Influence of Impurity Morphology on the Fatigue Strength of High-Purity Structural Steel Melted in an Electric Furnace

An experimental study was carried out on the effect of oxidation temperature and the oxide film composition on the compressibility of porous materials. Samples were annealed at different temperatures; the size change in the samples after annealing was measured. The phase composition of the oxide layer was investigated. Magnetite was generated at between 350 and 450°C, and two-phase oxide was formed at 550°C, after oxidation, weight gain was determined. The presence of pore overgrowth, which reduces porosity, was confirmed by metallographic tests. The maximum porosity is found in the oxidized samples produced by pressing at room temperature. The process of high-temperature oxidation of iron powder before pressing and in the state of free filling in a fluidized bed, as well as the effect of the content of oxides on magnetic characteristics, has been studied. The impact of oxidation on the compressibility of samples of iron powder was investigated. In this study, it was observed that the range of 350-450°C, offers the best compressibility and the necessary composition of the oxide film, which is also related to the presence of magnetite in the iron oxide coating. It is the ideal temperature for oxidation and repressing. The deformation of porous materials exposed to iron powder oxidation was tested.

Experimental Study on the Effect of Oxidation on the Compressibility of Iron Powder

Saraireh¹

2023

The Effect of Strain Rate on the Friction Coefficient

Svoboda,

Jopek

2024

The Male and Cockroft ring compression test is one of the methods used to determine the coefficient of friction in forming. This method can be used to determine the coefficient of friction without the need to measure the force. This paper describes the results of the Male and Cockroft ring compression test for the Hardox 450 material at different strain rates without lubricant. The experiment was performed on ZD40 hydraulic press and CFA-80 pneumatic die hammer at the Faculty of Mechanical Engineering of Brno University of Technology. The test results were recorded in a calibration diagram. The results show that the strain rate has a significant effect on the coefficient of friction, specifically such that as the strain rate increases, the coefficient of friction decreases.

Experimental Investigation of Thermofriction's Impact on Surface Hardness of Steel Products'

Al-Saraireh

2024

The impact of thermofriction on surface hardness has been investigated in this study, the surface of treated products is one indication of quality indicators. It has been noted that the thermal conductivity of the workpiece and tool material affects the irregular dispersion of heat in the processing zone. For evaluating the average integral rates of heating and cooling of the layer, the metal dependences have a significant impact on the form and properties of the friction-strengthened layer. It was found that when the feed rate increases, the hardened layer's depth decreases. The harder layer's depth increases as disk rotation speed (rpm) increases. when the disk rotation speed is increased to 265 rpm and the hardening depth (h) is 0.2 mm or less, it is said to be at N = (190-250) rpm. After heating the treated surface areas to a temperature between 130°C and 160°C above the critical temperature, the treated surface areas were then cooled applying compressed air to achieve the ideal surface hardness. After the hardening process, the surface hardness of blanks made of steel 1045 reached HRC 65, which is higher than conventional hardening.