Vpliv podhlajevanja na lomno žilavost martenzitnega nerjavečega jekla AISI 420

Cryogenic treatments have been employed over the last three decades in both tool and high-alloy steels to improve wear resistance, mainly through the transformation of retained austenite and the precipitation of fine carbides. The application of these treatments to low-alloy steels and even to non-ferrous materials is becoming the subject of several investigations, due to their potentiality to reduce wear.The objective of the present work is to characterize the wear behavior of a cryogenically treated low-carbon AISI 420 martensitic stainless steel, by means of pin-on-disk tribological tests. Wear tests were performed according to ASTM G99 standard, under a range of applied normal loads and in two different environments, namely a vaseline bath and an argon atmosphere. Wear tracks were analyzed by optical microscopy and scanning electron microscopy (SEM) to evaluate wear volume, track geometry, surface features and the tribolayers generated after testing.In this study, it has been experimentally demonstrated that cryogenically treated specimens showed a wear resistance improvement ranging from 35 to 90% compared to conventionally treated ones.Obdelava s podhlajevanjem v zadnjih treh desetletjih, tako za orodja kot za visokolegirana jekla, pomeni izboljsanje njihove odpornosti proti obrabi, predvsem zaradi preoblikovanja zadrzanega avstenita in zgoscevanja finih delcev. Kakorkoli ze, izbolj{anje enega materiala je pogosto, vendar na racun drugega, zato je zanimivo oceniti ucinek takega tipa obdelave na lomno zilavost. Predmet pricujocega dela je bila dolocitev lomne zilavosti kriogensko obdelanega nizkoogljikovega martenzitnega nerjavecega jekla AISI 420, s pomocjo standardiziranih testov zlomov, izvedenih v skladu s standardoma ASTM E399 in ASTM E1820. V studiji je bilo s poizkusi dokazano, da so kriogensko obdelani vzorci pokazali hkratno povecanje KCI in trdote za 30 % in 5 %, v primerjavi s konvencionalno obdelanimi vzorci.Fil: Prieto, Germán. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca; Argentina. Universidad Nacional del Sur. Departamento de Ingeniería; ArgentinaFil: Tuckart, Walter Roberto. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca; Argentina. Universidad Nacional del Sur. Departamento de Ingeniería. Laboratorio de Estudio y Ensayo de Materiales; ArgentinaFil: Perez Ipiña, Juan Elias. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca; Argentina. Universidad Nacional del Comahue. Facultad de Ingeniería; Argentin

Wear behavior of cryogenically treated AISI 420 martensitic stainless steel

Cryogenic treatments have been employed over the last three decades in both tool and high-alloy steels to improve wear resistance, mainly through the transformation of retained austenite and the precipitation of fine carbides. In this work the wear behavior of deep cryogenically treated (DCT), low-carbon AISI 420 martensitic stainless steel specimens has been studied with respect to that of conventionally heat treated (CHT) ones. The tribological properties of the materials were assessed by means of ball-on-disk tests, under a range of applied normal loads in a paraffinic aditive-free vaseline bath. The disks were made of AISI 420 stainless steel subjected to two different heat treatments, namely, quenched and annealed (CHT), and quenched, soaked in liquid nitrogen for 2 h and annealed (DCT). A 5 mm tungsten carbide ball was used as the counterbody. Wear behavior has been characterized by wear volume, friction coefficient measurements and analyses of worn surfaces, wear debris and subsurfaces. It was found that the wear resistance of cryogenically treated specimens showed increases ranging from 35% to 39% in comparison to the conventionally treated ones.The authors appreciate the colaboration of Mr. Gustavo Montesi of the Engineering Department – UNS for his collaboration with specimens and tribometer preparation, and to the National Agency of Science and Technology Promotion for the financial assistance received (Grant code: PICT 2013-0616)

Influence of cryogenic treatments on the electrochemical behavior of two martensitic stainless steels

Cryogenic treatment is a useful method for improving the mechanical and tribological properties of a wide range of materials, especially steels. However, results regarding the effect of this treatment on the corrosion resistance are scarce, particularly in the case of martensitic stainless steels. In this research, the influence of cryogenic treatments on the properties of two different martensitic stainless steels, namely AISI 420 and AISI 440C, is investigated. Their microstructures are studied by scanning electron microscopy and X-ray diffraction and correlated with their corrosion resistance. The electrochemical beha vior of the steels is studied by measuring open-circuit potential and under experiments using cyclic anodic potentiodynamic polarization. It is found that the cryogenic treatment does not affect the pitting resistance of AISI 420 steel, but it significantly reduces the ability of AISI 440C to achieve passivation.Криогеннуа обробкуа використовують для підвищення механічних та трибологічних характеристик широкого класу матеріалів, зокрема сталей. Однак, результати, при свячені її впливу на корозійну стійкість сталей, зокрема мартенситних нержавних, нечисленні. Досліджено вплив криогенної обробки на властивості двох різних мар тенситних нержавних сталей: AISI 420 та AISI 440. Їх мікроструктуру вивчали з ви користанням сканівної електронної мікроскопії, методу рентгенівської спектроско пії та порівнювали з їх корозійною стійкістю. Електрохімічні властивості сталей до сліджували за вільного потенціалу корозії та за циклічної анодної потенціодинаміч ної поляризації. Виявили, що криогенна обробка не впливає на стійкість до пітинго утворення сталі AISI 420, але значно знижує здатність до пасиваціїFil: Flamini, Daniel Omar. Universidad Nacional del Sur. Departamento de Ingeniería Química. Instituto de Ingeniería Electroquímica y Corrosión; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Tuckart, Walter Roberto. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto de Física del Sur. Universidad Nacional del Sur. Departamento de Física. Instituto de Física del Sur; Argentina. Universidad Nacional del Sur. Departamento de Ingeniería; ArgentinaFil: Prieto, Germán. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto de Física del Sur. Universidad Nacional del Sur. Departamento de Física. Instituto de Física del Sur; Argentina. Universidad Nacional del Sur. Departamento de Ingeniería; Argentin

