• Corrosion Science and Technology
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• 제4권1호
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• pp.8-14
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• 2005

The corrosion behaviour of mild steel in phosphoric acid solution in the presence and absence of pollutants viz. Chloride, Fluoride and Sulfate ions at 302K-333K was studied using mass loss and potentiostatic polarization methods. The addition of chloride and sulfate ions inhibits the mild steel corrosion in phosphoric acid while fluoride ions stimulate it. The effect of temperature on the corrosion behaviour of mild steel indicated that inhibition of chloride and sulfate ions decreased with increasing temperature. The adsorption of these ions (Chloride and sulfate) on the mild steel surface in acid has been found to obey Langmuir adsorption isotherm. The values of activation energy (Ea) and free energy of adsorption ($\Delta$) indicated physical adsorption of these ions (chloride and sulfate) on the mild steel surface. The plot of $logW_{f}$ against time (days) at 302K gives a straight line, which suggested that it obeys first order kinetics and also calculate the rate constant k and half-life time $t_{1/2}$.

• 대한조선학회지
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• 제8권2호
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• pp.13-24
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• 1971

When friction welded material is actually used for parts of a machine, its fatigue strength is an important problem. Especially, there is no report which deals with mechanical properties of friction welded mild steel(S20C) and stainless steel(SUS27B). In this study are compared the compared the characteristics of such specimens as mild steel, stainless steel and welded material in the S-N diagram. And metallurgical consideration is directed to HAZ. The obtained results in these studies are summarized as follows; 1) The fatigue strength of welded material is slightly less than those of mild steel and stainless steel. 2) In the S-N diagram the knuckle point of welded material has larger number of cycle than that of stainless steel. 3) The fatigue notch factor of welded material is between those of mild steel and stainless steel. 4) mHv is the largest on the weld interface. It is larger before than after fatigue test on the stainless steel side. On the mild steel side it is the way around.

• Journal of Welding and Joining
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• 제14권1호
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• pp.68-74
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• 1996

The microstructure of HAZ and the mechanical properties in weldments such as hardness and toughness were studied for mild steel and AH36 grade TMCP steel, as increasing heat input with electrogas welding process. The results of this study can be summarized as follow: 1) In the HAZ of mild steel, the width of coarse grained zone was larger than that of the nomalized zone, however in the case of TMCP steel, the nomalized zone was wider than the coarse grained zone. 2) The grain size of HAZ become coarse with increasing heat input. And at the same heat input, the grain size of TMCP steel was more coarser than that of mild steel. 3) According to the change of heat input, the deviation of hardness values was not significant, and the maximum values of hardness was not in HAZ but in the weld metal. And the hardness values in root part was higher than in face part. 4) Even though the HAZ grain size of mild steel was larger than that of TMCP steel, the impact values for mild steel was higher than those for TMCP steel, and the impact values in face part was higher than those in root part.

• Journal of Electrochemical Science and Technology
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• 제4권2호
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• pp.81-87
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• 2013

Inhibition of corrosion of mild steel in sulphuric acid by acidic extract of Jatropha Curcas leaves has been studied using weight loss and thermometric measurements. It was found that the leaves extract act as a good corrosion inhibitor for mild steel in all concentrations of the extract. The inhibition action depends on the concentration of the Jatropha Curcas leaves extract in the acid solution. Results for weight loss and thermometric measurements indicate that inhibition efficiency increase with increasing inhibitor concentration. The adsorption of Jatropha curcas leaves extract on the surface of the mild steel specimens obeys Langmuir adsorption isotherm. Based on the results, Jatropha curcas leaves extract is recommended for use in industries as a replacement for toxic chemical inhibitors.

