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Showing 3 results for H. Saghafian
EFFECT OF SILICON CONTENT ON THE STRAIN HARDENING OF DUAL-PHASE STEELS
A.nouri, Sh.kheirandish, H. Saghafian,
Volume 5, Issue 4 (Autumn 2008 2008)
Abstract
Abstract: In the current work, the strain hardening behavior of dual-phase steels with different silicon content (0.34- 2.26 Wt. %) was examined using the modified Crussard-Jaoul analysis. It was shown that these dual-phase steels deform in two stages over a uniform strain range. Each stage exhibited a different strain hardening exponent varying with silicon content. At the first stage, work hardening exponent remind significantly constant, while during the second stage, it decreased with increasing silicon content from 0.34% to 1.51% and then increased for the higher silicon contents (1.51% to 2.26%). It was found that the strain hardening behavior of these steels was predominantly affected by the volume fraction of martensite at low silicon contet and the ferrite strengthening induced by silicon at the higher silicon content. The effect of silicon content on the volume fraction of martensite and tensile properties were also considered.
EFFECT OF GRAPHITE FLAKES ON THE MICROSTRUCTURE OF MELTED, TRANSITION AND HEAT AFFECTED ZONES IN GREY CAST IRON REMELTED BY TIG
H. Mohammadzade, Sh. Kheirandish, H. Saghafian,
Volume 6, Issue 2 (Spring 2009 2009)
Abstract

Abstract:

transition and heat affected zones formed during surface remelting (in order to improve wear resistance) with TIG

process has been investigated. Relationship between various TIG parameters and thickness of remelted and heat

affected zones revealed that a high concentrated heat energy is imposed by TIG process which makes it a proper option

for focused surface treatment. Based on microstructural examinations five areas with different microstructure and

microhardness were identified within the surface area. Graphite flakes were totally dissolved within the first area

leading to the transformation of denderitic austenite to plate martensite and the formation of ledeburite within

interdenderites. The main feature of the second area, resulted from the presence of graphite flakes, was the local

melting with a gap in the vicinity of graphite flakes and that of third area was the formation of finer and denser

martensite plates closer to the graphite flakes compared with those formed at a further distance. In the fourth layer

there is a mixture of martensitic and pearlitic matrix while the matrix of fifth layer has no change of microstructure.

In this study the effect of graphite flakes present in a pearlitic grey cast iron on the microstructure of melted,
EVALUATION OF THE MECHANICAL PROPERTIES OF NIOBIUM MODIFIED CAST AISI H 13 HOT WORK TOOL STEEL
A. Noorian, Sh. Kheirandish, H. Saghafian,
Volume 7, Issue 2 (Spring 2010 2010)
Abstract

Abstract:

mechanical properties of AISIH 13 hot-work tool steel have been studied. Cast samples made of the modified new steel were homogenized and austenitized at different conditions, followed by tempering at the specified temperature ranges. Hardness, red hardness, three point bending test and Charpy impact test were carried out to evaluate the mechanical properties together with characterizing the microstructure of the modified steel using scanning electron microscope. The results show that niobium addition modifies the cast structure of Nb–alloyed steel, and increases its maximum hardness. It was found that bending strength bending strain, impact strength, and red hardness of the modified cast steel are also higher than those of the cast H13 steel, and lower than those of the wrought H13 steel.

In this research, the effects of partially replacing of vanadium and molybdenum with niobium on the
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