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Atomic Diffusion Additive Manufacturing (ADAM) is a recent metal sintering process based on known composite printing technology. ADAM can be classified as indirect additive production using fibre of metal powder bound in a plastic matrix. The plastic binder allows the metal powder to remain in place when is printing. Thus, a "green part" is printed and then the plastic binder is removed by the post-washing and sintering process. The aim of this work is providing a brief description of the ADAM process patented by Markforged. Furthermore, the main task was to compare the technology with other sintering technology, namely SLM technology. It works on the basis of selective bonding of metal powder using the thermal energy of the laser beam. Parameters, such as dimensional and shape accuracy, roughness of printed surfaces or tensile strength of printed samples were examined and compared. Dimensional accuracy of the ADAM process was evaluated using ISO IT grades - determined on the basis of the reference standard. The observed accuracy of the sintering process was comparable to traditional production processes.

Superalloys are a group of alloys developed for use during long-term heat exposure above 650 °C. Properties and applications of superalloys are described in the present work. The work includes statis-tics about superalloys demand, market value and the current price. Division of superalloys according to basic element is mentioned. Nickel-based superalloys are further divided into two groups accord-ing to their use. Afterwards, the paper is focused mainly on nickel-based superalloys. Examples of nickel-based superalloys are listed in the work. Recycling possibilities of nickel-based superalloys are stated and analysed. General scheme of processing nickel-based superalloy scrap with regard to the content of rhenium is proposed and shortly discussed. The best-known companies dealing with sup-eralloy scrap recycling are mentioned further.

At present, electromagnetic induction quenching and nitriding are two commonly used surface strengthening approaches applied in improving the strength of the steel parts. In this paper, a comparative study was proposed to research the strengthening effect of these two technologies in improving the fatigue strength of steel crankshaft. First a modified statistical analysis approach of the fatigue limit load was proposed to obtain the distribution of the fatigue limit load. Then two types of steel crankshafts were selected to be the object of research and treated by these two techniques. Finally the standard T and F hypothesis testing methods were conducted in evaluation the strengthening effect. The results showed that compared with the nitriding approach, the electromagnetic induction approach can improve the fatigue strength of the steel crankshaft more obviously, thus is more suitable for engineering applications.

Polyvinyl butyral is a material that is widely used in the manufacture of laminated glass sheets. Polyvinyl butyral film is widely used as an intermediate layer for laminated automotive or architectural glass. The intermediate layer primarily ensures the safety function of the laminated glass. Other advantages of laminated glass with a polyvinyl butyral interlayer include that it can be adapted to perform other functions, including acoustic functions, anti-reflection functions or functions enabling information to be projected on the glass with this interlayer. In this work, the influence of further processing of polyvinyl butyral film with non-uniform thickness is studied. Further processing may have a negative impact to the profile of PVB material.

This paper focuses on the issues of tool thermal deformation during machine preheating，designing an image-processing-based solution for measuring these tool thermal deformation, to obtain the axial thermal error of the tool as a function of preheating time.This paper uses a high-speed camera to collect images of tool thermal deformation. Using MATLAB software, rough localization of images by Canny algorithm for edge extraction. Accurately locating tool edge outlines using a sub-pixel fitted edge detection method, that is, using the least squares method to fit a tool tip arc curve. From this, the thermal deformation during tool preheating is calculated. This study will serve as a basis for the compensation of thermal errors in machine tools.

After the Fukushima accident in 2011 year, ATF nuclear fuel cladding concept was accelerated to achieve the reactor operation with the new accident tolerant structural materials. However, several designed solutions do not fulfil the accident tolerant concept but particularly increase the corrosion resistance of Zr-cladding tubes at normal operating conditions, so-called “Advaced Technology Fuel, EATF”. Cr-coated zirconium claddings following the first concept, have been the widely tested and the first full Cr-coated fuel rods have been planned to operate in LWR reactor conditions around the 2022 year. Our contribution describes the Cr-coated Zr-%1Nb cladding tube microstructure after high-temperature steam oxidation at 1200°C by means of Scanning Electron Microscopy and nanoindenta-tion methods. The article is focused on WDS line-profile studies of oxygen and chromium diffusion into the Zr-matrix. The increased Cr-diffusion with oxygen is evident causing a change in local me-chanical properties which is well-described by measurements of nanohardness and Young's modulus. In addition, the developed methodology of the WDS & nanoindentation line-analyses was also opti-mized to apply in hot-cell conditions to measure the effect of neutron-irradiation on the different coat-ings and coating/matrix interface.

