CRTI Library

Bio-molecule as a sustainable protection against corrosion of ductile iron in acid solution: Experimental and computational studies

The present work is devoted to study the inhibition effect and adsorption mechanism of Loratadine (LRD) on cast iron in 1 M HCl. Polarization curve, electrochemical impedance spectroscopy (EIS) and surface analysis were carefully investigated to indicate the inhibition effect of LRD on cast iron in 1 M HCl. On the other hand, Theoretical study evidenced the good loratadine reactivity toward cast iron surface. Polarization curves revealed that LRD behaves as mixed type inhibitor. The inhibition efficiency increased with the increasing concentration of LRD and reached 91 % (by EIS) at 0.46 mM of inhibitor. It showed that the adsorption of LRD on cast iron surface followed the Langmuir isotherm. The value of ΔG°ads (-37.52 kJ/mol) and the effectiveness of LRD at high temperatures, suggest physicochemical interactions of LRD with the cast iron surface. A good correlation was made between some electronic properties of LRD molecules and adsorption mode. The obtained results showed that Loratadine is an efficient corrosion inhibitor for cast iron in 1 M HCl. Voir les détails

Mots clés : corrosion inhibitor, EIS, Quantum calculations, Biomolecule

Enhanced Understanding of Corrosion Performance in Lean Duplex Stainless Steel Exposed to Aging Treatment and Mechanical Stress

This paper investigates the influence of heat treatment and mechanical stress on the microstructure, magnetic characteristics, and corrosion resistance of 2101 lean Duplex Stainless Steel (DSS). Specifically, at a temperature of 750°C during the aging treatment, the emergence of the sigma phase, in conjunction with mechanical stress, leads to material embrittlement. The study explores the applicability of employing Vibration Sample Magnetometer (VSM) and eddy current testing to detect microstructural modifications and evaluate corrosion behavior. Corrosion effects are analyzed using potentiodynamic methods (PM). Notably, a robust correlation is established between the proportion of sigma phases and electrochemical parameters. The samples are subjected to a range of conditions, including untreated states, exposure to elevated temperatures, corrosive environments, and axial loading. Material responses are meticulously examined utilizing eddy current techniques. This investigation compellingly demonstrates the capacity to identify and quantify all microstructural alterations in the samples through magnetic measurements. Voir les détails

Mots clés : LDX 2101, corrosion, aging treatment, microstructure, Mechanics stress, VSM, Hysteresis Loop, Eddy Current

Fatigue-Induced Effects of Prolonged Holding Time on Corrosion in AISI 4130 Steels Welded with a Nickel-based Electrode via the Pulsed TIG Process

The maintenance of blowout preventers (BOPs) used in the hydrocarbon field requires the use of a material with good mechanical and corrosion resistance properties. In the present study, the impact of fatigue-inducing holding times ranging from 1 to 3 hours during post-weld heat treatment (PWHT) at 640°C on the electrochemical behavior and mechanical properties of AISI 4130 steel substrate overlaid with a nickel-based alloy is investigated. The overlay was achieved using the pulsed Tungsten inert gas (TIG-Pulsed) process. The results indicated that, as the fatigue-inducing holding time increased beyond 3 hours, the hardness of the substrate/surface interface decreased. This phenomenon can be attributed to the release of thermal stress resulting from the weld overlay operation. Additionally, electrochemical impedance spectroscopy (EIS) measurements were conducted in a 2.5% NaCl solution, revealing a capacitive effect in the low-frequency region due to the precipitation of a new film that modified the surface properties. In contrast, potentiodynamic tests indicated that the open circuit potential (Ecorr) became more stable or positive with an increased fatigue-inducing holding time. Voir les détails

Mots clés : AISI4130, holding time, TIG-Pulsed, corrosion, hard facing operation

Experimental study and simulation of stable phase β (mg2si) evolution during artificial aging of aluminum alloy AA6005

An AA6005 alloy that has been machined or cast can be strengthened using various aging and solution heat treatment techniques. This is called structural precipitation hardening which goes through three steps ،a homogenization at lower temperature of melting temperature, which ensures alloy solution and then rapid cooling, and finally an aging treatment at a temperature between 180°C and 220°C for our alloys. In order to optimize the time and number of heat treatments, we perform simulations of various heat treatment ranges using MatCalc software to initiate precipitation reactions → G zone. P.→ β″→ β′→β (Mg2Si). Artificial aging is used to induce the formation of the hardening phases (Mg2Si). The MatCalc software uses the mc Al.ddb thermodynamic database for aluminum alloys. The numerical results are in good agreement with the microhardness results, which demonstrate the existence of the stable β phase Voir les détails

Mots clés : simulations, AA6005, artificial aging