Abstract: The application of magnetic-property oriented methods for non-destructive testing is very promising due to its low cost and robustness. This paper presents the methodology of simulating the magnetic properties of martensitic X30Cr13 steel applying the extended Jiles-Atherton model. On the basis of experimental measurements, the parameters of the Jiles-Atherton model were determined by an evolutionary strategy together with gradient optimisation. A very good agreement between experimental hysteresis loops and the model was confirmed by a high value of determination coefficient. The presented results open new possibilities of developing methods for non-destructive testing of energetic turbines made of X30Cr13 stainless steel. Moreover, quantitative simulation gives a possibility of a better understanding of magnetisation processes.
Abstract: The paper presents the results of physical modelling aimed at determining the cracking susceptibility of the selected steel grade under conditions characteristic of the continuous casting process. The material used for investigation was steel grade S355J2G3 . For a study on the physical modelling of the continuous steel casting process, the GLEEBLE 3800 [2, 3], a metallurgical process simulator, was employed. The obtained results allowed establishing conditions for a continuous steel casting process that could cause cracks to form in the material being cast. Research on one of technological conditions for steelworks was carried out taking into account the problem of cracking during rolling in the initial group of the bar rolling mill.
Abstract: Boron nitride coatings have been deposited onto high-speed steel substrates using pulsed laser deposition technique combined with RF-discharge. In order to improve adhesion and reduce internal stresses, substrates were subjected to gas nitriding. The structure and morphology of coatings were investigated applying atomic force microscopy (AFM) and FTIR spectroscopy. Nanohardness and elastic modulus were examined employing a nanoanalyzer (CETR). On the basis of the conducted experiments, stable, crystalline, multiphase coatings have been obtained. It has been proved that morphology, structure and mechanical properties strongly depend on the parameters of the PLD process; in particular, the temperature of the substrate has a crucial influence on the properties of BN coatings.
Abstract: The high demands required today by manufacturing engineers for machine parts and tools necessitate very precise machining. The finishing processes are an important perspective to be considered today for meeting the goals like parallelism, tolerances, flatness, and smooth surface. These processes are high-precision abrasive processes used to generate surfaces of desired characteristic such as geometry, form, tolerances, surface integrity, and roughness characteristics. A leading importance in this perspective has the lapping process. It leads to a surface with low roughness and high precision. The topographical structure resulting from lapping is very advantageous in sliding joints, because of the high ability of lubricant retention, as well as in nonsliding joints because of the high load-carrying ability. Many materials can be lapped, including glass, ceramic, plastic, metals and their alloys, sintered materials, satellite, ferrite, copper, cast iron, steel, etc.This paper reports the observations of steel C45 elements lapping process results. Workpieces were rollers with diameter 17 mm and height 10 mm placed in the conditioning rings with use of workholdings. Samples were divided to three groups according to their Vicker’s hardness: 160, 440, and 650 HV. After grinding, lapping process was conducted. Experiments were carried out with an angular speed of the lapping plate set at 65 RPM, and lapping velocity was v = 49 m/min. The lapping pressure was provided by dead weights and during experiments executing p = 0.04 MPa. Samples were lapped during 10, 15 and 20 minutes. Abrasive slurry was composed of silicon carbide grains mixed with kerosene and machine oil. Abrasive grains size was F400/17.The material removal rate (MRR) and specimens surface characteristic are studied in the light of workpiece material hardness. Test results show that applied process parameters are the best for steel which hardness is 440 HV. In that case, the lowest values of Ra parameter were obtained in conjunction with satisfactory values of material removal rate. It can be also seen, as could be predicted, that lapping time influenced on lapping results. MRR increases and surface roughness decreases with time. The worst lapping results were obtained for normalized steel (160HV). It can be the effect of surface damage, like scratching and grooving by harder abrasive grains.
Abstract: Haynes-25 alloy (also known as L-605 alloy) is extensively used in the applications of aerospace industry, turbine and furnace parts, power generators and heat exchangers and petroleum refining components due to its excellent properties. However, machining this alloy is more difficult compared to normal steel or even stainless one because of its characteristics of hardness and strength. This paper presents experimental investigation into machining parameters in the turning process of Haynes 25 alloy using uncoated carbide tools. Design of experiment (DOE) has been used for studying the effect of the main turning parameters such as cooling condition, cutting speed and feed rate on the arithmetic average surface roughness (Ra) of Haynes-25 alloy. Tests are designed according to Taguchi’s orthogonal array. Experiments have been performed under dry cutting and conventional wet cooling. Minimum surface roughness was obtained in turning using uncoated tools under wet cooling condition at the cutting speed of 45 m/min and feed rate of 0.12 mm/rev.