This study is focused on testing the ballistic resistance of composite materials to define their limit thicknesses according to the US STANDARD NIJ 0101.06, level III. The materials Twaron CT 747, Twaron CT 747 TH110 and Endumax Shield XF33, which are widely used in the manufacture of the ballistic protection systems, were tested. A method known as the Taylor Anvil Test (TAT) was used to verify their ballistic resistance. The missile 7.62 mm M80 was used to test the ballistic resistance of these materials. Within the experimental part, the deformation processes of composite materials were examined after impact by this missile. The value of the traumatic effect according to the US STANDARD NIJ 0101.06 was also measured. The results of the experiment provide an idea of the ballistic resistance of selected materials. Based on the results, TAT proved to be the perspective measurement method for further development and optimalization of the multilayer composite armor.

The article deals with the wear of the blades of the delimber device of harvester head. An input analysis of the materials of the fixed knife and movable arm parts was performed. It consisted of chemical analysis, evaluation of microstructure and hardness measurement by HRC and HB methods. The original welded joint was analyzed, which ensured the connection of the blade and the fixed, resp. movable arm mechanism. Based on the findings, two blade replacement solutions have been proposed. The first was the application of hard metal by an OK 84.58 electrode and second use HARDOX 450 by welding with a fixed part or a mechanical gripping with screws. This was recommended based on previous research at the Faculty of Technology. The hardnesses of the original blade material were compared with the proposed solutions. The correctness of the proposed methods will be verified in the future and in operation.

Leading manufacturers and sellers of products in the field of rolling bearings for the automotive in-dustry guarantee their quality. Extensive product testing is required to guarantee quality. When test-ing wheel bearings, bending fatigue test stations are used, among other things, to verify the strength of components. The content of the presented work is the analysis of the effect of bending moment on the temperature of a newly wound wheel bearing of the 3rd generation, based on experimental measurements. These are dynamic tests of the strength of wheel bearing components at a resonant test station. This verification is very important and has the effect of preventing the start of mass pro-duction of components that do not meet the basic safety requirements.

Providing products with higher quality and lower prices is considered to be a competitive advantage for the industrial firms over competitors. This main challenge can be achieved by minimizing the overall production costs and operational time. Lean manufacturing provides many tools and techniques to iden-tify and eliminate wastes and to reduce costs in production systems. In this paper, single minute ex-change of die (SMED) technique is used as a lean manufacturing approach in a leading Palestinian aluminum profiles company. SMED was implemented through real experimental procedures applied to the extrusion line processes to investigate its effect on decreasing the setups time and improving the Overall Equipment Effectiveness (OEE) of the extrusion machine, in addition to introduce a guide for practitioners to improve the extrusion process dies exchange in similar industries. Overall, the successful implementation of SMED resulted in an increase of OEE by 3.26% as the consequence of the increase of machine availability by 4.86%.

This paper focuses on the technical and practical aspects arising during the process of window production. One of the phases in the window manufacturing process is welding PVC corners. Therefore, the main subject is flexural strength of PVC welds in the context of the required quality. In the first part of the paper, the authors highlighted the factors and conditions of the welding process and their influence on the final properties. In the next part of the study attention is mainly paid to the temperature control, which is often the cause of quality problems with welding corners. The welding process was conducted with the use of three types of welding machines, i.e. single-, double- and four-head units. In each case, the welding temperature was set in the controller of the machine; at the same time, the contact temperature measurement was taken. The next step was verification of the influence of temperature on the welded PVC corners by measuring the bending force according to PN-EN 514:2002. Additionally, the authors present the DIC (Digital Image Correlation) method used to assess displacements and strains for a selected case in the process of bending PVC corners. The study provides a basis for discussion and remarks about practical advice and identification problems associated with the durability of PVC welding in industrial processes.