• 대한화학회지
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• 제58권1호
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• pp.85-91
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• 2014

The corrosion behavior of aluminum and mild steel in hydrochloric acid medium was studied using a nicotinic acid hydrazide as inhibitor by potentiodynamic polarization, electrochemical impedance spectroscopy technique and gravimetric methods. The effects of inhibitor concentration and temperature were investigated. The experimental results suggested, nicotinic acid hydrazide is a good corrosion inhibitor for both aluminum and mild steel in hydrochloric acid medium and the inhibition efficiency increased with increase in the inhibitor concentration. The polarization studies revealed that nicotinic acid hydrazide exhibits mixed type of inhibition. The inhibition was assumed to occur via adsorption of the inhibitor molecules on the aluminum and mild steel surface and inhibits corrosion by blocking the reaction sites on the surface of aluminum.

• Corrosion Science and Technology
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• 제22권1호
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• pp.10-20
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• 2023

Because of its inexpensive cost, mild steel is frequently employed as a construction material in different industries. Unfortunately, because of its limited resistance to corrosion, a protective layer must be applied to keep it from decaying in acidic or basic environments. The presence of heteroatoms, such as nitrogen, oxygen, and pi-electrons in the Schiff base could cause effective adsorption on the mild steel surface, preventing corrosion. The weight loss method and scanning electron microscopy (SEM) were used to investigate the inhibitory effects of APIDO on mild steel in a 1 M hydrochloric acid environment. The efficiency of inhibition increased as the inhibitor concentration increased and decreased as the temperature increased. The SEM analysis confirmed that the corrosion inhibition of APIDO proceeded by the formation of an organic protective layer over the mild steel surface by the adsorption process. Simulations based on the density functional theory are used to associate inhibitory efficacy with basic molecular characteristics. The findings acquired were compatible with the experimental information provided in the research.

• Journal of Welding and Joining
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• 제15권5호
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• pp.104-114
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• 1997

The microstructure and bond strength were investigated on the SiC/SiC and SiC/mild steel joints brazed by Ag-5at%Ti alloy. Ag-5at%Ti-2at%Fe and -5at%Fe brazing alloys were also used to see the effects of Fe addition on the bond strength of SiC/SiC brazed joints. Brazing temperature and brazing gap were selected and examined as brazing variables. The microstructure of SiC/SiC brazed joints was affected by Fe addition to the Ag-5at%Ti alloy, but the bond strength was not. Increasing brazing temperature also changed the microstructure of $Ti_5Si_3$ reaction layer and brazing alloy matrix of the SiC/SiC and SiC/mild steel joints, but not the bond strength. Brazing gap had a great effects on the bond strength. Decreasing brazing gap from 0.2 mm to 0.1 mm in SiC/SiC brazing increased the bond strength from 187 MPa to 263 MPa and, in SiC/mild steel brazing, from 189 MPa to 212 MPa. It was concluded that the most important parameter on the bond strength in SiC/SiC and SiC/mild steel brazing was the relative ratio between brazing gap and specimen size.

• Corrosion Science and Technology
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• 제23권1호
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• pp.20-32
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• 2024

Metal corrosion in acidic environments is a major issue in various industrial applications. This study evaluates the 4-piperonylideneaminoantipyrine (PPDAA) corrosion inhibition efficiency for mild steel in a hydrochloric acid (HCl) solution. The weight loss method was used to determine the corrosion inhibition efficiency at different concentrations and immersion time periods. Results revealed that the highest inhibition efficiency (94.3%) was achieved at 5 mM concentration after 5 hours of immersion time. To inspect the surface morphology of the inhibitor film on the mild steel surface, scanning electron microscopy (SEM) was used before and after immersion in 1.0 M HCl. Density functional theory (DFT) calculations were performed to investigate the molecular structure and electronic properties of the inhibitor molecule to understand the corrosion inhibition mechanism. Theoretical results showed that the inhibitor molecule can adsorb onto the mild steel surface through its nitrogen and oxygen atoms, forming a protective layer that prevents HCl corrosive attack. These findings highlight the potential of PPDAA as an effective corrosion inhibitor for mild steel in HCl solution. Moreover, combining experimental and theoretical approaches provides insights into the mechanism of corrosion inhibition, which is essential for developing effective strategies to prevent metal corrosion in acidic environments.

