Papers by Keyword: Hardening

Abstract: The efficient development of high-quality sheet metal components increasingly depends on predictive numerical simulations conducted prior to forming operations. Achieving such accuracy requires precise calibration of models that represent the complex mechanical behaviour of metals. Mechanical testing provides the essential data for calibration, revealing material anisotropy, strain hardening, and ductile fracture. However, traditional characterisation approaches are often labor-intensive, time-consuming, and prone to operator variability. Within the phenomenological framework, numerous tests are typically required to capture the full material response, including repeats for statistical reliability, leading to high costs and extended lead times. To address these limitations, this study introduces an automated mechanical testing platform designed to rapidly acquire experimental data useful for material models. The use of a cobot enables fully automated test sequences, ensuring high repeatability and reducing manual intervention. When combined with automated model calibration, this approach provides a direct link between the physical material (metallic sheet) and its virtual mechanical representation.

Abstract: In this work, the effect of the maximum particle size and the molar concentration of the alkaline hardening solution on the mechanical response in uniaxial compression of geopolymeric mortars manufactured from the geopolymerization of Peruvian mine tailings dust was evaluated. The mechanical results found showed that the average mechanical resistance increased as the molar concentration of the hardening solution increased from 10 to 15M, on the other hand, it was possible to verify that as the particle size of sand and mine tailings is greater, the mechanical resistance values increased. The mechanical data found are in good agreement with the porosity results, that is, as the porosity values increased, the mechanical resistance gradually decreased. The stiffness values reported in the studied geopolymeric mortars showed a slight increase when the values of molar concentration and maximum particle size increased. All the mortars studied presented a similar microstructure, with fine sand particles dispersed within a continuous phase of geopolymer (geopolymerized mining tailings).

Abstract: ASSAB 705 steel is a machinery steel that used in several industries due to its mechanical properties, for components manufacturing. Hardening process is applied to ASSAB 705 to increase mechanical strength thereby increasing hardness. Conversely, an increase in the hardness value will decrease toughness value so that components are easily damaged due to heavy workloads. The optimal combination of hardness and toughness enhances abrasion resistance and maintains component strength against working loads. It is necessary to investigate parameters of hardening process and its effect on the hardness and toughness of ASSAB 705 steel. This study used Design of Experiment with Taguchi method and ANOVA statistical analysis. Hardening parameter with austenite temperature factor, quench media, and tempering temperature, is used to optimize the combination of hardness-toughness value of ASSAB 705 steel. Results of this research show that tempering temperature is the most influential factor on hardness and toughness values. Optimal combination of mechanical strength is obtained at a hardness value of 50.78 HRC (increase of 44.85%) and a toughness value of 1.15 J/mm² (increase of 109.09%). These values ​​were obtained from the hardening method: austenite temperature of 825°C, oil quench medium, and tempering temperature of 180°C. The desirability value for combination of hardening process parameters is 0,682802.

Abstract: Induction hardening is carried out to increase the hardness of the axle shaft surface. Axle shaft specimens were hardened from the bearing seat area to the spline area of the axle. The hardness requirements of the scope of the shaft met 400-450 HV of the JIS G 0559 standard. The axle shaft's hardening process with induction coil stops in the field before reaching the spline area. It causes the hardness becomes uneven and not comply with the standard. The re-hardening process is often carried out to repair rejected parts. In this work, the result of the re-hardening process is analyzed and compared with the first hardening process—the analysis focus on mechanical properties such as static test (torque test), fatigue testing, and hardness. Microstructures were used to verify the result of the process. The results showed that the results of re-hardening can meet the expected qualifications. The difference in breaking torque (static test) values ​​is 4,428.155 Nm for hardening specimens and 4,287.832 Nm for re-hardening with a standard torque of 4,000.000 Nm, all samples fractured in the spline area. High fatigue values ​​were obtained from the hardening results, with 216,265 cycles and 252,224 cycles for re-hardening. The results of the re-hardening hardness test obtained from Vickers are higher than the hardening results. The results of microstructural testing in both hardening processes contained ferrite and Fe3C on the surface and for the core consisting of ferrite and pearlite. Based on the analysis, the re-hardening process has no significant effect compared with the hardening results. Therefore, in this case, the re-hardening process can be used to fix the failed part.

Abstract: Pure Niobium is a material of interest for high-energy-physics applications including superconducting accelerators. Cold-rolled sheets of Nb exhibit significant plastic anisotropy. Here we report on the mechanical and forming properties of 99.95% pure, 1.02 mm thin, cold-rolled sheet. Uniaxial tension, biaxial tension and disc compression experiments are performed, the first two at multiple angles to the rolling direction of the sheet. The material is very ductile (uniform elongation ~30%), and exhibits significant plastic anisotropy (e.g., the R-values range from 1.2 in 45^o to 2.5 in 90^o). The results are used to calibrate the Yld2000-2D anisotropic yield function, with an exponent of 6 as Nb is BCC. They are also used to extract the hardening curve beyond the limit load in uniaxial tension. Deep-drawing experiments are performed using a die of 27.6 mm dia. and a punch of 25.4 mm dia. Blanks of various diameters are used. The successfully drawn cups exhibit significant earing. The experiments are simulated using Abaqus/Standard and shell elements. It is shown that a properly calibrated material model enables the numerical simulations to match the experiments.

Abstract: The development of the technology for laser hardening of the axle seats of rail vehicles aims to improve the high-cycle service life of these axles under wheel pressing and thus to increase safety in rail transport. Laser hardening can create high compressive stresses that increase the fatigue resistance of the material. The paper will present the results of this development on the EA1N material together with the documentation of the microstructure, hardness profiles and correlations with the internal residual stresses as well. These compressive stresses can play a crucial role in significantly increasing the fatigue resistance of the axles under operation.

Abstract: The article discusses a powdered material - carbidostal. Comparative characteristics of carbidostals, tool steels are given and hard alloys. Methods of producing and producing carbidostals are considered. Conditions for free separation of residues of impregnating material from the surface of the article are established. The reasons of volumetric change of amount of carbides and binding by height of impregnated press are studied.

Abstract: In this paper presents theoretical and experimental studies of the process of forming the cellular components. The influence on the geometric parameters of cells of different stamping mode is determined by the required number of time steps, it shows the effect of hardening.

Abstract: One of the ways to develop existing methods of hardening is creation of hybrid technologies that combine the principles of chemical heat treatment and surface plastic deformation. This paper proposes a nitriding technology followed by ultrasonic treatment. As a result of such sequence, a surface layer is formed that has an increased hardness and depth of hardening, in comparison with combined methods used separately.

Abstract: The metal workpiece Surface Layer (SL) Residual Stresses (RS) modeling and computational algorithms creation relevance is shown. The RS forming discrete elastoplastic finite element model at Surface Plastic Deformation (SPD) hardening treatment, including technological inheritance effect, is presented. A model feature is the complex non-monotonic types of metal loading and subsequent unloading and hardened body effect consideration, as well as residual stress tensor components evaluation as a result of these effects. Residual stress tensor components calculations in the workpiece hardened surface layer after treatment with different routines are performed. The metal hardening effect on the residual stresses values and distribution is established. The correlations between the residual stress tensor components and the main treatment routine parameters - the roller tension and profile radius are established.