The surface created by machining significantly affects the service life and functional reliability of the component. As part of this study, four different chip machining technologies were evaluated on the surface texture of the polymer material Ertacetal C. The samples were processed by turning, milling, grinding and polishing technologies, 5 samples for each technology. Within the given technology, different cutting conditions were chosen to compare the effect of cutting conditions on the resulting surface roughness. The machined surfaces were comprehensively evaluated on the basis of 16 profile and surface roughness parameters due to the practical use of the tested material. Surface texture measurements were performed on a Talysurf CCI Lite device. A non-contact method using a coher-ence correlation interferometer was used for the measurement. The obtained data were evaluated using TalyMap Platinum software. Graphical documentation of the machined surfaces was made using an Olympus DSX500 opto-digital metallographic microscope.

This article deals with nanoindentation analysis of welded overlay layer of Inconel 625 alloy on 16Mo3 steel and their interface (transition zone). The microstructure of weld metal is analyzed, as well as the weld-on steel and subsequently nanoindentation properties (nanohardnes, reduced modulus of elastic-ity) of selected structural components. The weld of Inconel 625 alloy is realized on a tube made of 16Mo3 steel, which is bent by the so-called critical bending (d≤0,7D). The article also deals with the change of investigated properties of the weld after that bending. The samples prepared from the areas with highest compressive and tensile load after the tube bending on outer, respectively inner bend arc were used for the research. Nanoindentation analysis was performed with using a Hysitron Triboin-denter TI950 and its evaluation software Triboscan.

The conventional solid-state friction welding process involves imparting a movement to one of them, bringing them closer together so that there is friction from the clamping force. By overcoming the frictional resistance on the surface of the workpieces, work converted into heat is generated. The obtained heat heats the elements to a temperature close to the melting point but not exceeding it. After stopping the movement in relation to each other, the process of pressing the elements with the force P with a greater force causes plasticization of the material and the formation of a flash. In low pressure friction welding, most of the heat required for the joining process comes from the induction coil. This means that two key process parameters such as friction time and contact force are significantly reduce. This affects the course of the process and the end result of the process of joining materials. The shape and size of the flash as well as the size of the heat-affected zone in the weld will change. Among the many advantages of this method of joining metals, one should mention the possibility of welding smaller parts, thin-walled, with complicated geometry, which the friction butt welding process would not be able to cope with. Additionally, there is a possibility of heat treatment. In order to verify the feasibility of the friction welding process with low pressure in industrial conditions, a number of tests presented in this study were carried out, together with the analysis of the results. A number of proposals for the optimization of low-force friction welding with the use of artificial intelligence have also been developed has also been developed. A simpler but less effective solution is application of neural networks. It is possible due to multiple digital recording and process automation parameters with digital recording and process automation This solution approach is not as productive as the proposed hybrid algorithm combining neural networks, fuzzy logic and genetic algorithmsThe hybrid method enables you to take advantages of all three algorithms in the position optimization.

The continuous development of construction due to the great needs of society and industry, the need to build newer and more durable buildings have meant that scientists all the time look for new opportunities to improve the quality of materials used in this field. Above all, concrete, as material commonly used in construction, has been the subject of research for many years in order to improve the properties. Already in antiquity there were the first attempts to modify the building material with fibers. Initially, they were organic fibers. However, the first patent dates from 1874, when A. Bernard patented the idea of strengthening concrete with steel filings [1]. Then, attempts were made to strengthen the concrete with long steel fibers, which was done by H. Alfsen in 1918. Further researches led N. Zitkiewic to test the strength and impact toughness of concrete with the use of pieces of mild steel wire [2]. Steel fibers in concrete were used for the first time by Romuladi and Baston in 1963. In the paper a comparative analysis of selected mechanical properties for concrete and fiber-reinforced concrete, e.g. compressive strength and Young's modulus, was presented. It was checked how the value of Young's modulus and the compressive strength of concrete change depending on the content of steel fibers. Three types of samples were tested: 1 - concrete, 2 – fiber-reinforced concrete containing 0.25% of steel fibers, 3 – fiber-reinforced concrete containing 0.50% of steel fibers. As the analysis has shown, the greater number of steel fibers is not directly proportional to the increase in its compressive strength or the value of Young's modulus.

The presented article deals with the determination of selected mechanical properties of additive ma-terials used for 3D printing (PETG, PLA, ABS, ABS +, PLA ESD, ASA, PC / ABS). Due to the fact that 3D printing has exploded over recent years and additive manufacturing has become popular in some industries, the quality of input materials and their mechanical properties is extremely im-portant. We used 3D printer Original Prusa MK3 to prepare samples for testing. Individual samples printed from all above mentioned materials were analyzed using selected mechanical tests (static tensile test, hardness tests). In the static tensile test, selected parameters (tensile strength limit, ten-sile modulus, elongation) were determined for all additive samples, which were statistically pro-cessed. The parameters for two methods of measuring hardness were also statistically evaluated, namely Shore and ball indentation. All tested additive materials were compared with the aim of ob-taining the final ranking (point evaluation of tested materials with quantification of price costs). The best properties after the performed tests were achieved by the additive material PLA Filament Plasty Mladeč.

