Wear Characteristics of 22MnB5 Boron Steel under Friction Micro Pin-on-Disks Test

22MnB5 Boron Steel can be considered as emerged material for high strength and low weight application. This material potentially used in abrasive condition such as cutting tool or brake pad where high friction resistance applies. In this study, the wear characteristics of 22MnB5 was investigated under the frictional tests via micro pin-on-disk. 22MnB5 Boron Steel was prepared the form of round shape within the size of 2.6 mm thickness and 12 mm diameter by using laser cutting. 4 different samples were tested namely blank (sample A), self-hardening heat treatment (sample B), 60 HRC hot stamped (sample C) and 70 HRC hot stamped (sample D). The results show that Coefficient of Friction (COF) increased as the hardness of 22MnB5 decreased. Low COF of 0.2114 recorded for sample D with 70 HRC hardness. The COF increased to 0.24, 0.29 and 0.3 when sample C (60 HRC), sample B (52 HRC) and sample A (45.5 HRC) applied respectively. For pin-on disc test, worn area decreased as the hardness increased. 22MnB5 that prepared with the highest hardness of 70 HRC presented smallest wear area of 700 µm x 2400 µm. It is followed by 800 µm x 2400 µm, 1000 µm x 2400 µm, 1600 µm x 2800 µm, when sample C, B and A were scratched. Observation on the worn surface revealed delamination of 22MnB5 surface in the form of fragmented flaking debris.

Austempering and Bainitic Transformation Kinetics of AISI 52100

AISI 52100 is a high carbon alloy steel typically used in bearings. One hardening heat treatment method for AISI 52100 is austempering, in which the steel is heated to above austenitizing temperature, cooled to just above martensite starting (Ms) temperature in quench media (typically molten salt), held at that temperature until the transformation to bainite is completed and then cooled further to room temperature. Different austempering temperatures and holding times will develop different bainite percentages in the steel and result in different mechanical properties. In the present work, the bainitic transformation kinetics of AISI 52100 were investigated through experiments and simulation. Molten salt austempering trials of AISI 52100 were conducted at selected austempering temperatures and holding times. The austempered samples were characterized and the bainitic transformation kinetics were analyzed by Avrami equations using measured hardness data. The CHTE quench probe was used to measure the cooling curves in the molten salt from austenitizing temperature to the selected austempering temperatures. The heat transfer coefficient (HTC) was calculated with the measured cooling rates and used to calculate the bainitic transformation kinetics via DANTE software. The experimental results were compared with the calculated results and they had good agreement.

Investigation of the Effect of Hardening Heat Treatment Modes on the Properties of Products Made of Silicon-Nickel Bronze

Investigations of the effect of hardening heat treatment modes on the properties of specimens from the CuNi3Si alloy were carried out. The modes of hardening and temperature-time parameters of aging, which increase the operational characteristics of structural elements from the CuNi3Si alloy, have been determined. Investigations of the microstructure of the obtained samples and energy-dispersive X-ray microanalysis of the hardening phase have been carried out. The sensitivity of the hardness of the samples to the density and size of finely dispersed particles released during aging, recognized as nickel silicide Ni2Si, was revealed.

Age hardening heat treatment behavior of as-cast Mg–Zn–Al alloys

Magnesium alloys have generated renewed interest as a light alloys; replacing some conventional structural materials for weight reduction in applications like aerospace, automotive and electronics industries. In interior components and powertrains, cast alloys are widely used and represent more than 99% of magnesium alloys used today, whereas only a few wrought products are used. Mostly in automotive applications, Mg-engine block can noticeably reduce the weight and consequently its fuel consumption and environmental impact. Due to solid-state precipitates, these alloys are strong in nature and are produced by an age-hardening heat treatment process. In the present work the age hardening behavior of the as cast Mg–Zn–Al alloys (ZA85 alloy) in the composition of 8 wt. %Zn, 5 wt. %Al has been investigated. Through the differential thermal analysis (DTA) studies, it has been found out that dissolution temperature of ternary eutectic precipitates is present in the alloy. Based on the DTA results, the as cast samples have been solutionised at 360 °C temperature for different intervals of time. Solutionising time has been optimized from the enthalpy values of un-dissolved precipitates. The solution treated samples have been then aged at temperature of 180° C for different time intervals. From the peak hardness values, the ageing conditions have been optimized.

