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Showing 3 results for Grain Size

M. Esmailian,
Volume 7, Issue 1 (3-2010)
Abstract

Abstract:

transformation temperature and different ferrite morphologies in one Nb-microalloyed (HSLA) steel has been

investigated. Three different austenite grain sizes were selected and cooled at two different cooling rates for obtaining

austenite to ferrite transformation temperature. Moreover, samples with specific austenite grain size have been

quenched, partially, for investigation on the microstructural evolution.

In order to assess the influence of austenite grain size on the ferrite transformation temperature, a temperature

differences method (TDM) is established and found to be a good way for detection of austenite to ferrite, pearlite and

sometimes other ferrite morphologies transformation temperatures.

The results obtained in this way show that increasing of austenite grain size and cooling rate has a significant influence

on decreasing of the ferrite transformation temperature.

Micrographs of different ferrite morphologies show that at high temperatures, where diffusion rates are higher, grain

boundary ferrite nucleates. As the temperature is lowered and the driving force for ferrite formation increases,

intragranular sites inside the austenite grains become operative as nucleation sites and suppress the grain boundary

ferrite growth. The results indicate that increasing the austenite grain size increases the rate and volume fraction of

intragranular ferrite in two different cooling rates. Moreover, by increasing of cooling rate, the austenite to ferrite

transformation temperature decreases and volume fraction of intragranular ferrite increases.

The effect of different austenite grain size and different cooling rates on the austenite to ferrite

M. Alipour, S. Mirjavadi, M. K. Besharati Givi, H. Razmi, M. Emamy, J. Rassizadehghani,
Volume 9, Issue 4 (12-2012)
Abstract

In this study the effect of Al–5Ti–1B grain refiner on the structural characteristics and wear properties of Al–12Zn–3Mg–2.5Cu alloy was investigated. The optimum amount for Ti containing grain refiners was selected as 2 wt.%. T6 heat treatment, (i.e. heating at 460 °C for 1 h before water quenching to room temperature and then aging at 120 °C for 24 h) was applied for all specimens before wear testing. Dry sliding wear resistant of the alloy was performed under normal atmospheric conditions. The experimental results showed that the T6 heat treatment considerably improved the resistance of Al–12Zn–3Mg–2.5Cu alloy to dry sliding wear.
Amir Mostafapour, Milad Mohammadi, Ali Ebrahimpour,
Volume 18, Issue 2 (6-2021)
Abstract

A full factorial design of experiment was applied running 36 experiments to investigate the effects of milling parameters including cutting speed with three levels of 62.83, 94.24 and 125.66 m/min, feed rate with three levels of 0.1, 0.2 and 0.3 mm/tooth, cutting depth with two levels of 0.5 and 1 mm and machining media with two levels, on surface integration properties of magnesium AZ91C alloy such as grain size, secondary phase percent, surface microhardness and surface roughness. In all cases, a fine grained surface with higher secondary phase sediment and microhardness obtained comparing the raw material. According to analysis of variance results, the most effective parameter on grain size, secondary phase percent and microhardness was cutting depth and the most effective parameter on surface roughness was feed rate. although the grain size in all machined samples was smaller than that of the raw material but due to the dual effect of cryogenic conditions, which both cool and lubricate and reduce the temperature and strain rate at the same time, the direct effect of this parameter on grain size was not significant. Also, the all interaction effects of parameters on grain size and microhardness were significant.

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