The effect of silicon, vanadium and nitrogen on the microstructure and hardness of air cooled medium carbon low alloy steels

Abstract:In this work, the effects of NbC additions on the microstructure and mechanical properties were examined. In order to do this, NbC compounds were added into the Fe matrix at the weight percentage of 0.1-2 with individually to obtain powder mixture. The microstructure of the powder metallurgy (PM) steels were characterized by optic microscope, scanning electron microscope (SEM) and energy dispersive spectroscopy (EDS). Experimental results indicated that NbC alloyed steels can be produced by PM technology. An increase in strength was observed when the amount of NbC compounds increased for all PM steels. The precipitation of carbides and nitrides in these steels limits austenite grain growth and increases the precipitation hardening or clustering hardening that results in significant improvement in strength.

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“…This occurs when NbC, NbN, and NbC(N) precipitates, which formed during sintering process, prevent growth of the austenite grains [19].…”

Section: Alloymentioning

confidence: 99%

Influence of NbC Addition on the Sintering Behaviour of Medium Carbon PM Steels

Özdemirler

Gündüz

Erden

2017

Metals

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“…Table 2 shows that the grain size decreases as the ratio of BN increases up to 0.2 wt. % This situation takes place as the BN and BC(N) precipitates which are formed during sintering inhibit the growth of austenitic grains (Ollilainen et al 2003).…”

Section: Microstructurementioning

confidence: 99%

Effect of Boron Nitride Addition on the Microstructure and Mechanical Properties of PM Steels

Erden¹,

Türkmen²,

Karabulut³

et al. 2017

AKU-J. Sci. Eng.

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In this work, the effects of boron nitride additions on the microstructures and tensile behaviours of microalloyed powder metallurgy (PM) steels were investigated. The microstructure of the microalloyed PM steels was characterised by optic microscope, SEM and EDS. Results indicated that the addition of boron nitride in the percentage of 0.1 and 0.2 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 boron nitride content. In addition, the presence of boron nitride in different proportion prevented grain growth during sintering or cooling after sintering. However, a further increase in BN to 0.5 wt.% reduced the yield strength (YS), ultimate tensile strength (UTS), percentage elongation and hardness due to higher amount of precipitation strengthening. Toz Metal Çeliklerin Mikroyapı ve Mekanik Özelliklerine Bor Nitrürün Etkisi Anahtar kelimeler Toz Metal Çelikler, BorNitrür, Mikroyapı, Mekanik Özellikler. ÖzetBu çalışmada, Mikroalaşımlı Toz metal (TM) çeliklerin mikroyapı ve çekme davranışları üzerine bor nitrür ilavesinin etkileri incelenmiştir. Mikroalaşımlı TM çeliklerin mikroyapıları optik mikroskop, SEM ve EDS analizleri kullanılarak karakterize edilmiştir. Sonuçlar; yüzde 0,1 ve 0,2 oranında bor nitrür ilavesinin TM çeliklerin akma dayanımını (YS) ve çekme mukavemetini (UTS) artırdığını göstermiştir. Ayrıca % Uzama oranı bor nitrür ilavesinin artmasıyla artma eğilimindedir. Buna ek olarak, farklı oranda bor nitrür varlığı sinterleme sırasında veya sinterleme sonrasında tane büyümesini engellemiştir. Ancak ağırlıkça % BN oranını 0,5 olduğunda akma dayanımı (YS), çekme dayanımı (UTS), % uzama ve sertlik değeri çökelme sertleşmesine bağlı olarak azalmıştır.

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“…Ductility and toughness show a significant increase with a reduction in finishing temperature [8]. Also chemical composition plays an important role in microalloyed steels: many studies were carried out about the influence of increasing V, Nb, N and Si concentration on the microstructure and mechanical properties of these steels [9,10]. One of the most important processing factors affecting the properties of medium C microalloyed steels is the post deformation cooling procedure.…”

Section: Introductionmentioning

confidence: 99%