Conventional Shaping the Edges of Thick Steel Plates After Welding Process

The paper presents the results of theoretical analysis and experimental details of shaping the edges of thick steel plate using conventional technology. The aim was to determine the influence of holes laser cutting on the shape and technological possibilities of the steel sheet edges flanging. In this study numerous computer simulations were made in order to design a process guaranteeing obtaining a proper product. During this simulation of material flow kinematics, strain and damage criterion distributions and shaping were analyzed. On the basis of the obtained results, the analysis of limiting phenomena, which could appear during the process, was made. Experimental tests in industrial conditions according to designed technology were carried out. Good quality of specimens shaping was obtained. It was found that shaping the edges of thick steel plate after welding process is possible

Optimization of nitrogen use efficiency in cutting of austenitic stainless steel by a fiber laser

In metallurgical processes, metal sheet cutting is usually a basic technological operation that needs to be performed. All other technological operations follow the procedure of metal sheet cutting, with the final aim of manufacturing a final product. Machines used for that basic metal cutting operation shall be reliable, efficient, fast, and relatively easy to work with. While working with a laser, the authors noticed the inefficiency of cutting with nitrogen. Nitrogen bottles got empty too quickly, which caused additional costs. Inefficient, i.e., excessive nitrogen consumption requires a more frequent supply of nitrogen. During the COVID-19 pandemic, nitrogen was not always available, as suppliers shifted to manufacture oxygen bottles for medical needs. Therefore, the authors engaged in finding solutions to reduce the consumption of nitrogen at cutting. The mentioned problem was studied within the experiment that focused on the optimization of nitrogen use during fiber laser cutting, the procedure, and results of which are described in this paper. Specimens of different cutting parameters were prepared and cut to measure their roughness and burr height. The collected data were used to create a mathematical model with an ANOVA table. The experiment resulted in the determination of optimal cutting parameters achieved by the lowest possible cutting gas pressure

Selected properties of laser cladding coatings shaped using Flow drill technology

The paper presents the investigations of selected chemical and mechanical properties as well as macro- and microstructure of materials formed using thermal drilling process (Flow drill). The aim of this study was to determine the microstructure of the coatings produced using laser cladding with powder technology. The coatings were produced on the low-carbon steel using 1 kW disc laser. After modification of surface, the thermal drilling process was applied. To produce all coatings, the pure copper powder was used. In this study the laser power equal of 500, 700 and 900 W were used. The microstructure, chemical composition (EDS) and microhardness were investigation. It was found that the surface modification of low carbon steel and next conducted thermal drilling process caused change the surface properties on the hole flange. It was found that surface modification of steel using laser cladding with cooper powder and next Flow drill process contributes to the change in microhardness and chemical composition on hole flange

Selected properties of galvanic coatings shaped using thermal drilling technology

The paper presents the investigations of mechanical properties and microstructure of materials formed by thermal drilling process (Flow drill). The aim of this study was to determine the microstructure of the surface layers produced using galvanic method on the low-carbon steel after formed this layer using thermal drilling technology. The coatings of copper and nickel thicknesses of 5, 10 and 15 μm were applied. Microstructure, chemical composition and microhardness was study. It was found the possibility of forming galvanic coatings using thermal drilling technology and change in chemical composition of treated material

Vitrification vs. slow cooling protocol using embryos cryopreserved in the 5th or 6th day after oocyte retrieval and IVF outcomes.

Modifying cryopreservation protocols may be seen as a way to simplify cryobanking procedure and increase satisfying outcomes. The aim of the study was to evaluate the influence of slow cooling protocol and vitrification on IVF outcomes using embryos preserved in the 5th or 6th day after oocyte retrieval. The study compared 2 groups of human embryos underwent slow cooling protocol (n=189) and vitrification (n=58). All embryos were cryopreserved in the 5th or 6th day after oocyte retrieval. Pre- and postfreezing embryo evaluation was performed in 2 or 3 steps scale, respectively. The study evaluates the effectiveness of two freezing methods and influence of the freezing day, pre- and postfreezing embryo grading on clinical pregnancy rate. Study showed higher pregnancy rate after vitrification (50.4%) than slow cooling protocol (25.9%). Significantly higher pregnancy rate was observed, when embryo preserved in the 5th day after oocyte retrieval (50.3%) than in the 6th day (22.7%). Postfreezing embryos evaluation showed that high quality blastocysts gave nearly four times better pregnancy outcomes than the ones evaluated as poor quality, and three times better than the ones evaluated as moderate. Prospective trials are needed to evaluate pregnancy and neonatal outcomes after vitrification. The number of controlled studies concerning vitrification has not been large enough, yet

