High Level Of Hardness Research Articles

Investigation of Friction Hydro-Pillar Processing as a Repair Technique for Offshore Mooring Chain Links

Repairing links of offshore mooring chains has presented a significant industry challenge, primarily arising from modifications in material properties, encompassing alterations in microstructure, hardness, and residual stress. In this context, the present work investigates the method of friction hydro-pillar processing (FHPP) applied to R4 grade mooring chain steel. Joints in as-repaired and post-weld heat treatment (PWHT) conditions were subjected to residual stress (RS) tests using the neutron diffraction technique, microhardness mapping, and microstructural evaluations. The process generated peaks of tensile and compressive stresses in different directions and hardness below that of the parent material in the softening zone. The friction zone promoted high hardness levels in the thermo-mechanically affected zone (TMAZ) with a maximum of 19% of the ultimate tensile strength of the parent material. As expected, the PWHT restored the RS and reduced the hardness; however, 4 h PWHT allowed the elimination of a hardness higher than that of the base material.

A diamond double-sided strip detector for alpha-tagging in associated particle imaging

- In associated particle imaging, neutrons from deuterium-tritium fusion are used to interrogate objects of interest. The associated particle imaging technique utilizes an alpha-tagging sensor in the neutron generator to detect the alpha particle that is emitted antiparallel to the neutron, providing neutron birth time and direction. This technique of neutron imaging and induced fission imaging can provide higher contrast image reconstructions and better estimations of fissile material mass than passive measurement techniques. The performance goals of an alpha-tagging sensor in associated particle imaging are a 700-ps timing resolution, a 0.5 mm spatial resolution, high level of radiation hardness, low sensitivity to X-rays, high signal-to-noise ratio, and survivability in the high temperature bake out of the neutron generator. Currently employed YAP scintillators are overwhelmed by the intense X-ray field in the neutron generator, requiring a new alpha tagging sensor design to be developed. We have developed and tested a diamond double-sided strip detector as a proposed sensor for associated particle imaging. Diamond is radiation hard, has a low sensitivity to X-rays, fast timing capabilities, high signal-to-noise ratio, and can withstand the temperatures of bake-out. The spatial resolution can be accomplished with a charge division readout and double-sided strip design. We measured the timing resolution of a single crystal chemical vapor deposition (CVD) diamond with a Cividec C6 charge amplifier readout by measuring the time-of-flight of 241Am alpha particles between a thin plastic scintillator and the diamond. We also fabricated a polycrystalline CVD diamond double-sided strip detector with charge division readout to test the spatial resolution of the design. We found that the detector met both the 700-ps timing resolution and the 0.5 mm spatial resolution goals (both reported as FWHM resolution).

Mechanical, Tribological, and Corrosive Properties of NbCrCx and NbCrCxNy Coatings with Various Nitrogen and Carbon Contents

CrC and NbC carbide coatings both have good mechanical properties, wear resistance, and corrosion resistance. The present study seeks to combine the two coating systems in order to further enhance their properties. NbCrCx and NbCrCxNy coatings (where x and y denote the atomic percentages of carbon and nitrogen, respectively) were deposited on SKH51 substrates using a radio-frequency unbalanced magnetron sputtering system. The mechanical, tribological, and corrosive properties of the coatings were investigated and compared. Among the NbCrCx coatings, the NbCrC61 coating showed high levels of hardness, excellent adhesion strength, and good wear resistance. Among the NbCrCxNy coatings, the NbCrC55N5 coating showed high adhesion strength and hardness and excellent tribological properties. However, for nitrogen contents greater than 16 at%, the adhesion strength was dramatically reduced, resulting in poor tribological performance. Among all of the coatings, the NbCrC49 coating showed the best corrosion resistance due to its enhanced crystallinity, high adhesion strength, moderate surface roughness, and high sp3 C-C bonding ratio.

