In this research, effects of some production parameters such as lead content of the zinc bath, jet wipers distance from sheet surface and galvanizing line speed on corrosion behaviour and structure of hot-dip galvanized coating produced in Mobarakeh Steel Company was investigated. Lead content of the zinc bath was changed in the range of 0.01 to 0.11Wt.% and its effects on the texture and corrosion behaviour and spangle size was studied. Coating texture was determined using X-ray diffraction and Corrosion behaviour of the coating was analyzed employing salt spray and Tafel polarization test. Then, influences of increasing the lead content of the zinc bath, variations of jet wipers distance from the sheet surface and galvanizing line speed on the coating structure were assessed. Results showed that increasing the lead content of the zinc bath, has decreased the relative texture coefficient of basal component and conversely, has increased the relative texture coefficient of high angle pyramids, low angle pyramids and prism plane components. Also, it was discerned that increasing the lead content of the zinc bath would result in the increase of spangle size and number of dull spangles in the surface. After investigation of the effects of increasing the lead content of the zinc bath, increasing the jet wipers distance and decreasing the galvanizing line speed, it was found that gamma layer thickness, the detrimental layer for corrosion resistance and formability, has been increased.

In this study, corrosion resistance of ordinary (non-skin passed) and skin passed hot-dip galvanized steel sheets produced in Mobarakeh steel company was compared with each other. For this reason, lead content of the zinc bath was changed from 0.01 wt.% to 0.11wt.% and the corrosion resistance of the sheets was analyzed. Also, to study the effects of skin pass rolling on the corrosion resistance of the sheets, two skin passed specimens obtained from zinc baths of 0.045 and 0.065 wt.% of lead content were studied. Effect of lead content of the zinc bath and skin pass rolling on (00.2) basal texture component were also investigated. Relative intensity of (00.2) basal texture component was determined using XRD whilst the corrosion behaviour was analyzed employing Tafel polarization test. Results showed that increasing the lead content of the zinc bath would decrease the corrosion resistance and (00.2) basal texture component relative intensity of ordinary coating and conversely, increase the spangle size and darkness of the coating surface. Investigation on the effects of skin pass rolling on the galvanized sheets indicated that in this case, relative intensity of (00.2) basal texture component and spangle size have been decreased and some cracks created in the coating. In addition, it was seen that the corrosion resistance of skin passed specimens, in comparison with ordinary specimens, has been decreased.

In this paper, bare spot defects in hot-dip galvanized sheets were studied in terms of the microstructure and their influence on the corrosion and mechanical properties. Surface characteristics and microstructural features were examined by scanning electron microscopy equipped with energy dispersive spectroscopy microanalysis system. The results showed that the major cause of the bare spots was the lack of wetability of the sheet surface due to contamination, improper heat treatment or chemical composition. Corrosion resistance was evaluated by standard salt spray test. Mechanical properties were examined by tensile testing. The time to red rust was much shorter on the bare spots as compared to other regions, but it appeared that bare spot defects had no significant effect on the mechanical properties of the galvanized steel sheets.

The use of light metals instead of steel in parts of the vehicle body to reduce weight and thus lower fuel consumption has attracted the attention of car manufacturers and researchers. Therefore, this study investigates the dissimilar joining of magnesium and steel sheets by resistance spot welding and the thickness of galvanized steel sheet coating is considered as an effective parameter for the joint strength. The materials used in this work were AZ31B Mg alloy sheet and hot-dip galvanized steel sheet. To investigate the influence of the coating thickness on the joint, two coating thicknesses of 5 and 10 µm were applied to the steel sheet. also to balance the thermal generation on both sides of Mg and Steel sheet, two electrodes with different geometries were used, flat electrode on the steel side and domed electrode on the Magnesium side. Tensile-shear tests were performed on the samples using a tensile testing machine and the microstructure was analyzed using optical and SEM microscopy. The results show a 13% increase in joint strength at a coating thickness of 10 µm. The studies show that increasing the coating thickness from 5µm to 10 µm, reduces the grain size in the nugget  and thus increases the strength.

Galvanizing kettle is one of the main components of hot dip galvanizing process. Welding is the final stage in galvanizing kettle fabrication. In the present research the effect of various welding parameters such as bevel pattern and chemical composition of filler metal on mechanical properties, microstructure and corrosion resistance of welded galvanized steel were investigated. Results showed that symmetry bevel pattern is more effective than the non-symmetry one in developing desired properties in welding zone. Although both patterns developed acceptable mechanical properties in welded coupons. NDT results confirmed that welding zone is free from defects such as porosity, inclusion trapping, lack of penetration and etc. Various tests on the electrode type showed Nilsil electrode is more effective than AMA 1531 and 2000 electrodes in producing sound joints. Corrosion tests showed that silicon is the most detrimental element on corrosion resistance of welded coupons.

In this study the effect of the amount of Nickel in melted Zn and the amount of Si in base metal (steel) and also the duration of immersion time have been studied on three alloyed steels (DIN 1.0012, DIN 1.0037 and DIN 1.0042). Some parameters of coated layers such as total thickness, the thickness of the layers, the uniformity of coated layer, the cohesion of layer and finally the resistance against corrosion has been investigated. For this study optical and scanning electron microscopy which was equipped by EDX system and also salt spray test have been used. By studying several galvanized coatings it is shown that the best uniformity, cohesion and corrosion properties can be achieved by making use of a liquid bath, with 0.1%Ni.