Tool steels AISI O1 are widely used in the manufacturing industry to produce a wide variety of tools, moulds, and other applications requiring high wear resistance. Wear resistance is identic with high hardness, and the combination can be obtained by hardening-tempering and cryogenic treatment. However, cryogenic treatment requires liquid nitrogen, which is relatively expensive. Therefore, this study aims to determine whether to cool to produce high hardness, which is close to the hardness value of 69 HRC due to cryogenic treatment. The hardening process was carried out by heating the steel at a temperature of 880 °C and holding it for 30 minutes, then quenching using air, oil SAE 10, water with 15% salt, and ice water. The microstructure of the test sample was observed with an optical microscope, and the hardness was tested with a Rockwell hardness tester. The test results showed that the microstructure changed from pearlite and ferrite to bainite and martensite after hardening-quenching. The lower the quenching media temperature, the higher the hardness. Ice water quenching resulted in a fully martensitic structure, and the highest hardness was 66.37 HRC. Ice water is a quenching medium that can produce hardness almost close to the hardness of cryogenic treatment.

Welding is a prevalent joining technique used on metals in industrial manufacturing. It is very important to detect welding defects that may occur without damaging the welding constructions. The conventional ultrasonic inspection is the most widely used non-destructive test method for the detection of weld defects. Phased Array Ultrasonic Testing (PAUT) is a significant method within the category of ultrasonic non-destructive testing methods because ultrasonic phased arrays offer significant technical advantages over conventional ultrasonic methods such as improved sensitivity, accurate characterization and faster inspection. The aim of this article is to provide a comprehensive review on analysing defects in welded joints by utilizing PAUT. Different studies in the literature related to the non-destructive testing of weld joints by PAUT have been reviewed. Various examples of how the type, depth, and size of welding defects are detected in a highly effective manner have been provided. As a result, it was concluded that phased array ultrasonic testing is a highly efficient technique compared to conventional ultrasonic methods for detecting welding defects.

This study observed the ballistic performance of the composite armor reinforced by an alumina ball with various matrix materials. The investigation was conducted numerically to establish an effective design of the composite armor for protection against a 7.62 mm bullet impacting at 800 m/s speed. Al 5083, Ti-6Al-4V, Weldox 700E, and Q235 steel, along with ceramic balls acting as reinforcement, make up the composite. The simulation was set in a 3D model and performed using Abaqus finite element software. The outputs of the simulation present the residual velocity, the depth of penetration, the optimized weight-to-penetration depth ratio, and the deformation pattern. The results indicated that the composite armor with ceramic ball reinforcement produced the optimum design using a matrix of Ti-6Al-4V. The matrix with a higher Young modulus has a higher velocity decrease. The matrix with a higher plastic equivalent strength has a higher resistance to the projectile deformation, marked by mushrooming during its penetration. On the contrary, the matrix with a lower plastic equivalent strength forms a ductile hole. This work guides to determination of the optimal design of composite armor containing ceramic balls as reinforcement, considering the different matrix materials.

Metal is an essential substance in the industrial world for supporting human life and technological advancement. Shaping and increasing metal’s ability involves the heat treatment process. This research aims to see how the microstructure and hardness of metal change after being heat treated with quenching and tempering medium at room temperature and ice. The experiment was conducted utilizing a heat treatment process involving heating the material to 840°C for 60 minutes, then quenching it with water and ice and tempering it at 200°C for 20 minutes. The hardness test employs the Rockwell Hardness Test method, which uses a 9-point hardness scale with the primary load (P) of 150kg-f. The observations for the micro test were in the form of density variations in ferrite, pearlite, and martensite crystal grains. Microstructure investigations showed the presence of martensite in the material after being heat-treated. The hardness test showed that the carbon steel material experienced a decrease in hardness from the initial value of 43.12 HRC to 39.32 HRC and 38.14 HRC after quenching water and ice water. The comparison of tempering has no significant effect on hardness with values of 40.63 HRC and 38.94 HRC tempering followed by water-quenching and ice water-quenching, respectively.

This study examines the density, porosity, microstructure, and hardness of aluminum raw materials from used pistons using gravity dies casting and gravity investment casting processes. Gravity die casting and gravity investment casting at a casting temperature of 750°C were employed in this research. Emission Spectrometry is used to determine the chemical composition of a substance (ASTM E-1251). Porosity was measured using macro photography and a digital microscope, with the findings of each mold temperature fluctuation compared. The Rockwell hardness tester is used to determine the hardness of a material (ASTM E-384). A metallographic microscope was used to examine the microstructure of the castings (ASTM E3-11). According to ASTM B-85 standards, this material comprises 71.05% (Al) composition, 13.65% (Si), 7.178% (Cu), 3.4508% (Fe), 1.7870% (Zn), and additional components up to 100%, and is categorized as Aluminum Al-Si (Aluminum-Silicon)A413.0. The density of the test object was calculated using gravity die casting at 2.6972 gr/cm³ and gravity investment casting at 2.6764 gr/cm³. The quantity of porosity impacts the density value, according to the results of porosity observations. The phase (Al) and the phase (Zr) are observed in the microstructure results (Si). In gravity investment casting, the beta phase granules (Si) appear to be larger and fewer. The beta phase granules seem smaller and more abundant in gravity die casting. The hardness value is influenced by the size, number, and dispersion of beta granules. Hardness testing with gravity investment casting yielded a hardness value of 86.84 HVN, according to the results.

Welding techniques have historically been commonly employed in machine construction for repairs, hardening tool coatings, thickening worn sections, and connecti