Exploring the Impact of Different Milling Parameters of Fe/SiO₂ Composites on Their Structural and Magnetic Properties

This research focuses on the production process of soft magnetic composites in the form of 3D bulk compacts made from insulated powder particles using different milling parameters, aiming to enhance their magnetic properties and to study an innovative method of the powder surface “smoothing” technique. A structure analysis using scanning electron microscopy (SEM), EDS, and optical microscopy is also included. We found out that the samples made by the innovative method have lower density values. This can be caused by a more consistent SiO2 insulation layer on highly pure iron powder particles. A correlation between the mechanical smoothing method and better insulation of powder particles can help to provide eco-friendlier solutions for the preparation of soft magnetic composites, such as less usage of reagents and more consistent coverage of powder particles with lower final insulation thickness. The magnetic properties of these compacts are evaluated by coercive field, permeability, and loss measurements. The particle-level smoothing technique in some cases can reduce the value of coercivity up to 20%. For some samples, the ball-to-powder ratio has a bigger impact on magnetic properties than surface treatment, which can be caused by an increased amount of insulation in the SMC compacts

Tribocorrosion and Abrasive Wear Test of 22MnCrB5 Hot-Formed Steel

The article presents the results of research on abrasive and tribocorrosion wear of boron steel. This type of steel is used in the automotive and agricultural industries for the production of tools working in soil. The main goal of the article is the evaluation of tribocorrosion and abrasive wear for hot-formed 22MnCrB5 steel and a comparison of the obtained results with test results for steel in a cold-formed state. The spinning bowl method to determine the wear of samples working in the abrasive mass was used. Furthermore, a stand developed based on the ball-on-plate system allows to determine the wear during the interaction of friction and corrosion. After the hot-forming process, 22MnCrB5 steel was three times more resistant for the abrasive wear than steel without this treatment. The average wear intensity for 22MnCrB5 untreated steel was 0.00046 g per km, while for 22MnCrB5 hot-formed steel it was 0.00014 g per km. The tribocorrosion tests show that the wear trace of hot-formed 22MnCrB5 steel was about 7.03 µm, and for cold-formed 22MnCrB5 steel a 12.11 µm trace was noticed. The hot-forming method allows to obtain the desired shape of the machine element and improves the anti-wear and anti-corrosion properties for boron steel

Application of Generator-Electric Motor System for Emergency Propulsion of a Vessel in the Event of Loss of the Full Serviceability of the Diesel Main Engine

Oil tanker disasters have been a cause of major environmental disasters, with multi-generational impacts. One of the greatest hazards is damage to the propulsion system that causes the ship to turn sideways to a wave and lose stability, which in storm conditions usually leads to capsizing and sinking Despite the perceived consequences of maritime disasters in the current solutions for the propulsion of oil tankers, there are no legal or real solutions for independent emergency main propulsion in this type of ship. Stressing that the reliability of the propulsion system has a significant impact on the ship’s safety at sea, the authors presented a new solution in the form of a power take-off/power take-in (PTO/PTI) system. This is the emergency use of a shaft generator as the main electric motor, operating in parallel in a situation when the main engine (ME), (the main engine of the ship’s direct high-power propulsion system that is slow-speed) loses the operational capability to propel the ship. Since one cause of wear, or failure, of the main engines is improper operational decisions, the paper shows the wear mechanism in relation to the accuracy of operational decisions. Using classical reliability theory, it also shows that the use of the proposed system results in an increase in the reliability of the propulsion system. The main topic of the paper was the use of an electrical system called PTO/PTI as an emergency propulsion system on the largest commercial vessels, such as bulk carriers and crude oil tankers, which has not been used before in maritime technical solutions. Semi-Markov processes, continuous in time, discrete in states, and which are used in technology, were also proposed as a tool describing the process of the operation of such a ship propulsion system, and they are useful to support operational decisions affecting the state of the technical condition of the engine. There are two ship operation strategies that can be adopted: the four-state model, for normal operation, and the three-state model, which operates with the occurrence of failure. For these types of models, their limiting distributions were defined in the form of probabilities. It was also demonstrated that faster than expected engine wear and the occurrence of inoperability of the main engine can be caused by wrong operational decisions made by the shipowner or crew. Using this type of main engine operating methodology, it is possible to support the decision of the engineer to stop the main engine and to subject it to the process of restoration to an acceptable state of technical condition (before the failure or during the failure in severe storm conditions), with the parallel use of the proposed electric propulsion (PTO/PTI) as an emergency propulsion, giving the crew a chance to maintain the steering necessary to maintain safe lateral stability

