Design, construction, and performance of a device for directional recrystallization of metallic alloys

Abstract

A device was designed to apply the directional recrystallization method to Fe-based alloys in order to obtain bamboo-like microstructures. This microstructure is suitable for improving creep properties and resistance to fatigue in some alloys and for enhancing pseudoelastic properties in shape memory alloys. The design and construction of a flat coil are described in detail. In addition, we developed an electromechanical system to control the movement of a wire within the flat coil. The construction details and system performance are presented. Furthermore, metallographic studies taken from the directionally recrystallized low-carbon steel samples are shown. Nearly monocrystalline and bamboo-like microstructures were achieved in the steel wires.

Directional recrystallisation processing: a review

“…The heating source, cooling method and temperature gradient noted in various papers are listed in Table 2. For furnaces where the heating unit moves when the sample is static [6,18,[20][21][22][23]25,28,30,31,33,35,50], the temperature gradient often changes continuously during processing since the distance between the heating unit and heat sink changes; while for furnaces where the sample travels when the heating unit is static [8,[35][36][37][38][39][40][41][43][44][45][46]48,49,[52][53][54][55][56][57][58], the temperature gradient is usually constant as long as the sample is long enough. It is clear that static heating unit design is better for directional recrystallisation research since the temperature gradient is well controlled.…”

“…A transverse temperature gradient can be present in some directional annealing studies, especially with large samples and using induction heating, in which a transverse temperature gradient is induced by the skin effect. Using the finite element method, Liu et al [54] showed that for a five-turn induction coil furnace (cross-section of 60 × 60 mm 2 ), a transverse temperature gradient was observed when the iron sample diameter was larger than 20 mm and that it increased with increasing sample Air-impingement cooling 844 [15] Induction coil Ambient air cooling 25 [35] Focused light radiation Ambient air cooling 50 [35][36][37]43,53,53,55,56] Focused light radiation Water-cooled copper 1000 [38][39][40][41][42]44,48] Induction coil Liquid Ga-In cooling bath 200-350 [45,47] Resistance heating Ambient air cooling 82 [46] Induction coil Water cooling bath 900 [49] Induction coil Water-cooled chill block 200 [55] Induction coil Water cooling bath 680 [57] Induction coil Ambient air cooling 180 diameter. Thus, a transverse temperature gradient can undoubtedly affect the directional recrystallised structure in different parts of the material.…”

“…Note that the temperature gradient along the drawing direction depends on the experimental set-up used for directional recrystallisation. Usually, the temperature gradient of air-cooled furnaces is tens to several hundreds of K cm −1 [7][8][9]15,26,35,36,45,47,57] while furnaces designed with a heat sink can provide a temperature gradient from 100 to 1000 K cm −1 [3][4][5][6]8,[35][36][37][38][39][40][41][42][43][44]46,48,49,52,53,55,56], depending on the furnace layout and cooling system. The heating source, cooling method and temperature gradient noted in various papers are listed in Table 2.…”

Alternative Thermal Cycling Treatment to Produce Abnormal Grain Growth in FeMnAlNi Alloys: Study of Composition Variations and Effects on the Relative Phase Stabilities

“…On the other hand, pseudoelasticity reaches a large efficiency if single crystals are considered [15,22,23]. In this way, Vallejos et al developed a method based on thermal cycling with a simultaneous directional annealing, which leads to single crystals after a short time interval [24,25].…”