics (for PMMA above 300 °C), there is no thermal destruction of the PMMA material around the joint. The mechanical fixation of the thermo-plastic material at the overlap joint is provided by the sleeve made of Cu tube which has a substantially higher strength than a Sn60Pb solder.

Influence of surface treatment on the strength of adhesive joints

The article compared the strength results of single-lap adhesive joints made of galvanized steel sheet. The strength of adhesive joints was determined for two methods of surface treatment - using a degreaser (method B) and with-out a degreaser (method A). The samples were joined using a two-component epoxy adhesive based on Bisphenol A. The strength tests were carried out on a Zwick/Roell Z150 testing machine. The analysis of the surface roughness parameters of the samples for the method A was performed. The highest shear strength value (8.82 MPa) was ob-tained by method B and using P120 abrasive paper. The lowest shear strength value (4.08 MPa) was received using method A and P600 abrasive paper. The maximum values of measured surface roughness parameters were rec-orded for samples prepared with abrasive papers with granulations, respectively: P120, P220 and P180. The low-est values of Ra, Rz and Rt parameters gained using P600 abrasive paper.

Investigation of Microbiological Quality Changes of Roof-Harvested Rainwater Stored in the Tanks

Rainwater has been found to be a valuable source of drinking water in Europe, especially in such crisis situations as those caused by contamination of water uptake into water supply systems, large-scale floods or terrorist attacks (e.g., biological weapons). The microbiological quality of water plays a significant role, which is directly related to the potential health risks associated with harvested rainwater (including rainwater stored in the tanks). Microbial contamination is commonly found in rainwater. However, in the literature, detailed results of qualitative and quantitative microbiological assessments are sparse and remain unexplored. Therefore, the aim of this study was to investigate and analyze changes in the microbiological quality of roof-harvested rainwater stored in the tanks, depending on the collection conditions (type of roof surface), storage duration and season. Authors elucidate that conditions such as storage duration, the season in which rainwater is collected, the roof-like surface types and morphology of the catchment area highly affect rainwater quality. This study showed that rainwater harvested from a galvanized steel sheet roof had the best microbial quality, regarding the lowest number of bacteria, while rainwater from a flat roof covered with epoxy resin was the worst. Further, it was detected that rainwater collected in autumn and spring obtained the best microbiological quality. Moreover, a decrease in the number of bacteria was observed in correlation to storage duration. The water became sanitary safe after six weeks of storage at 12 °C. Its use for purposes requiring drinking water quality before six weeks of storage required disinfection.

OPTIMIZATION OF THE RESISTANCE SPOT WELDING PROCESS OF SECC-AF AND SGCC GALVANIZED STEEL SHEET USING THE TAGUCHI METHOD

This article present the optimization work describes out to joint the dissimilar galvanized steel of SECC-AF (JIS G 3313) and SGCC (JIS G 3302) material. A zinc coating on the surfaces of the galvanized steel sheets will decrease the weldability characteristic of the material. This study used dissimilar galvanised steel sheets to obtain the highest tensile shear strength from the specified resistance spot welding. This research used the Taguchi method with 4-variables and mixed-experimental levels. The mixed-experimental level, namely 2-experimental levels for the first variable and 3-experimental levels for other variables. The highest tensile shear strength was achieved in 5282.13 N. This condition is achieved at a squeezed time of 20 cycles, 27 kA-welding currents, welding time of 0.5 seconds, and holding time of 18 cycles. The S/N ratio analysis has shown the welding current had the most significant effect, followed by welding time, squeeze time, and holding time. The delta values of S/N ratio were 0.79, 0.64, 0.26 and 0.07, respectively. The ANOVA analysis has shown that the P-value of welding current and welding time is 0.006 (0.6%) and 0.015 (1.5%), respectively. This result is expected for optimizing resistance spot welding quality in other materials or significant aspects.

Diffusion Behavior of Al in Zn Coating Layer of Zn-0.2mass%Al Hot-dip Galvanized Steel Sheets with and without Temper Rolling during Aging after Production

Diffusion Behavior of Al in Zn Coating Layer of Zn-0.2mass%Al Hot-dip Galvanized Steel Sheets with and without Temper Rolling during Aging after Production

Metallurgical Analysis as a Useful Method for Fire Investigation: the Case of Galvanized Steel Sheets

In this work, fire simulations were carried out on zinc-coated steel sheets usually employed for the structural parts of furniture, transformer rooms and aeration pipes. The thermal alteration induced by the fire was simulated by heating samples at 13 different temperatures (from 20° C to 1050° C) and for different exposure times (1 h and 6 h) in a laboratory furnace. The metallurgical investigation concerned the surface coloring by photographic analysis, the morphology and chemical composition of the surface oxides by SEM and EDS and the microstructure modifications as a function of the temperature by LOM. The influence of the different parameters was discussed by a statistical approach. The obtained results allowed to associate the temperature to one or more alteration of the steel microstructure and of the color, the morphology and the chemical composition of the surface oxides.

Effect of Cu Addition on the Microstructure and Mechanical Properties of U-MIG Welds on Galvanized Steel Sheets

Effect of Cu Addition on the Microstructure and Mechanical Properties of U-MIG Welds on Galvanized Steel Sheets

Substantial electrode life enhancement in resistance spot welding of galvanised steels through nanolayered multi-layer CrN/(Cr,Al)N coating

ABSTRACT The short electrode life is one of the most important problems associated with resistance spot welding of galvanised steel sheets. In this study, a nanolayered multi-layer CrN/(Cr,Al)N coating was deposited on the tip of the electrode by applying the cathodic arc physical vapour deposition process with the layer thickness of about 30 nm and an overall thickness of 1.1 µm. The electrode life test confirmed that the coating could extend the electrode life up to 125%. The coated electrode showed a significantly lower growth rate (∼0.3 µm per weld), in comparison to the un-coated one (∼1 µm per weld). The degradation of the electrode could be subdivided into two subsequent steps: the degradation of the electrode periphery and the degradation of the electrode tip. The CrN/(Cr,Al)N coating could effectively protect the electrode tip periphery from zinc adhesion and postpone the first stage electrode degradation which delayed the second one.

