Improving Thin Strip Profile Using Work Roll Cross and Work Roll Shifting Methods in Cold Strip Rolling

The optimization of rolling parameters in order to achieve better strip shape and to reduce rolling force is a challenge in rolling practice. In this paper, thin strip asymmetrical rolling of aluminum at various speed ratios under lubricated condition has been investigated at various combinations of work rolls cross (WRC) angles and work rolls shifting (WRS) values. The effects of strip width, reduction, and rolling speed on strip shape taking WRC and WRS into consideration are discussed. Results show that strip profile improves significantly when the WRC angle is increased from 0° to 1°, with an associated reduction in rolling force. Increasing WRS value from 0 to 8 mm improves the strip profile as well but not as significantly as when WRC angle is increased. No significant improvement was found in strip shape when the strip width was increased. At higher reduction, the strip shape was improved; a decrease in the rolling force was also observed. A higher speed ratio was found to be effective only at a higher WRC angle. The effect of lubrication on the strip profile was significant. Results indicate that an optimum combination of WRC, WRS, reduction, width, and speed ratio under lubricated conditions can ensure an improved exit strip profile, reduce rolling force, and obtain a better quality strip.

Interaction of Two Water Soluble Heterocyclic Hydrazones on Copper in Nitric Acid: Electrochemical, Surface Morphological, and Quantum Chemical Investigations

Two novel heterocyclic compounds (E)-2-(1-(pyridin-3-yl)ethylidene)hydrazinecarbothioamide (3APTSC) and (E)-3-(1-(2-phenylhydrazono)ethyl)pyridine (3APPH) derived from 1-(pyridin-3-yl)ethanone were synthesized and characterized by various spectroscopic techniques. The corrosion inhibition efficacies of these compounds on copper in 0.1 M HNO3 were screened by electrochemical corrosion monitoring techniques such as potentiodynamic polarization studies and impedance spectroscopy. Investigations clearly established that 3APPH displayed higher corrosion inhibition efficiency on Cu than 3APTSC at all concentrations. The mechanism of inhibition was verified with the help of adsorption isotherms. 3APTSC and 3APPH obeyed Langmuir adsorption isotherm on Cu surface. Thermodynamic parameters such as adsorption equilibrium constant (Kads) and free energy of adsorption (ΔGads) were also evaluated. Potentiodynamic polarization investigations confirmed that the 3APTSC and 3APPH act as mixed type inhibitors. Surface analysis of the metal specimens was performed by scanning electron microscopy. Energy of HOMO and LUMO, their difference, number of electrons transferred, electronegativity, chemical hardness, and so forth were evaluated by quantum chemical studies. Agreeable correlation was observed between the results of quantum chemical calculations and other corrosion monitoring techniques.

An Ecofriendly Initiative for the Corrosion Inhibition of Mild Steel in 1 M HCl Using Tecoma capensis Flower Extract

Corrosion inhibition of mild steel in 1 M HCl in the presence of Tecoma capensis flower extract was carried out by means of mass loss, potentiodynamic polarisation, and electrochemical impedance techniques. The inhibition efficiency varied with concentration of the inhibitor, immersion time, and temperature. The adsorption of the inhibitor on mild steel surface obeys Langmuir’s adsorption isotherm. Thermodynamic parameters reveal that the adsorption process is spontaneous. Electrochemical studies reflect that the inhibitor acts as a mixed-type inhibitor. Surface analytical techniques ascertain the inhibitive nature of the studied inhibitor.

A Novel NDT Method for Coercive Force of Grain-Oriented Electrical Steel Applied in Cigarette Machines

Coercive force of grain-oriented electrical steel applied in cigarette machines is tested by a novel NDT method in which Barkhausen noise was applied. Linear relationship between coercive force and Barkhausen noise of conventional and high-permeability electrical steel was built and the precision of the model was verified. Experimental results show that the coercive force is linearly related to Barkhausen noise. The variation of coercive force with magnetic induction intensity increase was also interpreted in view of magnetic domain changing process, and the correlation formula derivation of MBN and coercive force domain wall was illustrated as well.

Effect of the Strain Kind on the Texture and Microstructure of Low-Alloyed Steel

Crystallographic texture and microstructure of low-alloyed steel after twist extrusion (TE) and subsequent cold rolling along and across the TE axis were studied. The double axial cylindrical texture with axes 110 and 100 parallel to the TE axis and the vortex-like microstructure are formed in the steel during the TE. The subsequent rolling of extruded steel along the TE axis promotes the forming of typical steel rolling texture as well as the microstructure with elongated grains in rolling direction. Typical steel rolling texture as well as the equiaxed microstructure is formed in extruded steel after rolling in the direction transverse to the TE axis. The mechanisms of formation of the texture are discussed.