Synthesis and Microstructure Characterization of Fe-Cr-Al Alloys Developed by Powder Metallurgy Technique with Plasma Sintering Method

Synthesis of Fe-Cr-Al alloy by powder metallurgy method was developed to produce a bioimplant material with a low modulus of elasticity. Microstructure characterization and phase identification were carried out to support the development of bone implant material research. The alloys were synthesized with the elemental composition of 16 Cr (wt%) that was added with Al in variations of 3, 6, and 10 (wt%). The synthesis was carried out by an exceptional combination of mixing and mechanical milling, cold compacting and consolidating with a special method using the APS (Arc Plasma Sintering) apparatus. Microstructure characterization and phase identification were analyzed by SEM-EDS and XRD tests. The microstructure showed relatively homogeneous fine grain with small porosity of around 80 %. Refinement of the XRD peak pattern revealed the formation of the Fe-Cr main phase followed by the Fe-Al phase with Al as the solid solution. The hardness test showed a high hardness level with a maximum for Fe-16Cr-6Al (wt%) of around 160 VHN (Vickers Hardness Number). The quantity of Fe-Cr phase and the composition of Al influenced the hardness of the alloy.

Calcium Reduction Using Variations of Thickness and Retention Time of Cocoa Shell Activated Carbon

High levels of hardness can lead to increased cases of kidney stones. Hardness levels can be reduced by using activated carbon from the cocoa rind as an adsorbent. The purpose of this research was to determine the variation of activated carbon thickness and optimum retention time in reducing the calcium content of dug well water, to determine the percent decrease in calcium ion levels at the optimum variation, and to determine the significance of the difference in the decreased in calcium levels between the treatment groups. The research method used the principle of adsorption of activated carbon from cocoa shells to calcium ions, which are activated by KOH. There were ten treatment samples with different variations of activated carbon thickness and retention time. The results showed that the thickness of activated carbon of 60 cm with a retention time of 50 minutes had the optimum ability to reduce the calcium content of dug well water. The percentage decrease in calcium levels reached 89,041 % with a decreased concentration of 234 ppm. The result of the statistical test showed a significance value of 0,05. The conclusion of the research is that activated carbon of cocoa shells can reduce calcium levels to the levels of soft water hardness, with variations in activated carbon thickness and retention time having a significant effect.

STRUCTURAL AND MECHANICAL CHARACTERIZATION OF TUNGSTEN NITRIDE COATINGS PREPARED BY DC SPUTTERING AT CYLINDER LINER

The cylinder liner is a tube that protects the piston and is a place for the combustion process. The combustion process causes continuous friction to make the cylinder liner wear out. Therefore the cylinder liner must be made of materials that have high hardness. To obtain a high hardness level, surface treatment with DC sputtering techniques is carried out. Surface treatment with DC sputtering technique for 120 minutes with variations of Argon gas and Nitrogen gas 70:30, 80:20, and 90:10. Based on the XRD test results, all treated samples contained a WN layer. The crystal structure of the raw material samples is hexagonal, and the crystal structure of all processed samples is cubic. Vickers hardness characterization shows that the raw material is 110.93 HV. While the sample treated with Ar70:N30 was 234.66 HV. The optimum hardness occurred in samples treated with Ar80:N20 with a hardness of 311.87 HV. However, the Ar90:N10 treatment experienced a decrease in hardness to 130.44 HV. Based on the results of thin film testing, WN affects the increase in the hardness of the cylinder liner material. This is evidenced by the increase in hardness in samples coated with WN.