Nowadays the electromagnetic induction quenching approach has been widely applied in the surface treatment process, especially for the parts made by metal materials such as the crankshafts. In this paper, quantitative study was adopted in researching the strengthening effect of this technique. First the multi-physics simulation was achieved to carry out the key information caused by this approach such as the temperature and residual stress distribution property. Then the fatigue limit load prediction was conducted based on the simulation results and the theory of critical distance. Finally corresponding experimental verification was performed to check the accuracy of the predictions. The results showed that the combination of the critical point method and the Goodmen mean stress model can provide highest accuracy in the prediction. While for the critical line method, the Gerbera mean stress model is the most suitable choice.

Today, the emphasis is on the production of materials that are degradable in nature and on produc-tion with modern technologies. In order for these materials to find a suitable use, they need to be exposed to the conditions that may arise in the application. The effect of degradation was assessed for composite materials with a PLA matrix and a natural-based filler, which were processed by 3D printing technology. The progress of degradation in the climate chamber was monitored over a peri-od of 6 weeks. The results are determined by static tensile test and hardness test and the difference in weights of the test bodies. The test results confirmed. During the degradation process, the test spec-imens with natural fillers deformed less than the specimens made of pure PLA. The maximum ten-sile strength values for the material with natural fillers were approximately two thirds lower than for pure PLA. The maximum tensile strength during degradation showed an increasing or stagnant ten-dency. the maximum elongation decreased during degradation for the material with fillers showed a logarithmic behavior compared to pure PLA with a linear tendency.

The article deals with the use of SPC tools to manage and improve the machining process - drilling furniture elements. The content of the article is to use such SPC tools as basic statistical parameters, box plot, histogram, classic and special control charts, and process capability indicators to assess the drill-ing process and to indicate areas to improve. The article indicates the power of SPC tools in woodwork furniture process control and power of using the Statistica program from TIBCO Software Inc. in this area. SPC tools bring a lot of important and useful information about the analyzed drilling process, its weaknesses, which contributes to the improvement of the process. The conducted study has been shown that the tested drilling process requires improvements, in particular in the area related to the machine and man. The activities that should be implemented to improve the quality of the process were defined, including implementation of the Poka-Yoke system, development of a maintenance inspection schedule, a visual manual for machine setup, employee training with a verification exam, introduction of an employee's suggestion system, modification of the company's motivation system. SPC tools helped to identify the source of process problems, defined a process’s stability and capability to meet a customer requirement, and assist with other insights, that were used to define improvement action.

The topic of the article is to compare the mechanical properties and define the differences in the degra-dation process for anticorrosive glass fibres type AR and for glass fibres type E after influence of the alkaline environment in the geopolymer composite. The ongoing reactions between glass fibres and al-kaline environment lead to the dissolution and slowly decomposition of the fibres and consequently to the loss of the mechanical properties of the composite. Corrosion of glass fibres is characterized by weight loss, change of fibre diameter, reduction of mechanical properties and formation of mineral in-crustations on the surface of the fibre, which gradually leads to the formation of a continuous corrosion coating so called corrosion shell. Scanning electron microscopy was used to monitor the morphology of the fiber surface, and image analysis methods were used to evaluate morphological changes. Tests of mechanical properties (fibers - tensile test, composite materials - three-point bending and Charpy test) were used to confirm ongoing degradation processes due to the long-term influence of the alkaline envi-ronment on both types of glass fibers.

This paper deals with the topographic evaluation of samples made from materials applied in biomedicine. Different samples were made from Ti, TiAlV, TiNb and austenitic steel – Fe were used together with different surface morphology created. These samples were coated with a layer of TiNb alloy. The goal was to measure surface roughness in individual samples of biomaterials and to evaluate a 3D measurement of surface morphology made with a confocal microscope. Another task was to compare with appropriate software the pictures of material topography acquired at lower and higher magnification. Lower (10x) and higher (200x) magnification was used. For measured data evaluation SPIP and Gwyddion software were used. The same method of surface treatment was used but on different samples, which can lead to different results. The values obtained from topography measurements are crucial, but their formulation or evaluation can be affected by different processing methods. Our interest was to find and record the theoretically best procedure for the evaluation of measured data. Then to better understand the cell adhesion and integration of bacteria, we dealt with visualization of topography of given samples.

