Mehmet Akif Erden

Microstructural Effects on Fatigue Behaviour of a Forged Medium Carbon Microalloyed Steel

Abstract The effect of different microstructures on the fatigue behaviour of a medium carbon vanadium microalloyed steel has been studied. Specimens were subjected to a controlled closed die forging followed by cooling in sand, air or oil, respectively. The hardness and fatigue properties of the microalloyed steel are determined and compared with those of ferrite-pearlite and martensite microstructures obtained by cooling with different mediums after forging. Relatively fine ferrite and pearlite increase the fatigue strength of the steel, while the martensite structure reduces the fatigue strength. Characteristics of fatigue fracture surface morphology are summarized and related to fatigue crack initiation and propagation mechanisms in the forged medium carbon microalloyed steel. The cooling rate has a remarkable effect on the microstructure, hardness, and fatigue behaviour at room temperature.

Effect of vanadium addition on the microstructure and mechanical properties of low carbon micro-alloyed powder metallurgy steels

Abstract In the present experimental work, the effects of vanadium additions on the microstructures and mechanical properties of powder metallurgy (PM) steel and microalloyed powder metallurgy (PM) steels were investigated. The microstructures of the PM steel and microalloyed PM steels were characterized by optic microscope, SEM and EDS. Experimental results showed that vanadium microalloyed steels can be produced by PM technology. The addition of vanadium limits grain growth during austenitization prior to air cooling and increases the strength in the sintered conditions. By limiting austenite grain growth, the precipitates result in significant improvement in strength.

The Effect of Vanadium and Titanium on Mechanical Properties of Microalloyed PM Steel

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.

EFFECT OF TIN ADDITION ON THE MICROSTRUCTURE AND MECHANICAL PROPERTIES OF PM STEELS

In this work, the effects of TIN additions on the microstructures and tensile behaviors of microalloyed powder metallurgy (PM) steels were investigated. The microstructure of the microaloyed PM steels was characterized by optic microscope, SEM and EDS. Results indicated that the addition of TiN in the percentage of 0.1, 0.2 or 0.5 increases the yield strength (YS) and ultimate tensile strength (UTS) of the PM steels in the sintered conditions. Elongation also tends to improve with increasing TiN content. In addition, TiN prevented grain growth during sintering prior to cooling.

AlC İLAVE EDİLEN TOZ METAL ÇELİKLERDE KARBON ORANININ MİKROYAPI VE MEKANİK ÖZELLİKLER ÜZERİNE ETKİSİNİN ARAŞTIRILMASI

Bu calismada, toz metalurjisi(TM)ile uretilen AlC ilave edilmis celiklerde karbon oraninin mikroyapi and mekanik ozellikler uzerine etkisi arastirilmistir. Farkli karbon oranlarina sahip AlC ilave edilmis TM celik numuneler 750MPa presleme basincinda preslendikten sonra atmosfer kontrollu tup firinda argon atmosferinde 1350°C sicaklikta 1 saat sinterlenerek uretimi gerceklestirilmistir. Uretilen farkli karbon oranlarina sahip AlC ilave edilmis TM celiklerinin tane boyutu ve fazlarin dagilimi optik mikroskop ile belirlenirken, mekanik ozellikler cekme testi uygulanarak belirlenmistir. Sonuclar %0,55 karbon ilave edilmis mikroalasim celiginin en yuksek akma ve cekme dayanimi gosterdigi gozlenmistir.