<i>In-Situ </i>Texture Measurements by Synchrotron Radiation of TRIP Steel during an Austempering Treatment

Abstract

Texture formation during an austempering treatment of a TRIP-assisted steel was studied by in-situ texture measurements with a high energy source (synchrotron). Samples from a cold rolled sheet were subjected to a complete heat treatment cycle for TRIP steels including reheating to the intercritical (α+γ) temperature region, isothermal soaking and bainitic holding (austempering) at 400°C for 600s. At specific points of the thermal cycle {200}γ, {220}γ {222}γ, {331}γ and {200}α, {211}α and {220}α Debye rings were recorded and the corresponding incomplete pole figures were calculated. The latter were used to derive the orientation distribution functions (ODFs) of BCC and FCC phases at specific steps of the annealing process after assuming the orthotropic sample symmetry. The acquired data for the texture evolution during the α–γ–α phase transformation showed that during the reheating for intercritical annealing the gamma phase with {011} orientation is among the first to nucleate from the recrystallized α phase during heating and the Goss and Cube orientations are among the principal gamma phase components which transform to BCC phase after cooling.

Temperature Dependence of the Static and Dynamic Behaviour in a Quenching and Partitioning Processed Low-Si Steel

“…Points with CI < 0.1 were excluded from the data for texture calculation. The ODF ( Figure 5) shows a typical BCC transformation texture known as transformation BCC-beta fibre texture in which the product BCC texture originates from austenite with a Brass ({011}<211>), Goss ({011}<100>} and Cube ({001}<100>) texture [56][57][58]. The overall texture intensity is low, indicating that the material is not strongly textured with a maximum value of 1.35 multiples of random density (mrd).…”