The article describes problems of welding heterogeneous welds be specific of heat resistant steel X15CrNiSi20-25 with cobalt alloy Stellite 6. Heterogeneous welds are produced by GTAW (141 according to standard EN ISO 4063) welding method. The major goals of the experiment were performing preliminary welding specifications (pWPS) for a specific welded part. Further was necessary for this weldment set parameters on mechanical testing.

The article is devoted to a comprehensive analysis of the coating of a component from the Ford Fo-cus 1.0 l EcoBoost engine. It is one of a pair of materially identical aluminum gears connected by a drive pulley and a drive. Aluminum gear components are surface treated with a mixture of metal powders using PVD technology, where the goal of the coating is to increase the hardness, abrasion resistance and heat of the base material. The chemical composition of the basic material of the gea-red aluminum drive wheel of the FORD engine proves that it is a component made by thermofor-ming and corresponds to the alloy EN AW 6061 (AlMg1SiCu) according to the standard ČSN EN 573 1-3. The microstructure of the base material component exhibits fine intermetallic phases evenly dis-tributed throughout the cross-section of the base base material, without the occurrence of larger inc-lusions and/or porosity. The cross-sectional microstructure in the area of the coating demonstrates that the component has a continuous uniform surface layer of the coating formed without a defect and does not have a diffuse bond with the base material. The measurement of the coating thickness of the component shows a continuous surface layer formed by powder metallography, which ranges from 70.1 µm to 143.9 µm. The surface EDS of the surface proves that it consists of deposited tungsten carbides produced by powder metallography and the bonding material is cobalt. Area EDS analysis of the surface coating identified morphologically two distinct areas of dark and light, where tungsten carbides and cobalt are based, and only the tungsten carbide and cobalt carbide contents change. The oxygen and carbon content also changes in the dark and light areas.

This article deals with the calculation of pressure vessels for beer maturation using analytical calcula-tion according to ČSN standards and with the help of commercial software PVESS. The article pre-sents commonly used procedures in the design of pressure vessels, resp. vessels for use in the brewing industry in the assembly of pressure vessels stacked on top of each other. The article describes the main parts of the brewery tanks, including the procedure for their design. The choice of materials used, the choice of basic dimensions of pressure vessels was determined in the work. The tank vessel is made of stainless steel 1.4301 or 1.4541. The advantages of this material in the brewing industry are also presented. From the given input parameters, a control calculation of the strength of pressure vessels was performed. The result of the work was the verification of the calculation, finding out the deviations of the measurements using mathematical software with a common calculation according to the valid standards for the calculation of pressure vessels.

The article presents new possibilities of simulation software and its application to improve the pro-duction structure. In many enterprises, the basic issues are related to the determination of planned tasks for individual positions, calculating the demand for employees, taking into account their skills and qualifications, calculating work costs, determining work efficiency and its dynamics. Therefore proper work organization consists in setting the course of work in such a way as to obtain maximum results with the least amount of work by man and machine. The article presents the problem of per-sonnel allocation to the production line. The basic stages of developing a simulation model of this process are discussed, including all necessary information and inputs. The results shows impact of the selected simulation scenarios to the workload level of the staff and the duration of the production process. In this concept, to solve the problem a simulation model of the production process was built. A new generation of 3D FlexSim simulation environment with an integrated OptQuest optimi-zation module was used.

Very dynamic development in the field of computerization and industry robotization, as well as an im-plementation of the Industry 4.0 assumptions are the main reason for the increased demand for magnetic materials. The limited rare earths availability and the sustainable development in the field of material engineering indicate that the methods of recycling magnetic materials from Waste of Electrical and Electronic Equipment are necessary. This paper presents the impovement stages of magnets recovery process - extrusion process of magnetic scraps/particles with polymer (magnetic scraps and particles obtained from WEEE). The process is developed based on the Process Failure Mode and Effects Analy-sis. The reserch pointed the irregularities, that pose the greatest risk of failure in the process. The paper presents changes in the process based on the values of the indicators: severity (S), probability of occur-rence (O), probability of detection (D) and the Risk Performance Number (RPN). Based on the PFMEA, 5 operations were added to the process. Due to changes in the process course, it is possible to minimize the effects of the irregularities occurrence.

