Mechanical properties of as-cast microalloyed steels produced via investment casting

Najafi, Hamidreza; Rassizadehghani, J.; Norouzi, Saeid

doi:10.1016/j.matdes.2010.08.007

Cited by 20 publications

(8 citation statements)

References 22 publications

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“…Brittle crack initiation is probably associated with carbide particles at boundaries for bainite and martensite microstructures. It is in accordance with previous fractography study [29] on Charpy V-notch impact tests which showed that microalloying elements can change the fracture mode from ductile to brittle.…”

Section: Resultssupporting

confidence: 93%

Effect of heat treatment on Charpy impact energy of microalloyed steel

et al. 2016

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Original scientific paper In this paper the microalloyed high-strength low-alloy (HSLA) Niomol 490K steel with an addition of niobium (0,032 wt. %) has been investigated. Heat treatment of the steel consisted of austenitisation at 1250 °C for 3 minutes and reheating up to 750 °C for 5 s. After austenitization the quenching was carried out in water with temperature of 70 °C and then in a lead bath up to 400 °C following cooling on the air. It was found that Charpy impact energy is higher and the transition temperature is lower for the transformation of austenite to bainite than to martensite microstructure. Experimental results showed that different fracture surface was observed. It is shown that preferred cleavage fracture occurred in the lattice plane (001) Utjecaj toplinske obrade na Charpy energiju udara mikrolegiranog čelikaIzvorni znanstveni rad U ovom radu istraživan je niskolegirani visokočvrsti čelik Niomol 490K koji sadrži dodatak niobija (0,032 mas. %). Toplinska obrada čelika se sastojala od austenitizacije pri 1250 °C u trajanju od 5 minuta i ponovnog zagrijavanja do 750 °C u trajanju od 5 s. Nakon austenitizacije provedeno je kaljenje u vodi kod temperature od 70 °C i u olovnoj kupci do temperature od 400 °C uz naknadno hlađenje na zraku. Utvrđeno je da je Charpy energija udara viša, a prijelazna temperatura niža za transformaciju austenita u bainit nego kod transformacije austenita u martenzitnu mikrostrukturu. Eksperimentalni rezultati su pokazali različite prijelomne površine. Pokazano je da je preferentno cijepajući prijelom zapažen po ravnini rešetke (001), neovisno o mikrostrukturi.

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Section: Resultssupporting

confidence: 93%

Effect of heat treatment on Charpy impact energy of microalloyed steel

et al. 2016

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“…They found that Si and Ti additions show positive effect in increasing the strength and refining the austenite grain size, respectively. As reported by Najafi et al [12], the presence of microalloying elements significantly enhanced the strength of as-cast microalloyed steels due to the formation of fine-scale precipitates. The work of Han et al [13] indicated that precipitates affect the hot ductility of microalloyed steels.…”

Section: Introductionmentioning

confidence: 53%

Effects of tungsten on continuous cooling transformation characteristics of microalloyed steels

et al. 2013

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Continuous cooling transformation (CCT) characteristics of microalloyed steels with different tungsten (W) contents (0, 0.1 and 1. wt.%) were investigated to obtain the necessary information for heat treatment of these steels. The effects of W addition on the sizes of prior austenite grains and precipitates were analysed. CCT diagrams were obtained by varying the cooling rates from 0.1 to 120. °C/s. Transformation characteristics were determined by using dilatometer test, microscopic observation and hardness measurement. The results showed that W had a positive effect on the refinement of prior austenite grains and precipitates. The CCT diagrams exhibited that the ranges of transformation products were shifted to the right side of the diagram when the W content increased. CCT diagram for steel with 0.1% W was similar in shape to that without W. The addition of 1% W induced two separated transformation ranges in the cooling rate range of 0.1 to 1. °C/s in the diagram. Both the austenitisation starting and finishing temperatures were raised as W was added. W addition induced decreased critical cooling rates for phase transformations and obtaining complete ferrite + pearlite microstructures. The martensite transformation temperature was decreased after W addition. The addition of W caused increased hardness, and the hardness obeyed an exponential type relationship with cooling rate. contents (0, 0.1 and 1 wt.%) were investigated to obtain the necessary information for heat treatment of these steels. The effects of W addition on the sizes of prior austenite grains and precipitates were analysed. CCT diagrams were obtained by varying the cooling rates from 0.1 to 120℃/s. Transformation characteristics were determined by using dilatometer test, microscopic observation and hardness measurement. The results showed that W had a positive effect on the refinement of prior austenite grains and precipitates. The CCT diagrams exhibited that the ranges of transformation products were shifted to the right side of the diagram when the W content increased. CCT diagram for steel with 0.1% W was similar in shape to that without W.The addition of 1% W induced two separated transformation ranges in the cooling rate range of 0.1 to 1℃/s in the diagram. Both the austenitisation starting and finishing temperatures were raised as W was added. W addition induced decreased critical cooling rates for phase transformations and obtaining complete ferrite+pearlite microstructures. The martensite transformation temperature was decreased after W addition.The addition of W caused increased hardness, and the hardness obeyed an exponential type relationship with cooling rate.

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“…3 and on the austenitising temperature at 1000 °C in Fig. 4 [35,36]. The austenite grain size of the as-cast microalloyed steels were investigated using Spektor's analysis in order to determine the size distribution.…”

Section: Resultsmentioning

confidence: 99%