A Comparative Study of the Inhibitory Effect of Gum Exudates from Khaya senegalensis and Albizia ferruginea on the Corrosion of Mild Steel in Hydrochloric Acid Medium

A comparative study of the inhibitory potentials of gum exudates from Albizia ferruginea (AF) and Khaya senegalensis (KS) on the corrosion of mild steel in HCl medium was investigated using weight loss and gasometric method. The active chemical constituents of the gum were elucidated using GC-MS while FTIR was used to identify the bonds/functional groups in the gums. The two gum exudates were found to be good corrosion inhibitors for mild steel in acidic medium. On comparison, maximum inhibition efficiency was found in Khaya senegalensis with 82.56% inhibition efficiency at 0.5% g/L concentration of the gum. This may be due to the fact that more compounds with heteroatoms were identified in the GCMS spectrum of KS gum compared to the AF gum. The presence of such compounds may have enhanced their adsorption on the metal surface and thereby blocking the surface and protecting the metal from corrosion. The adsorption of the inhibitors was found to be exothermic and spontaneous and fitted the Langmuir adsorption model.

Effect of Alternating Bending on Texture, Structure, and Elastic Properties of Sheets of Magnesium Lithium Alloy

The effect of low-cycle alternating bending at room temperature on the crystallographic texture, metallographic structure, and elastic properties of sheets of MgLi5 (mass) magnesium alloy after warm cross-rolling has been studied. Texture of alloy is differed from the texture of pure magnesium. The initial texture of alloy is characterized by a wide scatter of basal poles in the transverse direction. In the process of alternating bending, the changes in the initial texture and structure (which is represented by equiaxed grains containing twins) lead to regular changes in the anisotropy of elastic properties.

Effects of Moulding Sand Permeability and Pouring Temperatures on Properties of Cast 6061 Aluminium Alloy

Effects of moulding sand permeabilities prepared from the combinations of four proportions of coarse and fine particle size mixtures and pouring temperatures varied from 700, 750, and 800 (±10°C) were studied on the hardness, porosity, strength, and microstructure of cast aluminium pistons used in hydraulic brake master cylinder. Three sand moulds were prepared from each of the 80 : 20, 60 : 40, 40 : 60, and 20 : 80 ratios. The surfaces and microstructures of cast samples were examined using high resolution microscopic camera, metallurgical microscope with digital camera, and scanning electron microscope with EDX facilities. The best of the metallurgical properties were obtained from the combination of 80 : 20 coarse-fine sand ratio and 750 ± 10°C pouring temperature using as MgFeSi inoculant. An 8 : 25 ratio of coarse to fine grained eutectic aluminium alloy was obtained with enhanced metallographic properties. The cast alloy poured at 750 ± 1°C has a large number of fine grain formations assuming broom-resembling structures as shown in the 100 µm size SEM image.

Numerical Investigations on Characteristics of Stresses in U-Shaped Metal Expansion Bellows

Metal expansion bellows are a mechanical device for absorbing energy or displacement in structures. It is widely used to deal with vibrations, thermal expansion, and the angular, radial, and axial displacements of components. The main objective of this paper is to perform numerical analysis to find various characteristics of stresses in U-shaped metal expansion bellows as per the requirement of vendor and ASME standards. In this paper, extensive analytical and numerical study is carried out to calculate the different characteristics of stresses due to internal pressure varying from 1 MPa to 2 MPa in U-shaped bellows. Finite element analysis by using Ansys14 is performed to find the characteristics of U-shaped metal expansion bellows. Finally, the results of analytical analysis and finite element method (FEM) show a very good agreement. The results of this research work could be used as a basis for designing a new type of the metal bellows.

Effect of Electrode Types on the Solidification Cracking Susceptibility of Austenitic Stainless Steel Weld Metal

The effect of electrode types on the solidification cracking susceptibility of austenitic stainless steel weld metal was studied. Manual metal arc welding method was used to produce the joints with the tungsten inert gas welding serving as the control. Metallographic and chemical analyses of the fusion zones of the joints were conducted. Results indicate that weldments produced from E 308-16 (rutile coated), E 308-16(lime-titania coated) electrodes, and TIG welded joints fall within the range of 1.5≤Creq./Nieq.≤1.9 and solidified with a duplex mode and were found to be resistant to solidification cracking. The E 308-16 weld metal had the greatest resistance to solidification cracking. Joints produced from E 310-16 had Creq./Nieq. ratio < 1.5 and solidified with austenite mode. It was found to be susceptible to solidification cracking. E 312-16 produced joints having Creq./Nieq. ratio > 1.9 and solidified with ferrite mode. It had a low resistance to solidification cracking.