THEORETICAL AND PRACTICAL BASIS OF ROLLED PRODUCTS

The article presents the theoretical and practical basis for the production of rolled products in the conditions of a metallurgical plant. The processes of plastic deformation of bodies between rotating drive rolls are shown. The main results of research on rolled products made of rolled steel are presented. The chemical composition, mechanical properties, macro -and microstructure parameters, and strengthening treatments of locally produced rolled steel were studied. It is shown that after hardening treatment, the strength increases and the quality of rolled products improves.Keywords:composition and properties of rolled metal products, plastic deformation process, rotating drive rollers, rolled body, rolled steel, hardening heat treatment, hardness, macro-and microstructure, performance and quality of finished products

Installation of screw reduction UVO 20-50 for hardening and calibration of cylindrical parts and billets of agricultural machinery

A screw reduction unit UVO 20-50 (diameter of hardened products from 20 mm to 55 mm) with a closed cooling system for hardened rolled products with the ability to integrate equipment into a production line for manufacturing parts was developed. The UVO unit is intended for shaping and hardening of cylindrical parts by high-temperature thermomechanical treatment (HTMT) with metal deformation by screw compression (VO), ensuring the technical characteristics of products. It is known that some thermomechanical methods of hardening and production of rolled products, for example, steels HTMT, in comparison with conventional types of hardening heat treatment, provide a set of higher properties: strength, ductility and fracture resistance. Evaluating the efficiency of us-ing the hardening thermomechanical treatment of long products for highly loaded parts, it is neces-sary to use the criteria of fracture mechanics, to study the resistance to brittle and cyclic fracture of steel under the action of stress concentrators, negative temperatures and other difficult test and op-erating conditions. Taking into account the increased properties of steels with HTMT, it becomes possible to use hollow sections instead of solid billets. The investigated materials and the revealed patterns allow authors to conclude that thick-walled hollow parts, which are used to save metal and lighten the weight of structures, should be considered not only as full-fledged substitutes for solid ones, but also as having an advantage over the latter, mainly due to their better hardenability at sur-face cold working and less sensitivity to stress concentration at cyclic loads, which makes them more reliable in operation. These research results substantiate the wider use of hollow profiles for such parts of agricultural machinery as track pins, shafts, axles, torsion bars and other parts for var-ious purposes.

IMPROVING THE TRIBOLOGICAL CHARACTERISTICS OF 18KHGT STEEL AFTER CEMENTATION AND HARDENING HEAT TREATMENT

The work presents the results of the following researches: – samples of gears made of 18KhGT steel (determination of the thickness of the cemented layer, distribution of microhardness over the thickness of the cemented layer, measurement of the surface and core hardness, analysis of the microstructure of the cemented layer and core); – suspensions of grades VAP-2, VAP-4 and VFP-5 (determination of the conditional viscosity, mass fraction of nonvolatile substances, coating impact strength, coating elasticity in ben-ding, coating adhesion, hardness and density). There has been performed a comparative analysis of the tribological characteristics of solid lubricating coatings of the VAP-2, VAP-4 and VFP-5 grades on samples of steel 18KhGT after carburizing and hardening heat treatment.

PENGARUH PROSES HARDENING BAJA AISI 1045 TERHADAP SIFAT KEAUSAN

AISI 1045 steel is a steel classified as medium carbon alloy steel which is widely used as the main material in machinery so it must have good mechanical properties such as hardness, wear resistance. The purpose of this study was to determine the effect of heat treatment on the wear rate of AISI 1045 steel. The research method used was AISI 1045 steel which was given a hardening heat treatment with a temperature variation of 800ºC, 850ºC, 900ºC with a holding time of 60 minutes, followed by rapid cooling using water . after that the specimen will be tested for wear by using a standard Pin On Disc. the results of the study show that the wear value at 800ºC has an average wear value of 15.0762 mg / cm², then at a temperature of 850ºC has an average wear value of 11.33933 mg / cm² and at a temperature of 900ºC has an average wear value of 9 9488 mg / cm². In conclusion, there was a very strong influence on the use of hardening temperature variations on the AISI 1045 steel wear and the smallest wear value on the specimen given by the hardening process at 900ºC with an average wear value of 9.9488 mg / cm².