Effect of protein concentration on thermal aggregation and Ca2+-induced gelation of soymilk protein

The concentration of protein in soymilk is a key element in the production of soy products. In this study, the thermal aggregation behavior of soymilk proteins and the properties of aggregates formed at different concentrations (33 mg/g-56 mg/g) were analyzed. Results showed that the soymilk proteins formed two kinds of aggregates which demonstrated different properties at particular concentrations. In the low concentration range (<40 mg/g), rod-like aggregates were formed. The content and size of the aggregates increased with growing protein concentration, but the morphology didn't change. Additionally, the surface hydrophobic groups, sulfhydryl groups(-SH) and electrostatic charge of the protein aggregates exposed to the outside also increased, which drastically (20%) reduced the activation energy of the Ca2+-induced gelation and led to the cross-linkage of protein aggregates to form a dense, cluster-like network structure, which facilitated the formation of gels with high levels of hardness and increased water holding capacity (WHC). At protein concentrations greater than 40 mg/g, however, the protein subunits formed aggregates, which also combined with each other along an axial direction through the hydrophobic groups and -SH on the surface, thereby forming linear or even micro-network agglomerates. In this way, the surface hydrophobicity(S0) and -SH content decreased linearly with the rising protein concentration, while the surface charge density increased, the activation energy required for soymilk gelation increased, and the protein aggregates crosslinked to form a coarse network structure with large voids. Hence, the hardness, elasticity, toughness and WHC of the gel decreased with the increase in protein concentration. This study reveals the mechanism by which protein concentration changes the gel-forming ability of soymilk, and have important theoretical reference for enterprises to select the appropriate protein concentration for soymilk preparation, or to optimize the “concentration dilution method” to meet the processing requirements of different types of soy products.

Analysis of Hardness Level and pH of Drilled Well Water in Semin Village, Semin District, Gunungkidul Regency

Water quality must be maintained so that it remains beneficial to humans and other living things, as a means of improving public health. The requirements for clean water quality have been regulated in Permenkes No. 416 of 1990 concerning Requirements and Supervision of Water Quality. The purpose of this study was to analyze water quality with hardness and pH parameters for water hygiene and sanitation used by the people of Semin village, Semin district, Gunungkidul district. The test results showed that the highest hardness level was found in sample C3 which was 228.86 mg/L and the lowest hardness level was found in sample A2 which was 89.55 mg/L. The highest pH test results were found in sample D3, which was 8.1, while the lowest pH level was found in sample A2, which was 6.5. Based on the test results, water from drilled wells in Semin village, Semin sub-district, Gunungkidul regency, is still suitable for use for hygiene and sanitation purposes.

Hydrogeochemical constraints on uranium contamination of groundwater for drinking water supplies and associated health risks

The groundwater quality of Punjab, India is of huge concern owing to the presence of various toxic contaminants that includes uranium and other trace elements. The focus of this study is to identify the hydrogeochemical processes responsible for uranium mobilization in groundwater and evaluation of groundwater quality in uranium contaminated zones for drinking, irrigation use along with associated health risks. The study was conducted using the water quality data obtained from 302 sampling locations covering the entire state of Punjab reported by Central Ground Water Board between 2019 and 2020. It was observed that around 50% of the samples were exceeding the drinking water acceptable limits for total alkalinity, magnesium, pH, and Total Dissolved Solids. Around 25% of the samples were above drinking water acceptable limit for uranium in groundwater. A comprehensive multiplicative water quality index (MED-WQI) well represented the consolidated perspective of all individual water quality parameters wherein 40 sampling locations in districts viz. Bathinda, Fazilka, Ferozepur, Jalandhar, Kapurthala, Ludhiana, Muktsar and Sangrur fall under heavily-polluted water quality class due to high levels of uranium, alkalinity, and hardness. The Piper plots and Gibbs diagram depicted that the majority of groundwater samples were characterized as Na+–HCO3−, Ca2+–Mg2+–HCO3− systems driven by rock-water interactions. Speciation analysis indicates that the dominant uranium species in groundwater of U-affected regions was primarily associated with calcium and alkalinity and exist in the form of CaUO2(CO3)32−, Ca2UO2(CO3)3(aq), UO2(CO3)34−, and UO2(OH)3−. Various irrigation indices depict that the groundwater in majority of the state, barring few districts in Malwa region, was suitable for irrigation. Further, a non-carcinogenic health risk assessment model showed association of high health risk with heavily-polluted water quality class. The results of this study would aid regulatory authorities in designing remedial strategies and frame policy actions toward groundwater quality improvement in the uranium-affected regions of Punjab.

