جستجوی مقالات مرتبط با کلیدواژه "surface hardening" در نشریات گروه "مواد و متالورژی"

Surface alloying by TIG process, is one of the techniques to improve the surface properties of the steels. This method can be conducted without changing the substrate properties. Alloying is carried out by adding certain alloying elements before or during surface melting. In this study, Surface alloying is done using nickel and Tungsten Carbide reinforcement particles, and by gas Tungsten arc welding process on steel St52. Surface melting was conducted with applied current of 130 mA and the effect of increasing the percentage of WC powder on surface hardening of the samples were evaluated. The range of increasing hardness the coatings made between 225 to 680 Vickers was measured and the amount hardness of the uncoated sample is about 180 Vickers. Infrastructure assessment of worn surfaces was performed by scanning electron microscopy SEM. Typical abrasion resistance was evaluated by means of reciprocating wear machine. The results of wear surfaces showed that by increasing the amount of WC reinforcement particles, the matrix strength against changing the form is increased, and eventually causes to improve the wear resistance of the samples. The wear test results showed that with increasing percentages of Tungsten Carbide reinforcement particles up to 80%, the amount of weight loss were significantly reduced, and the wear rate of the samples decreases up to 100 ⁄ .

This paper considers the effects of plasma nitriding parameters including screen hole size, top lid type (screen or iron plate), temperature and composition of the treatment gas, on the surface properties of DIN 1.6580 low-alloy steel. Nitriding was carried out at 520, 550 and 580°C for 5 hr in the gas mixture of (N2/H2); 3:1 and 1:3. The properties of nitrided specimens were assessed using metallographic techniques, XRD, Micro-hardness measurements, and SEM. X-ray diffraction analysis confirmed the formation of and during the nitriding process. The findings show that the thickness of the compound layer increases with the increase in the treatment temperature and nitrogen percentage in the gas mixture moreover increase in the screen hole size has no effect on the compound layer thickness in the screen top lid condition but that an increase in the screen hole size at the same temperature results in an increase in the thickness of the compound layer in the iron plate top lid condition. The results of micro-hardness measurements indicate that surface hardness increases with the increase in the temperature and nitrogen volume in the treatment gas. It was also found that hardness values obtained using screen top lid are relatively greater than those obtained using iron plate top lid.