Multi-Objective Optimization of Process Parameters in Resistance Spot Welding of A36 Mild Steel and Hot Dipped Galvanized Steel Sheets Using Non-dominated Sorting Genetic Algorithm

Multi-Objective Optimization of Process Parameters in Resistance Spot Welding of A36 Mild Steel and Hot Dipped Galvanized Steel Sheets Using Non-dominated Sorting Genetic Algorithm

Experimental Investigations on Capabilities of Resistance Spot Welding and MIG Brazing for Producing Corrugated Beams Using Galvanized Steel Sheets

This paper summarized the research work carried out by a team from Department of Steel Structures and Structural Mechanics, together with Department of Materials Science and Engineering, from University Politehnica Timisoara, which tried to determine the possibility to use welding for obtaining built-up cold-formed steel beams made of corrugated galvanized steel sheets (grade S350GD+Z). There were analyzed two joining processes: MIG brazing and Resistance Spot Welding with the aim to replace the self-drilling screws used until now. The results are very promising and these solutions of joining have beside economic advantages also technical and quality ones.

Experimental Researches on Using Resistance Spot Welding for Built-Up Cold-Formed Beams Made of Corrugated Galvanized Steel Sheets

The paper presents the results of researches carried out by a joint team from Department of Steel Structures and Structural Mechanics, together with Department of Materials Science and Engineering, from University Politehnica Timisoara, focused on the possibility of creating built-up cold-formed steel beams made of corrugated galvanized steel sheets by resistance welding, which will replace the similar beams built by self-drilling screws. Resistance spot welding technologies were developed and tested, together with mechanical testing of the welded joints, which were performed in our laboratories. The results obtained and presented confirm the good quality of the welded joints and, as a result, the good capability of this technology to be used in production, to replace the old type of beams.

Joint Properties of Aluminum Alloy and Galvanized Steel by AC Pulse MIG Braze Welding

In response to global environment and fuel efficiency regulations aiming to reduce CO2 emissions, multi-material structures that use lightweight materials are currently being developed to realize the weight reduction of vehicles in automotive manufacturing. The dissimilar welding of aluminum alloy to steel has great importance, but it is still challenging due to their widely varying thermo-physical properties and the formation of intermetallic compounds. This study aimed to investigate the effect of process parameters on the wettability, mechanical properties, and microstructure in AC Pulse MIG welded joints of AA6061-T6 and galvanized steel sheets. A parametric study on torch aiming position and welding current with EN ratio variation was performed to optimize the process parameters. The result showed that the amount of metal deposition increased with EN ratio. When the EN ratio was higher, the wire feeding speed increased and the heat input process lowered. Moreover, the wetting length increased, ranging from 6.6 to 8.4 mm, and the wetting angle increased from 31.2 to 67.6°, respectively. As a result of the tensile shear test, the maximum tensile shear load of dissimilar welded joints produced at 70 A with a 20% EN ratio was approximately 8.8 kN. From the result of scanning electron microscopy with energy-dispersive spectrometry, FeAl3 IMC was observed at the joint interface, and the IMC layer thickness decreased with EN ratio at 70 A.

PARAMETRIC STUDY OF MULTI-SPOT WELDED LAP SHEAR SPECIMEN FOR TENSILE AND SHEAR STRENGTH

The effect of number of spots, spot spacing, squeezing force, welding current, weld time, overlapping length and sheet thickness on the tensile and shear strength of two similar galvanized steel sheets are investigated through experiments using RSM method and by using software. Similar sheets of galvanized steel sheets are made by resistance spot welding at different processing conditions and these joint populations were tested under lap-shear loading conditions. Specially fabricated fixture is used to load the lap shear specimen in the universal testing machine Regression analysis is done to obtain relationship between shear strength and selected parameters. The experimental results indicate that the failure loads of spot welds in lap-shear specimens increase when number of spot, squeezing force, welding current and sheet thickness increase for the given ranges

Investigation of Thickness Distribution Variation in Deep Drawing of Conical Steel Products

This study investigates the thickness variation behavior of deep drawing conical products under the effect of different forming parameters such as die wall inclination angle, punch velocity, sheet thickness, and sheet metal type. Two types of sheet metal were used, low carbon (AISI 1008) and galvanized steel sheets, of 110 mm diameters circular blanks at 0.9 and 1.2mm thickness formed by tooling set (punch, die, and blank holder). The conical dies inclination angles were at 70ᵒ, 72ᵒ, and 74ᵒ where, the punch velocity was 100, 150, and 200 mm/min. Numerical simulation was conducted using ABAQUS 6.14 where a dynamic explicit solver was used to perform forming of conical products. The results show that maximum thinning occurs at punch nose radius region and maximum thickening in sidewall region and thinning are increased with the increasing of die sidewall angle and sheet thickness. In regard to sheet type, the Lankford coefficients r-value shows a great role in thinning behavior with respect to rolling (r-values direction). The results have shown a good agreement between experimental and numerical work with a maximum discrepancy of 5%.