Influence of cryogenic treatments on the electrochemical behavior of two martensitic stainless steels

Cryogenic treatment is a useful method for improving the mechanical and tribological properties of a wide range of materials, especially steels. However, results regarding the effect of this treatment on the corrosion resistance are scarce, particularly in the case of martensitic stainless steels. In this research, the influence of cryogenic treatments on the properties of two different martensitic stainless steels, namely AISI 420 and AISI 440C, is investigated. Their microstructures are studied by scanning electron microscopy and X-ray diffraction and correlated with their corrosion resistance. The electrochemical beha vior of the steels is studied by measuring open-circuit potential and under experiments using cyclic anodic potentiodynamic polarization. It is found that the cryogenic treatment does not affect the pitting resistance of AISI 420 steel, but it significantly reduces the ability of AISI 440C to achieve passivation.Криогеннуа обробкуа використовують для підвищення механічних та трибологічних характеристик широкого класу матеріалів, зокрема сталей. Однак, результати, при свячені її впливу на корозійну стійкість сталей, зокрема мартенситних нержавних, нечисленні. Досліджено вплив криогенної обробки на властивості двох різних мар тенситних нержавних сталей: AISI 420 та AISI 440. Їх мікроструктуру вивчали з ви користанням сканівної електронної мікроскопії, методу рентгенівської спектроско пії та порівнювали з їх корозійною стійкістю. Електрохімічні властивості сталей до сліджували за вільного потенціалу корозії та за циклічної анодної потенціодинаміч ної поляризації. Виявили, що криогенна обробка не впливає на стійкість до пітинго утворення сталі AISI 420, але значно знижує здатність до пасиваціїFil: Flamini, Daniel Omar. Universidad Nacional del Sur. Departamento de Ingeniería Química. Instituto de Ingeniería Electroquímica y Corrosión; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Tuckart, Walter Roberto. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto de Física del Sur. Universidad Nacional del Sur. Departamento de Física. Instituto de Física del Sur; Argentina. Universidad Nacional del Sur. Departamento de Ingeniería; ArgentinaFil: Prieto, Germán. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto de Física del Sur. Universidad Nacional del Sur. Departamento de Física. Instituto de Física del Sur; Argentina. Universidad Nacional del Sur. Departamento de Ingeniería; Argentin

Influence of roughness on the tribological behavior of a steel- steel couple lubricated with thread compound

The purpose of this study is to determinate the influence of surface roughness on the tribological behavior of a lubricated steel against steel tribosystem. Tests were carried out at high pressure and slow sliding speed, in order to simulate at small scale, the contact conditions found in the seal of the threaded joints used in oil & gas casing and tubing strings. Tests were carried out with a simplified block-onring test, varying the surface roughness of rings between 1.3 to 3 m Ra values. A thread compound lubricant containing lead, copper, zinc and graphite was used. During each cycle of test, the normal load was varied linearly between 250 N and 7000 N. An exponential correlation between Ra and Rt roughness values with the wear damage was found and the wear damage of the blocks decreases about 40 percent with the increasing of initial Ra roughness parameter in the movil surface.Fil: Zabala, Nicolás Ariel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca; Argentina. Universidad Nacional del Sur. Departamento de Ingeniería; ArgentinaFil: Castro, Pablo Adrián. Siderca S.A.I.C.; ArgentinaFil: Tuckart, Walter Roberto. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto de Física del Sur. Universidad Nacional del Sur. Departamento de Física. Instituto de Física del Sur; Argentina. Universidad Nacional del Sur. Departamento de Ingeniería; Argentin

Tribological properties of tin and bronze coatings electrodeposited from acid baths

Electrodeposited copper, tin and bronze are widely used as protective and decorative coatings due to their good corrosion resistance and appearance. However, there are some applications in which these properties are not enough and a low coefficient of friction is required. It is known that tin has a good lubricity and that this property depends on the morphology of the deposit. Furthermore some authors have reported the use of electroplated bronze as a lubricating coating in the oil industry. The bath commonly used for the electrodeposition of this alloy is a cyanide-based electrolyte which produces high quality deposits but has several environmental problems during use and disposal owing to its high toxicity. Many cyanide free baths have been developed, either acid or alkaline, but too little information about the performance of the resulting deposits have been reported. The aim of this work is to develop an acidic noncyanide electrolyte for the electrodeposition of high quality bronze coatings and evaluate their tribological behavior.Centro de Investigación y Desarrollo en Tecnología de Pintura