• 한국산업보건학회지
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• 제8권2호
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• pp.209-223
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• 1998

The aim of this study was to evaluate welders' exposure to hexavalent chromium (Cr(VI)) and nickel (Ni) during welding operations in a Korean shipyard. The airborne Cr(VI) and Ni concentrations were measured during metal inert gas (MIG) welding on mild and stainless steel, and manual metal arc (MMA) welding on mild steel. The geometric mean (GM) of Cr(VI) concentrations inside the welding helmet during MIG welding on mild steel were $0.0018mg/m^3$ inside a ship section, and $0.0015-0.0026mg/m^3$ at the welding shops. All of the personal breathing zone air samples were below the American Conference of Governmental Industrial Hygienists (ACGIH) Threshold Limit Value ($TLV^{(R)}$) of $0.01mg/m^3$. Conversely, eighty-eight percent(21 of 24) of the personal breathing zone air samples exceeded the National Institute for Occupational Safety and Health (NIOSH) recommended exposure limit of $0.001mg/m^3$. Ni was not detected on 20 of 23 air samples collected during MIG welding on mild steel. The three Ni samples above the limit of detection ranged from 0.015 to $0.044mg/m^3$. The GM of Cr(VI) concentrations during MMA welding on mild steel were $0.0013mg/m^3$, but Ni was not detected in the air samples during this operation. It is assumed that the airborne Cr(VI) and Ni during mild steel welding were derived from the base metals which contained about 0.03% Cr and 0.03% Ni. The GM of airborne total Cr, Cr(VI) and Ni concentrations during MIG welding on stainless steel were 4.02, 0.13 and $0.86mg/m^3$, respectively, and the levels of Cr(VI) and Ni were above the ACGIH-$TLV^{(R)}$. Cr(VI) comprised about 35.5% of the total chromium(Cr) from MIG welding on mild steel, and about 8.4% of total Cr from MIG welding on stainless steel. The ratios of Cr(VI) to total Cr were significantly different among welding shops. It was concluded that welders were exposed to high levels of Cr(VI) and Ni during welding on stainless steel, and were exposed to low levels of Cr(VI) even during welding on mild steel.

• 한국재료학회지
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• 제22권11호
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• pp.591-597
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• 2012

For heat exchanger applications, 2-ply clad materials were fabricated by rolling of aluminum (Al) and mild steel sheets. Effects of annealing temperature on interface properties, especially on inter-layer formation and softening of strain hardened mild-steel, for Al/mild steel clad materials, were investigated. To obtain optimum annealing conditions for the Al/mild steel clad materials, annealing temperature was varied from room temperature to $600^{\circ}C$. At the annealing temperature about $450^{\circ}C$, an inter-layer was formed in an island-shape at the interface of the Al/mild steel clad materials; this island expanded along the interface at higher temperature. By analyzing the X-ray diffraction (XRD) peaks and the energy dispersive X-ray spectroscopy (EDX) results, it was determined that the exact chemical stoichiometry for the inter-layer was that of $Fe_2Al_5$. In some samples, an X-layer was formed between the Al and the inter-layer of $Fe_2Al_5$ at high annealing temperature of around $550^{\circ}C$. The existence of an X-layer enhanced the growth of the inter-layer, which resulted in the delamination of the Al/mild-steel clad materials. Hardness tests were also performed to examine the influence of the annealing temperature on the cold deformability, which is a very important property for the deep drawing process of clad materials. The hardness value of mild steel gradually decreased with increasing annealing temperature. Especially, the value of hardness sharply decreased in the temperature range between $525^{\circ}C$ and $550^{\circ}C$. From these results, we can conclude that the optimum annealing temperature is around $550^{\circ}C$ under condition of there being no X-layer creation.