A modified artificial neural network to predict the tribological properties of Al-SiC nanocomposites fabricated by accumulative roll bonding process

This work highlights the major influence of SiC concentration and plastic deformation on boosting wear rates of aluminum composites supplemented with SiC particles comprising varied volume fractions (0–4%). It also shows how a basic neural network model augmented with a particle swarm optimizer can forecast wear rates and coefficients of friction for complicated composites. According to the experimental findings, increasing the quantity of accumulative roll bonding (ARB) enhances SiC particle dispersion homogeneity. Increasing the number of cycles and introducing additional SiC particles helped to reduce the wear rate and increase the friction coefficient. After nine ARB cycles, the Al-4 wt.% SiC nanocomposite had the best improvement in both wear rate and friction coefficient. The same sample was also used in efforts to enhance the characteristics of hardness, and it was selected as having the highest level of hardness, which has grown by 139%. All of the generated composites evaluated at four different wear loads were able to be predicted by the proposed model with great accuracy, with determination coefficient R2 values of 0.9768 and 0.9869 for the frictional coefficient and wear rates, respectively.

Intermetallic compound and martensitic transformation in Ag/Cu co-modified Ti6Al4V alloy

Titanium and its alloys are promising materials for engine production, special pump manufacturing, and bone implants. However, the abrasion resistance and fracture toughness of Ti alloys are insufficient to withstand extreme high loading conditions and harsh environments. Surface modification is an effective way to improve the performance of Ti alloys. In this study, Ag and Cu were added to Ti6Al4V alloy through friction stir processing to modify its surface. The different ratios of the Ag/Cu powder mixture were designed to optimize the surface modification of Ti6Al4V, and the relationship between intermetallic compounds and martensitic transformation was analyzed. The martensitic transformation was induced by AgCuTi phases. The submicron-size martensite was distributed outside the AgCuTi particle, while the nano-laminar martensitic band was generated inside the AgCuTi particle. Under the co-modification of Ti alloy using Ag and Cu, the surface of Ti6Al4V alloy exhibited higher hardness (4.3 GPa) values and lower modulus (100.6 GPa), which gave the credit to the formation of AgCuTi and martensitic transformation. The alloy specimen was subjected to short heat treatment at 600 °C for 30 min to further modify the gradient structure. After the short heat treatment of the Ag/Cu co-modified specimen, a lower modulus (88.8 GPa) and a high level of hardness (4.1 GPa) were achieved. In addition, superelastic strain recovery was also enhanced, showing the further induced martensitic transformation. This work provides new insight into the surface modification of titanium alloys using the FSP method to achieve the ideal hardness and elastic modulus balance.

Application and Effect of Pediococcus pentosaceus and Lactiplantibacillus plantarum as Starter Cultures on Bacterial Communities and Volatile Flavor Compounds of Zhayu, a Chinese Traditional Fermented Fish Product.

Zhayu is a type of traditional fermented fish product in China that is made through the fermentation of salted fish with a mixture of cereals and spices. Inoculation fermentation was performed using Pediococcus pentosaceus P1, Lactiplantibacillus plantarum L1, and a mixture of two strains, which were isolated from cured fish in Hunan Province. Compared with the natural fermentation, inoculation with lactic acid bacteria (LAB) accelerated the degradation of myosin and actin in Zhayu, increased the trichloroacetic acid (TCA)-soluble peptide content by about 1.3-fold, reduced the colony counts of Enterobacteriaceae and Staphylococcus aureus by about 40%, and inhibited their lipid oxidation. In the texture profile analysis performed, higher levels of hardness and chewiness were observed in the inoculation groups. In this study, the bacterial community and volatile flavor compounds were detected through 16S high-throughput sequencing and headspace solid-phase microextraction-gas chromatography-mass spectrometry (HS-SPME-GC-MS). Inoculation with L. plantarum L1 reduced around 75% abundance of Klebsiella compared with the natural fermentation group, which was positively correlated with 2,3-Butanediol, resulting in a less pungent alcohol odor in Zhayu products. The abundances of 2-pentylfuran and 2-butyl-3-methylpyrazine were increased over threefold in the L1 group, which may give Zhayu its unique flavor and aroma.

