Analysis of the inhibiting action of pectin on corrosion of AISI1040 dual-phase steel with ferrite–martensite and ferrite–bainite structure: a comparison in 0.5 M sulphuric acid

The adsorption of pectin and corrosion inhibition of dual-phase AISI1040 steel with ferrite–martensite and ferrite–bainite structure in 0.5 M sulphuric acid (H2SO4) solution have been investigated using the weightloss method. This work investigates the adsorption mechanism and quantum chemical calculations of pectin. For a specific set of parameters such as immersion time and concentration of inhibitor, the maximum inhibition efficiency of 83.36% is observed. The inhibition efficiency increased with pectin concentration and decreased with immersion time at 30 ℃. The results from the statistical analysis show that the concentration of inhibitor is having the highest influence with a 43.87% contribution on the inhibition efficiency. The adsorption study revealed that the Langmuir adsorption isotherm gave the best-fit results out of all the isotherms studied. Theoretical studies based on density functional theory supported experimental observations. From the results, it was also observed that lower weight loss and better inhibition efficiency are achieved in the case of ferrite–bainite when compared to the ferrite–martensite structure. Surface characterization confirmed corrosion and inhibition on the surface of the metal as the surface became uneven when exposed to a corrosive medium and smooth when immersed in the inhibited solution.

Weldability of austempered rail steel using the flash-butt process

In this study, bainitic microstructure was formed via heat treatmenton R260 rail steel, which is generally used in railways. Bainitic steel, which is considered more advantageous than current rail steel, waswelded by flash butt welding, which is often used for joining rails andthe mechanical and microstructure of the samples were thenexamined and compared. Bainitic structural steel obtained by austempering heattreatment with normal rail steel was welded by flash butt welding. Flash-butt welding parameters were kept constant during the experiment. The welding capabilities of the joints were compared and the results wereevaluated. It was determined that the bainite structure obtained as a result of austempering heat treatment changes the microstructuralproperties of the samples and affects the mechanical values ​of the joints.

Microstructure and Mechanical Properties of ER70-Ti Steel for Gas Shielded Welding Wire

In this paper, ER70-Ti welding wire steel produced by an enterprise was used as the test material. The final rolling temperature was set at 960 °C, 930 °C and 900 °C, and the spinning temperature was set at 880 °C, 860 °C and 840 °C. The results showed that the microhardness of the steel decreased from 303HV to 248HV and from 317HV to 276HV as the spinning temperature decreased from 880 °C to 840 °C. The microstructure and mechanical properties of the wires with the diameters of 5.5mm, 4mm, 2.5mm, 1.4 mm and 1.2mm were examined. It was observed that the microstructure of each sample had bainite and ferrite dual phase structure. With the decrease of wire diameter, the strength gradually increased and the ductility decreased. The experimental results show that the existence of bainite structure in the welding wire is the main reason for the high strength of the welding wire and easy fracture in drawing. Based on this, the final rolling temperature of 900 °C and the spinning temperature of 840 °C should be adopted in the production of ER70-Ti welding wire steel.

Features of the ferrite-bainite structure low-alloy low-carbon steel after heat hardening and subsequent tempering

Problem statement. In recent decades, there has been a tendency to increase the mechanical properties of low-carbon, low-alloyed steel plate iron by using controlled rolling or hardening heat treatment of finished steel parts. At the same time, for welded parts, the most suitable is a metal having a ferrite-bainite (or bainite) structure. The work investigated the features of the ferrite-bainite structure of low-carbon and low-alloyed steel 15ХСНД for the production of connecting pipeline parts. Purpose of the article. To establish the laws of formation of a ferritic-bainitic structure in low-carbon low-alloy steels depending on the parameters of heat treatment. Determine the effect of heat treatment parameters on the properties of the connecting parts of pipelines made of these steels. Conclusion. The regularities of the influence of heat treatment parameters on the structure, mechanical properties and topography of fractures of impact samples of 15ХСНД steel with a ferrite-bainitic structure are established. Keywords: stamped-welded connecting parts of man pipelines; heat treatment; microstructure; bainite;mechanical properties; fractography

Corrosion Behavior of a Predeformed Fe-Ni Lateritic Steel with Bainite Structure

In a railway track for intermodal usage between a train station to a port, an observation on corrosion behavior of the track alloy in the coastal environment needs to be considered. In this study, Fe-Ni lateritic steel with bainite structure is observed. This alloy is developed from lateritic ores in Indonesia as an alternative to the conventionally made Fe-Ni steels. This study aims to determine the effect of cold rolling and austempering processes on the corrosion properties of the alloy. The cold-rolling reductions used are 30% and 70%, followed by an austempering process at 400°C for 30 mins with air cooling. The corrosion test was performed on four different samples-- First, a before deformation sample. Second, 30% and 70% cold-rolled samples. Third, austempered without deformation samples. Besides, fourth, deformed austempered samples. The corrosion test method implemented was the CASS Method for 2, 4, and 6 days. The highest corrosion rate obtained by 30% cold rolling, and the corrosion rate is increased as the austempering addition. The microstructures of rust are approximately porous few compact, near to voluminous coarse-grain corrosion products, and tend to crack.

Effect of Austenization Temperature on the Microstructure in Cr-Mn-Si Steel

This work is a part of research on the microstructure and mechanical properties of Cr-Mn-Si steels after various thermal treatments. In order to increase the resistance of the materials against failure it is necessary to possess simultaneously high strength and plasticity at the same time. Normally, in conventional metals, this is impossible. The purpose of the present study is to trace the polymorphic transformation of the microstructure and the redistribution of the trace elements in the corresponding microstructural transformations of the steel at each stage of applied heat treatment - austenization, quenching, austempering, tempering. The chosen sequence of applied heat treatments is to obtain a bainite structure of up to 50% in order to achieve high strength and toughness of the material.

Effects of strain aging on fracture of low-alloy steels with different structure

Low-alloy shipbuilding and pipeline steels are commonly subjected to thermomechanical treatment in order to form a ferrite-pearlite or ferrite-bainite structure. At the same time, a high density of lattice defect appearing in this treatment results in some structural instability fraught with the following aging in the production cycle or during the storage and exploitation. The present paper considers effects of the strain aging on steel fracture mechanism as well as efficient ways to reduce such effects.