Distortion of AISI 1020 steel substrate in the process of laser cladding of E-300 powder material

The results of experimental studies to determine the effect of power during laser powder cladding on temperature deformations of the substrate at a constant cladding rate and the mass flow rate of the powder are presented. Steel 1020 was used as the substrate material, from which samples of sizes 90x90 mm and a thickness of 8 mm were made. Laser powder cladding was performed by using a wear-resistant powder E-300 on a robotic complex with an ytterbium fiber laser and a coaxial powder feed. Single tracks were applied to the sample by laser powder cladding using various parameters of technological modes. The amount of deformation of the substrate was estimated taking into account the depth of the mixing layer. The cladding mode is selected, which provides minimal temperature deformations, with maximum process performance.

Mechanical, Pure Fatigue and Corrosion Fatigue Properties of Pack Carburizing Low Carbon Steel Aisi 1020 by Using Waste Organic Materials in 3.5% Nacl

The influence of pack carburizing by different leftover organic materials was studied.Egg shell, dropping flower,orang shell mixed with charcoal, was used as refresher and its effect on corrosion fatigue of low carbon steel 1020 AISI (American Iron and Steel Institute) was studied. Carbon steel 1020 originally used for manufacturenumerousdevice parts such as gears, shaft, connecting rod.Severalsamples for the tensile and fatigueexaminationsareequipped from the based metalagreeing toASTM (American Society for Testing and Materials)descriptions. Pack carburizing is carried outby charcoal for liberation atomic carbon.The diffusion procedure on selectedsamples were pack carburizing using charcoal with addition leftover organic materialsas energies withratio of30% pack carburizing and at925 for two hours. After that, the samples quenched in water and tempered. Tensile,hardness, microstructures examination were implemented. Corrosion fatigue wascarried by rotating bending device in sea water 3.5% NaCl. The results showed that all carburizing compound causes an improving in corrosion fatigue due to the change in microstructure between the surface of specimens,its core and the comparative residual stress which produce by carburizing process.Egg shell give the high value and charcoal the lower value with respect to the basemetal.

CHARACTERISTICS OF DRY SLIDING ELECTRIC CONTACT OF METALS IN CONDITIONS OF CATASTROPHIC WEARING

The authors have studied the relation between wear intensity, average contact temperature and phase composition of the surface layers ofAISI 1020 steel, copper and NiTi alloy in dry sliding against the steel counterbody under electric current of density higher than 100 A/cm2 . These contact characteristics are considered carefully at the beginning of catastrophic wear, when the surface layers transit to the utmost state. It was noted that relaxation of stresses in the surface layers was due to the structural transformation in normal wear regime. It leads to tribolayers formation. The high strength of the copper tribolayer is first of all due to the formation of FeO oxide on the sliding surface, which prevents adhesion in contact. In addition, signs of a liquid phase were observed on the copper contact surface. It promoted the low rate of formation and accumulation of structural defects. Emergence of areas of melt and FeO oxide on the sliding surface provides high contact wear resistance. These factors, combined with the high thermal copper conductivity, have caused the tribolayer transition to the limit state at high current density and low contact temperature. The absence of oxides on the sliding surface of the NiTi alloy has caused strong adhesion in the contact, high rate of formation and accumulation of structural defects. Therefore, the tribolayer quickly deteriorates and high wear intensity and rapid increase in the contact temperature are observed with current density increase. Therefore, the catastrophic wear of the NiTi alloy begins at a temperature about 350 °C and at low current density. The sliding surface of AISI 1020 steel contained FeO oxide, therefore strong adhesion is not manifested. Formation of FCC-Fe in tribolayer of AISI steel 1020 is detected, that promotes its accelerated deterioration. Therefore, the tribolayer of AISI steel 1020 transites to the utmost state at a relatively low current density and at a higher temperature. The presented contact temperatures corresponding to the beginning stages of the utmost state of the tribolayer do not exceed 350 °С. Comparison of these temperatures with the known contact temperatures of other metals made it possible to assert that raising of the contact temperature of any metal higher than 400 °С leads to its utmost state. Therefore the characteristics of metals contact at temperatures of sliding contact higher than 500 °С is not of practical interest.

CORROSION PROTECTION OF STEEL 1020 BY FILMS OF CONDUCTORS ELETRODEPOSITATED IN METHANOSULFONIC ACID

1020 steel is widely used in the industrial sector, however it is a reactive metal and susceptible to corrosion, being necessary to use surface coatings to corrosion protect the metal in corrosive means. The polyaniline and polypyrrole are conductive polymers that have the ability to inhibit corrosion when deposited electrode in organic media. In this work, corrosion protection was investigated through polyaniline and polypyrrole films electrodeposited in methanesulfonic acid medium. The films were electrodeposited by chronoamperometry and the corrosion tests were performed by potentiodynamic polarization in aggressive sodium chloride medium. The surface of the films was analyzed by scanning electron microscopy. From the polarization it was observed that the polypyrrole film, in relation to the polyaniline film, showed better performance against corrosion. The MEV indicated that the polypyrrole film is homogeneous and adherent, while the polyaniline film showed flaws, allowing the interaction of the metal with the corrosive medium