Factors Affecting Texture Memory Appearing through α→γ→α Transformation in IF Steels

Abstract

In case where IF steel is heat treated in region, ! and ! transformation during heating and cooling, i.e. ! ! transformation, take place during heating and cooling, respectively. The initial texture of is potentially weakened due to two times transformation in general. On the contrary, the ! ! transformed texture resembles the initial texture clearly under specific circumstances. Authors call this phenomenon ''texture memory''. A very distinct texture memory effect was found in IF steels. Lowering the ! transformation temperature pronounces texture memory significantly. The variant selection at grain boundary of seems to play an important role. Moreover, it is considered that the initial texture has to be sharp to in order to realize texture memory.

Reconstruction of the Three-dimensional Ferrite–austenite Microstructure and Crystallographic Analysis in the Early Stage of Reverse Phase Transformation in an Fe–Mn–C Alloy

“…The variant selection of austenite during reverse transformation has been discussed in the literatures and several models have been proposed. [3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19] Tomida et al proposed the variant selection model to predict the texture change in α→γ transformation based on the orientation relationships at multiple interfaces with different ferrite grains. 9,10) In these studies, the variant of austenite is assumed to be selected to simultaneously satisfy the Kurdjumov-Sachs (K-S) relationship 20) with one ferrite grain and an orientation relationship near the K-S relationship with about 10° of the tolerance angle with other adjoining ferrite grains.…”

“…For example, ferrite-to-austenite transformation occurring in an intercritical annealing range is known to indicate the memory effect. [3][4][5][6] There must be a rule that determines austenite orientation in relation to the initial ferrite texture. The variant selection of austenite during reverse transformation has been discussed in the literatures and several models have been proposed.…”

Establishment and Optimization of Angle Dispersive Neutron Diffraction Bulk Texture Measurement Environments

“…These {111}h112i and {001}h110i components are speculated to directly transform into austenite during rapid heating and then to transform backward into martensite during air cooling to room temperature. That is to say, the texture memory effect 25) possibly occurred during the rapid annealing. In Figs.…”

Transformation Texture in Hot-rolled Steel Sheets and Its Quantitative Prediction

“…If it is assumed that the double K-S relation should be precisely fulfilled, this relation is realized only at the special boundaries such as twin boundaries and low angle boundaries in γ . 10,25) However, if a certain deviation from the K-S relation is permitted, it is possible that the variants that fulfill the double K-S relation appear at ordinary boundaries. For example, if the deviation up to 10° is permitted for the relation between α and one neighboring γ grain, while the exact K-S relation is still fulfilled between the α and the other γ gain on the opposite side, then the double K-S relation can be fulfilled at general grain boundaries at about 70% of probability.…”

“…It has been reported that the double KS relation may play an important role in the texture memory effects in α -γ -α transformation. 25,26) The double K-S relation has been modeled to mathematically adopt it into the MODF method as follows. (1) As α nucleates on the high angle grain boundaries of γ , the variants of α that hold the K-S relation with two adjoining γ grains are preferentially activated.…”