Marine ships engines are kind of huge diesel engines. In fact, the manner of controlling the speed of a ship can impact badly on the financial matters of the machinery operation. Thus, controlling the speed of the marine engines can avoid ships to face dangerous accidents. In purpose to prevent such kind of damages, marine systems simulator have been widely used as numerical tools. In fact, the simulation of speed control systems makes it possible to render the process of controlling the speed of an engine economical and eliminates many risks. In this article, we first present a mathematical formulation to illustrate the rotational velocity process of a ship model's marine diesel engine as well as its PID controller. Secondly, we introduce a novel python's marine simulator which includes a PID controller to govern marine ship model's engines and we compare its results with another PID diesel engine speed controller that we modelled, designed and simulated via Matlab/Simulink. Results of scenarios and experiences which we carried out have shown that the response of the speed control system when using python can be accurate and close to the one of Matlab/Simulink.

CFRP (Carbon Fiber Reinforced Polymers) are often used when designing parts that need to be stiff, light and thermally stable. These benefits are a big motivation to use CFRP in many applications, one of them could be sports optics. However, optical devices require precise dimensions with tight tolerances for the opti-cal assembly to work correctly. In order to determine if CFRP could be a suitable material of choice for sports optics a simplified body of binoculars was designed. The main purpose of this prototype was to prove the possibility of using CFRP in binoculars. The tubular body was manufactured by prepreg lay-up into a 3D printed mold, followed by curing in an autoclave. After the prototype was manufactured 3D measurements of the tube using 3D scanner GOM ATOS were made. As expected, shrinkage of the mold and the epoxy resin in the matrix of CFRP caused minor deformations. However, if the shape of the cured part remains unchanged during conditions similar to the general use of binoculars, then the initial deformations happening during manufacturing could be accoun-ted for when designing the part. Other than the carbon part itself, the bond between metal and composite components is another potential point of failure in terms of desired precision. Because of that measurements and tests of concentricity of ad-hesive joints are being currently performed. The results of these tests and others that will follow will indicate if composite materials could be used as a structural material for sports optics.

The article presents the results of the use of quality instruments – tools and techniques – in order to reduce surface defects of steel structures on the example of a selected element – engine cover of asphalt milling machines. The article shows the potential of using selected quality tools – basic and new – in the service of quality analysis and improvement. Quantitative analyzes were presented out using the Pareto-Lorenz diagram and the c control chart, qualitative analyzes using the Ishikawa diagram and the FMEA method, quantitative & qualitative analyzes using the interrelationship diagram and matrix diagram, and it was proposed quality improvement using qualitative tools such as affinity diagram, and PDPC diagram. The most common defects of painted surfaces turned out to be improper thickness and surface contamination. As it has been shown, the experience of employees is largely responsible for the cause of these defects, which was also confirmed by other analyses carried out with the use of quality tools. The training was the most frequent method of prevention. It has also been shown that special attention should be paid to quality control, its effectiveness, and quantity. The article proves that correctly used quality tools can contribute to the improvement of the quality of manufactured products, helps in solving various quality problems.

This paper deals with the comparison of two tool steels M390 and M398 produced by powder metallurgy of the MICROCLEAN type. The primary use of steel is in the plastics industry to produce screws for injection moulding machines. The main purpose of the paper is to analyze the hardness after different stages of heat treatment. The first part of the article evaluates the hardness of steels after hardening, which was performed using a hardening dilatometer DIL805A. A total of 8 different controlled cooling measurements were performed, for both types of powdered tool steels, from a maximum rate of 100 °C/s to a minimum of 0.01 ° C/s. Based on the results of the first set of samples from the hardening dilatometer, the optimal cooling time is evaluated to achieve the highest hardness of both materials. This rate was used to heat treat a second set of samples that had undergone a quenching process from which a selected group was quenched to -78 °C. Freezing was performed to reduce the amount of residual austenite. Before measuring the hardness, the samples were tempered at temperatures of 200, 400, 600 °C for 2x2h. The measured hardness values were then compared with data from the manufacturer BÖHLER.