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Nowadays engine capacities of vehicles spread in a wide range due to different vehicle power demands. Power density of engines affects exhaust gas and therefore exhaust gas temperature varies from 650 °C to 1000 °C in exhaust manifolds. Depending on the exhaust gas temperature, different types of iron based alloys are used as manifold materials such as ferritic ductile cast irons (GGG40, SiMo), austenitic ductile cast irons (Ni-resist D5S), ferritic cast stainless steels (ACIHK30, AISI 409) and austenitic cast stainless steels (CF8C). In this study high temperature oxidation behavior of different cast alloys used as exhaust manifold materials like, (i) GGG40 ferritic ductile cast iron, (ii) SiMo ferritic ductile cast iron (iii) AISI 409 ferritic cast stainless steel and (iv) CF8C austenitic cast stainless steel, were investigated.

Steel slag, a by-product of the steelmaking process, may turn into a useful material with many different applications if it is properly characterized. In the present study, samples of electric arc furnace slag received from a local steel producer have been analyzed in an attempt to solve the problem of waste disposal. The slag microstructure has been evaluated by light and electron microscopes and elemental compositions of the phases are determined by microanalysis. The quantities and hardness values of the phases present in the microstructure are measured by image analysis and micro-hardness tester, respectively. Particle size distribution, particle shape and bulk chemical composition are also determined and compared with an abrasive grit material used in shipyards for paint removal. Results show that present slag has a high potential to be used as blasting abrasive in place of the expensive grit material.

In this study, Al-0.80Mg-0.85Si alloy was modified with the addition of 0.3 wt.-% zirconium and the variation of microstructural features and mechanical properties were investigated. In order to produce the billets, vertical direct chill casting method was used and billets were homogenized at 580 °C for 6 h. Homogenized billets were subjected to aging practice following three stages: (i) solution annealing at 550 °C for 3 h, (ii) quenching in water, (iii) aging at 180 °C between 0 and 20 h. The hardness measurements were performed for the alloys following the aging process. It was observed that peak hardness value of Al-0.80Mg-0.85Si alloy increased with the addition of zirconium. This finding was very useful to obtain aging parameters for the extruded hollow profiles which are commonly used in automotive industry. Standard tensile tests were applied to aged profiles at room temperature and the results showed that modified alloy had higher mechanical properties compared to the non-modified alloy.

High alloy steels are widely used for high temperature and corrosion resistance applications in power plants, e. g., in chemical and petroleum industries. Mechanical properties of these alloys (e. g., hardness and tensile strength) can be altered by suitable heat treatment. This paper deals with failure investigations of a cast valve made of high alloy steel. The samples were taken from valve body and prepared by metallographic techniques. Microstructural defects causing cracking were investigated using light microscopy and scanning electron microscopy/energy dispersive X-ray spectrometry. Segregation areas at the grain boundaries in the microstructure of the material were observed. Casting was repeated by taking necessary measures during the production in order to eliminate these heterogeneous regions and then suitable heat treatment was applied to the part. The samples taken from the last part were also examined. As a result, a homogeneous microstructure was obtained and no macro or micro cracks were observed.