“…These precipitations have been stated to limit austenite grain growth and increase material strength with precipitation hardening. 17,34,35 Figure 8.SEM microstructure EDS results of Cr steel samples containing (a) wt. % 5 Mo and (b) wt.…”
Section: Resultsmentioning
confidence: 99%
“…These precipitations have been stated to limit austenite grain growth and increase material strength with precipitation hardening. 17,34,35 The effect of alloying elements in sediment on the recrystallization of austenite is too weak. The inhibition of grain boundary movement by precipitated particles is much greater than the effect of solute atoms.…”
Section: Microstructure and Mechanical Properties Of Mo-added Cr Pm S...mentioning
In this work, it was investigated the effect of molybdenum (Mo) addition on machinability, mechanical properties, and microstructure of Cr steels produced by using powder metallurgy method. Tensile and hardness experiments were applied to define the mechanical properties of the produced Cr-PM steels. The machining experiments have been also performed without coolant on a CNC vertical machining center at three different cutting speeds (150, 210, and 270 m/min), two different feed rates (0.4 and 0.8 mm/tooth), and constant depth of cut (0.5 mm). The machinability of the alloys was evaluated in regard to surface roughness (Ra) and tool wear (Vb). The results indicated that that Cr-PM steel with 5% Mo addition by weight had the highest yield, tensile strength, and hardness, and the best surface quality was obtained in this sample in terms of surface roughness. However, according to Vb measurement results, the cutting performance of the cutting inserts wasnegative affected by MoC(N), CrC(N), and MoCrC(N) precipitates formed in the microstructure of PM steel.
“…These precipitations have been stated to limit austenite grain growth and increase material strength with precipitation hardening. 17,34,35 Figure 8.SEM microstructure EDS results of Cr steel samples containing (a) wt. % 5 Mo and (b) wt.…”
Section: Resultsmentioning
confidence: 99%
“…These precipitations have been stated to limit austenite grain growth and increase material strength with precipitation hardening. 17,34,35 The effect of alloying elements in sediment on the recrystallization of austenite is too weak. The inhibition of grain boundary movement by precipitated particles is much greater than the effect of solute atoms.…”
Section: Microstructure and Mechanical Properties Of Mo-added Cr Pm S...mentioning
In this work, it was investigated the effect of molybdenum (Mo) addition on machinability, mechanical properties, and microstructure of Cr steels produced by using powder metallurgy method. Tensile and hardness experiments were applied to define the mechanical properties of the produced Cr-PM steels. The machining experiments have been also performed without coolant on a CNC vertical machining center at three different cutting speeds (150, 210, and 270 m/min), two different feed rates (0.4 and 0.8 mm/tooth), and constant depth of cut (0.5 mm). The machinability of the alloys was evaluated in regard to surface roughness (Ra) and tool wear (Vb). The results indicated that that Cr-PM steel with 5% Mo addition by weight had the highest yield, tensile strength, and hardness, and the best surface quality was obtained in this sample in terms of surface roughness. However, according to Vb measurement results, the cutting performance of the cutting inserts wasnegative affected by MoC(N), CrC(N), and MoCrC(N) precipitates formed in the microstructure of PM steel.
“…Figure 3a shows the microstructure of the sample formed by uniaxial pressing at room temperature and as in other studies [26][27], it was sintered at 1150 ° C temperature in Ar atmosphere. As seen from the microstructure, the expected primary cementite and perlite coverslips are seen in the sample after sintering.…”
Section: Fig 2 Graphic Of Density Variation Of Specimensmentioning
confidence: 93%
“…It is necessary to produce hard phases in a microstructure to increase wear resistance. To do this, the most common heat treatment applied to PM carbon steels is quenching + tempering [13][14][15][16].…”
In this study, 1.5% by weight of natural graphite powders were added to Atomet 1001 pure iron powders and unalloyed high carbon powder metallurgy steel specimens were obtained. After the mixture was uniaxial pressed at room temper-ature and 700 Mpa pressing pressure, it was sintered in Ar protected atmosphere controlled oven at 1150 ° C for 20 minutes. The densities of the specimens before and after sintering were measured using precision scales and electronic calipers and presented graphically. After sintering, microstructure specimens containing primary cementite and typical dense perlite colonies were produced. The sintered specimens having primary cementite plus lamellar pearlitic structures were fully quenched from 950 °C temperature and then over-tempered at 705 °C temperature for 60 minutes to produce spherical-fine cementite particles in the ferritic matrix. After by this treatment, these specimens annealed at 735 °C temperature for 3 minutes were austempered at 300 °C salt bath for a period of 1 to 5 hours. After the heat treatment, dry sliding wear tests of specimens were carried out under 10N constant load and 500-1500m wear distance. At the end of the dry sliding wear test, the weight losses of the specimens were measured and it was determined that the dry sliding wear resistance increased with increasing austempering time after spheroidization annealing.
“…TM ile üretimin; diğer (döküm, kaynak, talaşlı imalat ve plastik şekil verme vb.) yöntemlerle üretilmesi zor veya üretilemez olan çeşitli alaşımların üretilebilmesi, malzeme kaybının oldukça az olması, üretim hızının yüksek olması, hassasiyet gerektiren karmaşık şekilli parçaların üretilebilmesi, üretilen malzemelerde yüksek (fiziksel ve mekanik) özellikler gibi birçok üstünlükleri vardır [6,9,10,11]. Tüm bahsedilen bu üstün özellikler TM ile yapılan çalışmaların önemini artırmaktadır.…”
ÖZAl2024 matrisli Si takviyeli kompozitler, Al2024 alaşım tozlarının içerisine ağırlıkça ayrı ayrı %5, 10 ve 15 oranında Si ilavesi yapılarak klasik Toz Metalürjisi yöntemiyle üretilmiştir. Tozlar 0,0001 hassasiyetli terazi ile tartılarak, üç eksenli karışım yapan turbulo cihazında bir saat süreyle karıştırılmıştır. Elde edilen karışım tozlar 12 mm çapında 10 mm yüksekliğinde blok oluşturacak şekilde tek eksenli pres ile blok haline getirilmiştir. Blok haline getirilen numuneler kademeli olarak önce 300°C'de 30 dakika, ardından 590°C'de 90 dakika bekletilerek sinterlenmiştir. Üretilen numunelere farklı parametrelerde yaşlandırma işlemi uygulanarak, kompozitlerde yaşlandırma süresinin ve Si miktarının sertlik özelliklerine etkisi incelenmiştir.Anahtar Kelimeler: Kompozit, Al2024, sertlik
EFFECT OF THE AMOUNT OF Si AND AGING DURATIONS IN Al2024-Si ALLOYED COMPOSITES PRODUCED BY POWDER METALLURGY METHOD ABSTRACTIn the present paper, different weight fractions of 5, 10 and 15% Si particles reinforced Al2024 matrix composites were prepared by the powder metallurgy method. The powders were prepared using a digital weighing scale with a precision of 0.0001. The powders were stirred with turbulo machine for 1 hour. Homogeneously mixed powders were pressed to form 12 mm in diameter and 10 mm height block in one direction. The pressed samples were sintered gradually first at 300ºC for 30 min then 590°C for 90 min in an argon atmosphere. Sintered samples were applied aging treatment by different parameters. The effects of Si addition and aging time on hardness behaviour of composites have been investigated.
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