Application of Generator-Electric Motor System for Emergency Propulsion of a Vessel in the Event of Loss of the Full Serviceability of the Diesel Main Engine

Oil tanker disasters have been a cause of major environmental disasters, with multi-generational impacts. One of the greatest hazards is damage to the propulsion system that causes the ship to turn sideways to a wave and lose stability, which in storm conditions usually leads to capsizing and sinking Despite the perceived consequences of maritime disasters in the current solutions for the propulsion of oil tankers, there are no legal or real solutions for independent emergency main propulsion in this type of ship. Stressing that the reliability of the propulsion system has a significant impact on the ship’s safety at sea, the authors presented a new solution in the form of a power take-off/power take-in (PTO/PTI) system. This is the emergency use of a shaft generator as the main electric motor, operating in parallel in a situation when the main engine (ME), (the main engine of the ship’s direct high-power propulsion system that is slow-speed) loses the operational capability to propel the ship. Since one cause of wear, or failure, of the main engines is improper operational decisions, the paper shows the wear mechanism in relation to the accuracy of operational decisions. Using classical reliability theory, it also shows that the use of the proposed system results in an increase in the reliability of the propulsion system. The main topic of the paper was the use of an electrical system called PTO/PTI as an emergency propulsion system on the largest commercial vessels, such as bulk carriers and crude oil tankers, which has not been used before in maritime technical solutions. Semi-Markov processes, continuous in time, discrete in states, and which are used in technology, were also proposed as a tool describing the process of the operation of such a ship propulsion system, and they are useful to support operational decisions affecting the state of the technical condition of the engine. There are two ship operation strategies that can be adopted: the four-state model, for normal operation, and the three-state model, which operates with the occurrence of failure. For these types of models, their limiting distributions were defined in the form of probabilities. It was also demonstrated that faster than expected engine wear and the occurrence of inoperability of the main engine can be caused by wrong operational decisions made by the shipowner or crew. Using this type of main engine operating methodology, it is possible to support the decision of the engineer to stop the main engine and to subject it to the process of restoration to an acceptable state of technical condition (before the failure or during the failure in severe storm conditions), with the parallel use of the proposed electric propulsion (PTO/PTI) as an emergency propulsion, giving the crew a chance to maintain the steering necessary to maintain safe lateral stability

Quality Tests of Hybrid Joint–Clinching and Adhesive—Case Study

Inseparable joints are widely used in machine and vehicle construction. Hybrid joints include bonding with sheet metal clinching. This combination reduces costs as well as the time of production compared to welded joints. Tests on the samples made of DC01 sheets were carried out. A case study was conducted on four research series. For each series, the shear forces of the joint were measured. The first series consisted of adhesive bonding, and the second and third series consisted of hybrid bonding, during which the sheet metal clinching joint was developed immediately after the completion of adhesive application and after full joint formation. The last test series only includes sheet metal clinching. In the series where bonding was used, the homogeneity of the prepared joints was analysed using the ultrasonic echo technique. The shear strength of the bonded joints was 476 N, whereas the shear strength of sheet metal clinching was 965 N. For the hybrid joint, the average forces were 1085 N (for the specimens in which the lap joint was made after the joint was fully cured) and 1486 N (for the specimens in which the lap joints were made immediately after the adhesive was applied). It was discovered that the clinching of the steel sheets significantly increases the strength of the joint. The stabilisation of the joint causes better crosslinking conditions. This results in an increase in the strength of the hybrid joint