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Öğe Clustering effect on high temperature tensile behaviour of vanadium microalloyed steel(Elsevier Science Sa, 2007) Gunduz, S.; Cochrane, R. C.in the present work, high temperature tensile behaviour of vanadium microalloyed steel has been examined under as-received, air cooled and stainless steel cylinder tube cooled conditions. The results indicated that ultimate tensile strength (UTS) of the as-received samples and samples cooled in air and in a stainless steel cylinder tube showed larger differences after testing at 450 degrees C where the air cooled samples displayed the highest UTS. The increased in UTS at 450 degrees C suggests there is interaction between dislocation and precipitate particles or solute atoms which make dislocation movement more difficult. This is due to the presence of solute atoms such as carbon and nitrogen in solid solution. Tempering steel samples at 450 degrees C after air cooling or accelerated air cooling indicated that increasing tempering time reduced clustering effect of V and C on UTS by the formation of VCN precipitates, as a result steel samples showed a decrease in UTS.Öğe Effect of Aging on the Microstructure and Mechanical Properties of Magnesium Alloy AZ31(Springer, 2016) Kerenciler, H.; Gunduz, S.; Erden, M. Akif; Turkmen, M.; Karabulut, H.The structure and mechanical properties of magnesium alloy AZ31 are studied after conventional and deformation aging under conditions corresponding to the thermal cycle of polymerization in paint coating of cars. The aging is conducted after 3-h solution treatment at 400A degrees C, water quenching, and aging at 180A degrees C for from 10 min to 6 h. Some of the specimens are deformed by 0.5% right after the solution treatment and then aged by the same regime.Öğe Effect of strain ageing on the mechanical properties of interstitial-free steels under as-received, heat-treated, and spot-welded conditions for automotive applications(Sage Publications Ltd, 2010) Bak, A.; Gunduz, S.In this study, the artificial ageing behaviour of interstitial-free steels is investigated under as-received, heat-treated, and spot-welded conditions. All the test specimens except those in the as-received condition were austenitized at 950 degrees C for 15 min followed by water cooling. Both as-received test pieces and heat-treated test pieces were prestrained by 8 per cent in tension, and then aged at 170 degrees C for 10 min, 20 min, 40 min, 60 min, 80 min, and 120 min. The experimental work revealed that strain ageing takes place in as-received, heat-treated, and spot-welded test pieces. However, strain ageing is more pronounced in heat-treated test pieces and spot-welded heat-treated test pieces, compared with the as-received test pieces and spot-welded as-received test pieces. This is due to the nature of heat treatment and spot welding.Öğe The Effect of Vanadium and Titanium on Mechanical Properties of Microalloyed PM Steel(Springer, 2016) Gunduz, S.; Erden, M. A.; Karabulut, H.; Turkmen, M.The effect of Ti and V additives on the microstructure and mechanical properties of microalloyed powder metallurgy (PM) steels is investigated. The microstructure of microalloyed PM steels is characterised with the help of optic microscope, SEM and EDS. The results showed that the addition of Ti and V elements has a beneficial effect on the improved mechanical properties. Ti-V microalloyed PM steels can be used to take advantage of improved grain refining propensity of titanium, whilst allowing vanadium to be used as dispersion strengtheners and to enhance the hardenability and transformation characteristics.Öğe The Effects of Heat Treatment on the Microstructure and Mechanical Properties of Nb-V Microalloyed Powder Metallurgy Steels(Polish Acad Sciences Inst Physics, 2019) Turkmen, M.; Erden, M. A.; Karabulut, H.; Gunduz, S.In this study, the effects of heat treatment on the microstructures and mechanical properties of powder metallurgy (PM) Nb-V microalloyed steels (Fe + 0.25%C + 0.075%Nb + 0.075%V) were investigated. Argon gas was used as sintering atmosphere. The microstructure and mechanical properties of the Nb-V added PM microalloyed steel were examined by optical microscopy, scanning electron microscope (SEM) and tensile tests. Experimental results showed that microalloyed steels can be produced by PM technology and the heat treatment affects the microstructure and mechanical properties of microalloyed PM steel. Nb-V microalloyed steels were heat treated under different conditions. Microstructures and tensile strengths of the samples were compared.Öğe Increasing the strength of AISI 430 ferritic stainless steel by static strain ageing(Redakcia Kovove Materialy, 2009) Kacar, R.; Gunduz, S.In this study, the strain ageing behaviour of AISI 430 ferritic stainless steel is investigated. A certain part of the as-received ferritic stainless steel test pieces was pre-strained for 5 % in tension, then aged at 100, 200, 300, and 400 degrees C for 30 min in a furnace. The other part was solution heat-treated at 950 degrees C for 15 minutes, water quenched and pre-strained for 2 or 5 % in tension, then aged at 100, 200, 300, and 400 degrees C for 30 min. UTS (ultimate tensile strength), Delta Y (increase in yield strength due to strain ageing), percentage elongation and yield point elongation measurements were employed to investigate the effect of strain ageing on the mechanical properties. The experimental work has revealed that different ageing temperatures significantly affect the mechanical properties of the AISI 430 ferritic stainless steel.Öğe Investigation of the effects of SiC reinforcement ratio in iron-based composite materials on corrosion properties(Southern African Inst Mining Metallurgy, 2022) Karabulut, H.; Erden, M. A.; Karacif, K.; Gunduz, S.The corrosion properties of iron-based composite materials containing graphite and silicon carbide (SiC) reinforcement were investigated. The effects of silicon carbide reinforcement were investigated by adding 0.5% graphite and 1%, 2%, and 4% SiC. A powder metallurgy method was used to produce the composite samples. Iron, graphite, and silicon carbide powders were blended for one hour with a three -axis mixer and then unidirectionally pressed under a pressure of 750 MPa. After pressing, the composite materials were sintered at 1100??C for one hour. The corrosion properties and microstructure, density, and hardness properties of the composite materials that can affect the corrosion properties were also investigated. It was determined that the pore ratio and hardness of the composite material increased, and corrosion resistance decreased, with increasing silicon carbide content.Öğe Martensite morphology and strain aging behaviours in intercritically treated low carbon steel(Taylor & Francis Ltd, 2011) Turkmen, M.; Gunduz, S.The strain aging behaviour of intercritically annealed low carbon steel with different martensite morphologies has been investigated. Aging experiments after 4% prestrain were carried out at 180 degrees C for different times ranging from 10 to 160 min. It was found that the variation in bake hardening response Delta Y, lower yield stress and ultimate tensile stress with aging time describes a similar trend for all three microstructural variants, but the absolute values of bake hardening response, lower yield stress and ultimate tensile stress are higher for the microstructure containing fibrous, more uniformly distributed martensite. The aging response of fibrous martensite was also found to be slower, and the fibrous martensite morphology provided the best combination of strength and ductility as desired for dual phase steels.Öğe Wear behaviour of sintered steels obtained using powder metallurgy method(Kaunas Univ Technol, 2017) Erden, M. A.; Gunduz, S.; Karabulut, H.; Turkmen, M.In this work, the hardness and abrasive-wear behaviour of powder metallurgy (PM) plain carbon steel and microalloyed steels with different amount of niobium or aluminium content (0.1-02 wt.-%) were investigated. It was found that steels microalloyed by niobium and aluminium have high hardness and wear resistance compared with the niobium and aluminium free steel. Wear behavior of these steels depends on the PM processing parameters and wear conditions. Worn surface pattern revealed the wear mechanism is ploughing. The surface exhibited extensive grooving occured as a result of ploughing by the harder SiC paper.