Moisture Content and Mechanical Properties of Bio-Waste Pellets for Fuel and/or Water Remediation Applications

The current research is focused on the mutual comparison (mechanical properties, response to humidity) of agro-waste composite materials. The purpose of this work is directed at the valorization of agro-waste biomass products and to investigate their mechanical stability for transport or other applications (in dry and wet states). Three different types of agro-waste (oat hull (Oh), torrefied wheat straw (S), and spent coffee grounds (SCG)) were blended with kaolinite (K) and chitosan (CHT) at variable weight ratios to yield ternary composites. Mechanical properties were represented by measuring hardness (in compression mode) and elastic modulus (under tension mode). Young’s (elastic) modulus was measured both for dried and hydrated samples. The pelletized materials were prepared in two forms: crosslinked (CL) with epichlorohydrin and non-crosslinked (NCL). The hardness of the Oh pellets was poor (75 N) and decreased by four times with greater agro-waste content, while crosslinking affected the hardness only slightly. S pellets had the highest level of hardness at 40% agro-waste content (160 N), with a concomitant decrease to 120 N upon crosslinking. SCG pellets had the least change in hardness for both CL and NCL specimens (105–120 N). The trends of Young’s modulus were similar to hardness. Hydration caused the elastic modulus to decrease ca. 100-fold. In general, S and SCG composites exhibit the greatest hardness and Young’s modulus compared to Oh composites (CL or NCL) in their dry state.

Research and demonstration on reclaimation of chemical industrial wastewater with high salinity and hardness and purification of reverse osmosis concentrates

The demonstration is specifically designed to achieve the reclaimation of integrated chemical industry park wastewater (CIPWW) with high levels of hardness and salinity and the standardized discharge of concentrates generated during the reclaimation period by effectively composing dual-membrane technology combined by microfiltration (MF) and reverse-osmosis (RO) with multiple water treatment techniques. Concerning the concentrates generated by RO, the full-scale calcium-sulfate (CaSO4) crystallizer is creatively applied as the pretreatment unit for hardness removal with doubled catalytic ozonation-high performance biological aerated filter (O3-HBAF) and ultrafiltration (UF) as subsequent treatment technologies. Considering the characteristics of RO concentrates as high permanent hardness, high sulfate concentration and high refractory organic matter (ROM) content, pilot tests were conducted particularly focusing on the CaSO4 crystallizer and O3-HBAF unit which verified the reasonability of the technological process, and relevant operating parameters were optimized including flocculant dosage, catalyst dosage, etc. A series of adjustments were also made for the agent-addition devices of RO in order to stabilize the differential pressure facing variable influent circumstances. During over one-year of full-scale operation, the treated CIPWW was innovatively supplied for chemical fiber factories which established rigorous limitations on the impurity content of reuse water, and the water quality of purified RO concentrates partially met the requirements of class IV of Environmental Quality Standard for Surface Water (GB3838–2002, China). The application of CaSO4 crystallizer approximately saved the operation cost by 57.04 % compared with that of Na2CO3 softening process, and sufficiently recycled calcium ions from RO concentrates as CaSO4·2H2O products.

