Mustafa Türkmen

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.

Influence of ageing treatment on microstructure, mechanical properties and adhesive wear behaviour of 6063 aluminium alloy

Purpose – The paper aims to provide new observations about static strain ageing in aluminium (Al) alloys which are widely used in structural applications. Design/methodology/approach – The present work aims to provide theoretical and practical information to industries or researchers who may be interested in the effect of static strain ageing on mechanical properties of Al alloys. The data are sorted into the following sections: introduction, materials and experimental procedure, results and discussion and conclusions. Findings – Tensile strength, proof strength (0.2 per cent) and percentage elongation measurement were used to investigate the effect of strain ageing on the mechanical properties. Wear tests were performed by sliding the pin specimens, which were prepared from as-received, solution heat-treated, deformed and undeformed specimens after ageing, on high-speed tool steel (64 HRC). It is concluded that the variations in ageing time improved the strength and wear resistance of the 6063 Al alloy; ...

Radiographic inspection of AISI 420 steel friction welds

Abstract In this study, X-ray radiographic tests of AISI 420 steel welded by friction welding were studied. During the welding process, three different rotations, 700, 1000 and 1300, were employed while the other parameters such as friction pressure, friction time, upsetting-pressure and upsetting-duration were unchanged. After the completion of welding process, the welded joints were subjected to radiographic tests by X-raydiffraction. The result of the radiographic tests indicates that by increasing rotation speed the amount of flash and joining properties/performance increases in all samples. The best properties of the AISI 420 martensitic stainless steel joints were observed in samples welded at a rotation speed of 1300 (rpm). It has been determined that in harmony with the definition of welding defects and respective radiographic images, lack of fusion is the most common welding defect.

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.

Effect of Aging on the Microstructure and Mechanical Properties of Magnesium Alloy AZ31

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 400°C, water quenching, and aging at 180°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.