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The paper presents the results of cold upsetting testing of 16.5 mm-diameter 20MnB4 steel wire rod. The main purpose of the study was to evaluate the ability of wire rod produced in industrial conditions for further cold metal forming. Due to the fact that cracks occurred in the test material at different strain values, the authors made an attempt to answer the question whether there are any crack initiators in the material structure, or the observed cracks are due to the manufacturing process parameters. In order to determine the causes of cracks appearing during upsetting tests, micro- and macroscopic observation techniques were used. For the macroscopic examination, an Olympus SZ-31 microscope was used, while a Nikon Ma-200 microscope was employed for the microscopic examination. The microscopic examination was carried out both in a light and dark fields. To evaluate the effect of surface topography on the crack formation tendency, the results of macroscopic observation under a magnification from 6.7x to 45x were used.

It is found from results of studying rolled steel from special alloyed steels of industrial grades 30G1R, 40Kh and laboratory grades 12KhN, 38KhGNM, 41Kh1 that a change in the ratio of Mn:S concentration in the range of 21–620, P content from 0.004 to 0.022 wt.%, non-metallic inclusions up to point 2.5 according to GOST 1778, N up to 0.010%, H up to 0.0005%, with total pressure created by gas-forming elements up to 1.05 atm, are not critical for occurrence of defects and rolling capacity for cold upsetting. Determination of the characteristics of NI, and CANI content in steel 40Kh round rolled product shows that metal corrosion resistance increases by more than a factor of three with a reduction in CANI2 content and inclusions of the system CaO–Al2O3–MgO containing up to 5 wt.% SiO2, and the insignificant effect of other types of inclusions. A study of the metal of high-strength fasteners manufactured by JH (Taiwan), OF, AL (USA) shows that it has a significantly lower content of other types (corundum, calcium, aluminate, sulphide) of inclusions, and conversely better corrosion resistance.

The thermal chemical vapor deposition (CVD) process was utilized to fabricate 6H-structured SiC coating dies with carbon control. The carbon-rich clusters along the SiC grain boundaries acted as a pinning site to suppress irregular crystal growth and to homogenize the fine-grained structure. These massive carbon-supersaturated (MCSed) SiC dies with a thickness of 4 mm were utilized for upsetting pure titanium bars in dry and cold conditions. Under a stress gradient from the contact interface to the depth of the SiC coating, the carbon solute isolated from these carbon clusters diffused through the grain boundaries and formed free carbon agglomerates on the contact interface to the pure titanium bars. These in situ-formed free carbon agglomerates acted as a solid lubricant to sustain the friction coefficient at 0.09 at the hot spots on the contact interface and to protect the dies and bars from severe adhesive wearing.

The forming behavior of AA6061 boron carbide composites produced by stir casting process was investigated with the cold upsetting test. The composites containing 0%, 5%, 10% and 15% of B4Cp reinforcements were investigated with the cold upsetting test in Universal Testing Machine under tri-axial stress state condition. SEM images were taken to identify the presence of B4Cp particle in aluminium matrix. From the analysis, it was found that the hardness of composite was increased due to increasing amount of boron carbide particle in the composite and the density was decreased due to the lower value of density of boron carbide. The maximum true axial stress, true hoop stress and hydrostatic stress were gradually increased in the event of increasing order of B4Cp in the composites. Finally, it was found that in the stress – strain curve, the boron carbide was the main factor in improving the compressive strength of composites because of its high hardness.

Since most hot and cold metal-forming processes originate from various casting processes, it is important to test their susceptibility to the deformation of new materials. Cast rods of CuMg alloys with a Mg content of 2, 2.4, 2.8, 3, 3.2, 3.6, and 4 wt.% were obtained in the continuous casting process with pure copper as a reference material in order to obtain information on the material’s ability to withstand 50% deformation. The materials in the as-cast state were subjected to solutioning, cold drawing, and recrystallization. After each process, samples were taken and subjected to upsetting tests with 50% deformation applied in a single operation. Additionally, materials in the as-cast state were subjected to upsetting tests at 700 °C. The hardness and electrical conductivity of each sample were analyzed. Selected samples were subjected to microstructural analysis. The obtained results show an increase in hardness from 46 HB to 90–126 HB, and a further increase to 150–190 HB with a quasi-linear decrease of electrical conductivity, which proved the influence of solid-solution and strain hardening, respectively. The microstructural analysis proved that such deformation does not cause microcracks. Furthermore, in the case of CuMg up to 3 wt.% of Mg, the alloying additive completely dissolved after solutioning.