Machinability characterization in end milling of Invar 36 fabricated by wire arc additive manufacturing

Aircraft manufacturing sector manufactures a huge number of preforms near to the final profile or accuracy molds to avoid waste and to be more sustainable in terms of environment. However, this near net shape (NNS) profiles need requirements to avoid expansions and contractions in the manufacturing process, restricted tolerances and high dimensional stability. Therefore, the aim of this paper is to propose a machinability characterization finished milling study of Invar 36 samples fabricated by Wire Arc Additive Manufacturing (WAAM) technology using Minimum Quantity Lubrication (MQL). The results state that the WAAM sample roughness values reach the smallest values for all the cutting conditions although the average WAAM sample force increment is 9% comparing the wrought one owing to the high hardness level of WAAM samples (20%). Moreover, not only the statistical analysis demonstrates that the cutting speed is irrelevant in this machinability investigation, but it also optimizes the best roughness value (0.8 mm) when milling at the cutting speed of 50 m/min and feed per tooth of 0.06 mm/z. Finally, the main wear mechanism when finished milling WAAM sample of Invar 36 is adhesion on the rake a clearance faces.

Development of the chemical composition and modes of heat treatment of steel for railway wheels with increased wear resistance at high axle loads

One of the directions of the development of railway transport is increasing the load on the axle, while it is necessary to create new, more wear-resistant materials to increase the durability of railway wheels. At the same time, in many cases, a high level of hardness and strength must be combined with no less high values of plasticity and viscosity indicators. Purpose: to investigate the effect of the developed chemical composition and processing modes on the mechanical properties of laboratory-produced steels for railway wheels with increased wear resistance, which work in light braking conditions with high axleloads. Material and methodology. Research was carried out on steels of the experimental composition of the laboratory manufacturing method. Metallographic studies of experimental and industrial steels were performed on a light microscope "Neophot 32" and "Axiovert 200 M MAT" of the company "Carl Zeiss". Grinds were made mechanically. The microstructure was revealed by etching in a 2—3 % alcoholic solution of nitric acid (HNO3). Mechanical tensile tests at room temperature were carried out according to standard methods. Results. Based on the results of analytical studies and calculation models that allow predicting the mechanical properties of steels depending on the content of chemical elements in the steel, the chemical composition of small-volume experimental ingots for smelting in laboratory conditions was developed. Smelting of experimental melts has been completed. The possibility of obtaining a full set of mechanical properties and microstructure, standardized by the requirements of AAR M-107/M-208 for railway wheels of class D from developed steel, has been established.

Assessment of the drinking water quality from natural sources in the Kharkiv city

Improving the reliability and quality of the population's drinking water supply is one of the primary social problems, since the health of the population largely depends on the level of safety of drinking water. Purpose. To determine the composition of spring drinking water consumed by residents of different districts of the city of Kharkiv and to compare the assessment of the quality of drinking water from different natural sources. Methods. Field, laboratory-analytical, statistical. Results. Water samples from 5 natural springs in the city of Kharkiv, from which the population collects water for drinking purposes, were studied. It was determined that according to the organoleptic indicators, no excesses of the normative values are observed, the pH almost does not change seasonally, with the exception of the sample from the "Nemyshlianske" source. The analysis of total alkalinity in the autumn period showed that the standard was exceeded only in samples of the source of the Yunist park and along the street. Klochkivska, and in the spring period - only in the sample of the source on the street. Klochkivska. The total hardness in the samples ranges from 4.9 to 8.04 mmol/dm3 in the autumn period, and from 6.6 to 10.4 mmol/dm3 in the spring period. Excesses in chloride content are not observed in any of the investigated water samples. The iron content exceeds the MPC level only in water samples from the Nemyshlianske spring. The content of aluminum, zinc, cadmium, copper, lead, ammonia and nitrites in the samples is significantly below the MPC level, and almost does not change by season. Conclusions. The formation of the general quality class of water samples from natural sources is significantly influenced by the high level of total alkalinity, total hardness, and iron content in some sources of non-centralized water supply. According to the integral ecological index of water samples in the autumn period from natural sources "Nemyshlyanske", Park "Yunist" and along the street. Klochkivska belongs to the II quality class, i.e. pure water. The integrated ecological index for all other water samples in the autumn period assigns these sources to the I class of water quality - very clean. The calculation of the integral ecological index for water samples from all natural sources in the spring period refers them to the II quality class.