Morphological and tribological analysis of synthetic and commercial sulfures

Lubrication reduces friction between two surfaces that slide over each other and prevents weldingunder high load conditions. Many lubricant bases enhance their applications by the addition ofadditives. Among them, extreme pressure (EP) additives provide properties that can withstand highload conditions, high temperature and high sliding speeds because they provide a low friction or wearinterface to make contact between the metal parts more efficient [1]. The addition of additives enhanceslubricants applications by providing specific properties suitable for enduring conditions.In this work, the morphology and tribological behavior of bismuth sulfides (Bi2S3) and molybdenumsulfides (MoS2) nanoparticles obtained by solvotermal synthesis and those used in commercialadditives were compared.Fil: Müller, Camila. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto de Física del Sur. Universidad Nacional del Sur. Departamento de Física. Instituto de Física del Sur; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Planta Piloto de Ingeniería Química. Universidad Nacional del Sur. Planta Piloto de Ingeniería Química; ArgentinaFil: Avila, Ana Julia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnol.conicet - Bahía Blanca. Unidad de Adm.territorial; ArgentinaFil: Denehy, Mariana. Universidad Nacional del Sur; ArgentinaFil: Yañez, Maria Julia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnol.conicet - Bahía Blanca. Unidad de Adm.territorial; ArgentinaFil: Ciolino, Andrés Eduardo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Planta Piloto de Ingeniería Química. Universidad Nacional del Sur. Planta Piloto de Ingeniería Química; ArgentinaFil: Tuckart, Walter Roberto. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto de Física del Sur. Universidad Nacional del Sur. Departamento de Física. Instituto de Física del Sur; Argentin

Effect of CrC-Ni on the tribological behaviour of WC cemented carbide

Abstract. Tungsten carbide (WC) is extensively used in industrial processing as cutting tools, wear resistant components and drilling tools owing to the good combination of phenomenal properties. The binder phase of WC is usually cobalt (Co) as a result of good wetting behaviour and excellent solubility with regards to WC particles. However, degradation of WC-Co components when subjected to harsh environmental conditions often results in premature failures during application. In this study, the effect of CrC-Ni on the microstructure, mechanical and tribological properties of WC based cermet produced by spark plasma sintering was investigated. Sintered samples were then analysed and characterized by SEM and EDS. Macro hardness of the sintered compacts were evaluated using Rockwell hardness machine at 150kg load. Subsequently, comparative studies on the tribological behaviour of the experimental samples were performed using a reciprocating wear set up at 200°C. The area of the wear track cross-section was measured using optical profiler and the wear rate in terms of volume loss was calculated. Results showed improved mechanical and tribological properties on WC-20CrC-7Ni sample as compared to WC-Co cemented carbide sample

Tribological properties of tin and bronze coatings electrodeposited from acid baths

Electrodeposited copper, tin and bronze are widely used as protective and decorative coatings due to their good corrosion resistance and appearance. However, there are some applications in which these properties are not enough and a low coefficient of friction is required. It is known that tin has a good lubricity and that this property depends on the morphology of the deposit. Furthermore some authors have reported the use of electroplated bronze as a lubricating coating in the oil industry. The bath commonly used for the electrodeposition of this alloy is a cyanide-based electrolyte which produces high quality deposits but has several environmental problems during use and disposal owing to its high toxicity. Many cyanide free baths have been developed, either acid or alkaline, but too little information about the performance of the resulting deposits have been reported. The aim of this work is to develop an acidic noncyanide electrolyte for the electrodeposition of high quality bronze coatings and evaluate their tribological behavior.Centro de Investigación y Desarrollo en Tecnología de Pintura

Tin Coatings Electrodeposited from Sulfonic Acid-Based Electrolytes : Tribological Behavior

A high efficiency methane sulfonic acid electrolyte used for tin electrodeposition was studied, and the properties of the resulting deposits were compared to those of tin coatings obtained from an industrial phenol sulfonic acid electrolyte. Cyclic voltammetry was used to study the effect of organic additives on the reduction process to define the composition of the electrolytic bath. Thick tin electrodeposits were obtained on rotating cylinder steel electrodes, and their surface morphology, preferred crystal orientation, surface roughness, micro hardness, and tribological behavior were measured. Smooth, adherent, and bright tin coatings were obtained from the methane sulfonic acid electrolyte, which differed in morphology and texture from tin electrodeposited from the industrial bath. Influence of organic additives on preferred crystal orientation of the coatings was found to be stronger than changing the supporting sulfonic acid type. Tribological tests showed that the two types of deposits have a similar coefficient of friction. However, tin coatings obtained from methane sulfonic electrolytes presented a lower wear resistance and underwent galling at lower loads.Centro de Investigación y Desarrollo en Tecnología de Pintura