The development of microelectronics results in higher demand for copper microwires and thin foils. Higher demand requires conducting research to obtain knowledge on the influence of extreme plastic deformation on materials’ susceptibility to plastic processing without the loss of coherence. One of the key factors contributing to rupture during the plastic deformation of copper is the presence of micrometer-sized, eutectic Cu2O oxides, which are weakly bound to the copper matrix. These oxides are formed during the metallurgical stage of wire rod copper manufacturing. Copper wire rod of the ETP (electrolytic tough pitch) grade was subjected to wire drawing followed by cold-rolling. Applying different states of stress during plastic deformation (wire drawing, cold-rolling, and upsetting) made it possible to specify the conditions required for Cu2O oxides’ fragmentation due to the extreme total deformation. Qualitative and quantitative analyses of the Cu2O oxides’ evolution and fragmentation as the plastic deformation progressed were the main focus of this paper. It was determined that major fragmentation occurred during the initial stages of plastic deformation. Applying further extreme deformation or changing the state of stress during plastic deformation did not facilitate the continuation of fragmentation. It was only their shape that was becoming elongated.

Aluminum metal matrix hybrid composites were synthesized through powder metallurgy route from ball milled powders to yield the compositions: Al + 0% TiO 2 , Al + 2.5% TiO 2 , Al + 2.5% TiO 2 + 2% Gr, and Al + 2.5% TiO 2 + 4% Gr. The densification and deformation properties of sintered Al–TiO 2 –Gr composites during cold upsetting were investigated experimentally. The powder preforms are compacted using suitable punch and die in 40 kN hydraulic press and the initial percentage theoretical density was maintained as 85%. Sintering was done in an electric muffle furnace at the temperature of 590 °C for a period of 3 h. The sintered preforms were subjected to incremental compressive loading of 10 kN until cracks were found at the free surface. The true axial stress (σ z ), true hoop stress (σ θ ), true hydrostatic stress (σ m ), and true effective stress (σ eff ) were calculated for all the preforms and all these stresses are correlated with the true axial strain (ε z ). The densification behaviors of the composites were studied against true axial strain (ε z ) and lateral strain. Better densification and deformation property were obtained for pure aluminum preforms compared with other composite preforms. Addition of TiO 2 to the pure Al and Gr reinforcements increases the strength coefficient of the Al–TiO 2 composite.

The innovative combination of equal channel angular pressing (ECAP) and cold upsetting (CU) is significant for producing high-strength Al alloy fasteners with ultrafine grains. However, the relationship between microstructure evolution and mechanical strength during composite deformation remains unclear. In this study, using transmission electron microscopy, electron backscatter diffraction, and mechanical property tests, it is found that the mechanical strength increases with each step of composite forming operations due to the accumulation of dislocations. Forest dislocations also contribute to the generation of ultrafine grains within deformed grains, particularly in ECAP-CU processed grains. Moreover, we observe the formation of lamellar structures within the shear bands in the head of the ultrafine grain fastener after final composite deformation, which is full of dense dislocation walls and dislocation cells. The rearrangement of these fine grains and lamellar structures yield a strong (011) (brass) texture during composite deformation under the effect of shear force and accumulation of plastic strain. This study provides a theoretical reference for the manufacture of high-strength aluminum alloy fasteners through composite deformation and helps improve processing technology.

The forging industry has increasingly emphasised quality and reproducibility, making computer simulations essential for predicting and improving the process. A major challenge in cold upset forging is billet buckling, which leads to defective products. Existing numerical models, such as the Euler and Rankine-Gordon formulas, mainly focus on elastic buckling. This study aimed to develop a numerical model that defined inelastic buckling during forging, particularly in cold upset forging, which could be used to determine the buckled billets and their stresses, identify the deflection point for different billet geometries, and specify the optimum billet geometry for aluminium. A numerical approach was used to model the forging operation and obtain simulation data for stress variation against die strokes. Seven billet geometries (10–40 mm in diameter, each with a length of 120 mm) and three frictional conditions (µ = 0.12, 0.16, and 0.35) were applied. The simulation results showed that the billet geometry and the strain hardening exponent had a crucial impact on the buckling behaviour, while friction seemed to alter the overall billet stresses. Rigorous non-linear regression and iterations showed that the numerical model successfully estimated the buckling stresses but failed to identify the buckling points through stress differences.

Aluminium finds wide application in mechanical engineering due to its low density and corrosion resistance. In this research, aluminium was subjected to two different metal forming technologies—cold forging (upsetting) and equal channel angular pressing (ECAP)—to obtain improvement in its exploitation properties. Parallel to changing mechanical properties by using these two processes, there was a change in the microstructure of the material. The resulting microstructures were examined using an optical microscope. A different treated aluminium was subjected to erosion wear in various time intervals. Wear testing was conducted for two different impingement angles causing abrasive wear and impact wear. The erosion mechanisms were examined by scanning electron microscopy. These results showed that there is no statistically significant difference in erosion wear for different states at the same impingement angle. However, the difference is noticeable at different wear angles. The significance of the difference in wear of the samples treated with the forging and ECAP techniques was validated by statistical analysis with tests of different sensitivities. The results of the t-test showed that ECAPed samples present a statistically significant difference in the loss of mass due to variations in erosion angle during the 30, 45, and 60 min wearing. A substantial difference in the change in sample mass is also visible for the forged state worn for 60 min.