Fabrication and Characterization of Oxygen-Carbon-Contained CrMnFeCoNi Coatings Electrodeposited in DMF-CH3CN Solution with and without Supporting Electrolyte LiClO4

Oxygen-carbon-contained CrMnFeCoNi coatings were electrodeposited in an organic solvent of DMF-CH3CN (N,N-dimethylformamide-acetonitrile) containing chlorides of chromium, manganese, iron, cobalt, and nickel, with or without supporting electrolyte lithium perchlorate (LiClO4). The coatings’ composition, structure, hardness, and electrocatalytic properties were examined. The presence of lithium in coatings obtained with LiClO4 showed it unsuitable as a supporting electrolyte in this fabrication process. Without LiClO4, oxygen-carbon-contained CrMnFeCoNi coatings were obtained at constant potentials at −2.0, −2.5, and −3.0 V (vs. SSE) by enhancing the concentrations of the target metal ions in the solution. These coatings were mainly amorphous with nanocrystals, which were comprised of &gt;50 atom% oxygen atoms, &gt;7 atom% carbon atoms, and near equiatomic Cr, Mn, Fe, Co, and Ni, showing a high level of hardness and advanced electrocatalytic activity in the oxygen evolution reaction.

Experimental investigation on surface morphology and recasting layer of Si3N4-TiN composites machined by die-sinking and rotary EDM

Si3N4-TiN composites have extensive manufacturing applications because of their first-rate mechanical and thermal properties. Conversely, they are very demanding on machines that use conventional practices because of their superior strength and hardness. Electrical discharge machining is a viable substitute for machining of Si3N4-TiN composites through electrical erosion. However, very few studies have been conducted on the machinability and surface characteristics of electrical-discharge-machined composites. This study focuses on the materials processing characteristics of a Si3N4-TiNcomposite using rotary EDM and die-sinking EDM performed with a Cu electrode. In addition, the surface and cross section of the subsurface of the composite were examined, along with energy dispersive X-ray analysis, to identify the elements present on the machined surface. It was found that the high level of hardness and low level of toughness of the Si3N4-TiN composite contributed to the presence of microcracks, globules, pores, recast layers, and craters on the EDMed surface. The recast layer thicknesses of the die-sinking EDM (optimum hole, 106 μm; best hole, 151 μm; worst hole, 166 μm) and rotary EDM (optimum hole, 53 μm; best hole, 55 μm; and worst hole, 58 μm) were examined. In addition, the presence of pores and ablation increased significantly during the rotary EDM process. Rotary EDM parameters capable of producing a minimum white layer thickness were also investigated. Finally, the porosity levels were estimated according to the number of pores using ImageJ software. For the die-sinking EDM, the estimated porosity values for the optimum, best, and worst holes were 14.989%, 19.525%, and 21.706% respectively and for the rotary EDM, these values were 24.873%, 33.04%, and 37.99% respectively.

Additive Manufacturing of Tool Steels

The public funded project “AddSteel” aims to develop functionally adapted steel materials for additive manufacturing (AM). Based on the AM process laser powder bed fusion (LPBF), the holistic process chain, including alloy design, powder atomization, AM, and postheat treatment, is considered to achieve this objective. Tool steels are usually characterized by higher carbon content and limited weldability, leading to limited processability for LPBF. To extend these limitations, different approaches for tool steels are investigated: for high‐carbon tool steels, the effects of lower martensite start temperature are investigated using the alloy 1.2842 as an example. A low martensite start temperature seems to be advantageous for crack‐free processing with LPBF. In order to avoid a high hardness level after rapid cooling, the use of a hot work steel with a carbon content of 0.2 wt% is investigated. Due to the chemical composition of the material, a moderate preheating temperature &lt;300 °C is required. In addition, very high scanning speeds are possible with an improved shielding gas flow. Finally, the experience along the process chain with the standard steels is used for a modification of the alloy 1.2344. The effects of this modification on AM and heat treatment are investigated.