Abstract: The paper presents the results of the physical and numerical modelling of heat treatment of experimental steels for pipelines. Simulation has been conducted at the Institute of Metal Forming and Safety Engineering of Częstochowa University of Technology. The numerical modelling of heat treatment has been carried using commercial program TTSteel. Based on the results of computer simulation, changes in steel microstructure during continuous cooling have been analysed, and the characteristics of temperature and the diagram of Continuous Cooling Transformation (CCT) have been constructed. Numerical research has been verified running the physical simulation of heat treatment of steel using dilatometer DIL805 A/D. The characteristic temperature of steel and the size of the former austenite grains have been determined. Also, the metallographic examination of the samples was conducted and Vickers hardness was tested. The obtained results have been used for building a real CCT diagram of steel.
Abstract: Nowadays methods of hot-rolled sheets should ensure high mechanical and plastic properties of sheets, in-line rolling. Such technologies require application of devices for accelerated cooling of a band after last deformation. The essential thing in this process is selection of an appropriate positioning of the cooling intensity. The paper presents results of the cooling intensity for the selected air-water nozzle. On the basis of the results, the map of distribution of heat transfer coefficient for the nozzle to the surface of the cooling was performed. These tests were carried out for different settings of water and air. The research was carried out for high-strength steel. The obtained results allow executing of computer simulation of the impact of cooling intensity on the final product’s structure.
Abstract: Fused Deposition Modeling (FDM) is one of most common ways of rapidly producing a part. Heated material (most commonly – plastic) is used to extrude it through a nozzle and deposit on a surface layer by layer until the part is fully produced. FDM has become one of the most popular in rapid production area due to its low cost, available materials and versatility.Due to fact that part is made layer by layer and each additional layer is deposited on top of a layer that is already a little below material melting point, part maintains different mechanical properties in various directions. These varying mechanical properties affect the part usability in practical applications. Critical point is tensile strength.The objective of this paper is to research optimal processing parameters for FDM prototyping to improve tensile strength. Several rapid prototype models (tensile test samples) with various geometry of longitudinal reinforcement channels were built. As reinforcing material, the epoxy resin was used, because it has higher tensile strength when solid and allows filling channels with various geometry. All made samples were tested for tensile strength. Experiment was carried out to confirm the effectiveness of this approach. From the results, it is found how different amount of epoxy resin affects part tensile strength.
Abstract: The aim of this work is to improve the navigation capabilities of an off-road unmanned ground vehicle (UGV) by optimizing the angles between its legs and its body (its configuration angles), as the vehicle travels by a particular track profile. We present a numerical program based on a quasi-static half vehicle model. For a profile entered by the user, the program will be able to calculate how the angles between the legs and the body must vary along the trajectory, so that to maintain the torque on the wheels as constant as possible. Results may be helpful in vehicle control tasks, in particular when passing obstacles efficiently.First of all, some considerations concerning the nomenclature and geometry of the vehicle are presented. Then, the kinematics of the vehicle is exposed starting from the function that defines the profile. We focus on the position and/or trajectories of remarkable points to be employed later. From the kinematics, the quasi-static model is developed and the equations to calculate the forces and torques involved are presented. The algorithm basically calculates the position along the track and the angles between the legs and the body and then, by using the previous equations, finds the optimal values of those angles that satisfy a given condition (as equal to normal forces, torque constancy, minimum torque, etc.)As results, we present the configuration angles that equal to the normal forces on the wheels when the vehicle ascends a ramp, depending on the slope. We also present the optimal configuration angles variation required for the vehicle to pass over a step obstacle. And for a complex profile how the torque changes in function of the angles between the legs.
Abstract: This article presents the analysis of a possibility of application of agent-based technology in the e-manufacturing environment. The philosophy of e-manufacturing is a response to the demand of gaining the competitive advantage as a result of a simultaneous reduction of goods/materials in stock and the increase of the quality level of customer service. It consists in the complete integration of the company’s environment, i.e. the areas connected with production and the areas related to company’s administration and management. It may be done on the basis of communication applying cutting-edge IT technology with the use of intelligent IT techniques. Agent-based systems constitute a relatively new approach to analysing, designing as well as implementing scattered applications meant to be used in the dynamic environment of e-manufacturing.