Formation of Ultra Fine Ferrite and Determination of Critical Strain in the Strain Induced Dynamic Transformation for 0.22C-Mn Steel

Sang Min Lee; Young Jae Kwon; Duk Lak Lee; Sang Hyun Cho; Sun Keun Hwang; Yeon Chul Yoo

doi:10.4028/www.scientific.net/MSF.510-511.514

Paper Titles

The Effect of Cold Equal Channel Angular Process on Texture of Magnesium Alloy (AZ31)
p.498

Kinetic Analysis of the Decomposition of Calcium Carbonate Using Danyang Limestone
p.502

Effect of Frit Content in Ag Paste and Thickness of Transparent Dielectric on Yellowing Phenomenon
p.506

Effect of Thermo-Mechanical Variables on the Dynamic Ferrite Transformation Induced by Hot Deformation in 0.22C-Mn Steel
p.510

Formation of Ultra Fine Ferrite and Determination of Critical Strain in the Strain Induced Dynamic Transformation for 0.22C-Mn Steel
p.514

Prediction of Flow Curves and Micro-Structural Evolution in Strain Induced Dynamic Transformation of Low Carbon Steel
p.518

Textures and Mechanical Properties of Melt-Extruded Al-Cu Alloys
p.522

Effect of Electromagnetic Stirring on Orientation Distribution Function of Primary Solid Phase of Al-Cu Alloy
p.526

Cell Sensing Margin of Lead-Free (Bi,La)₄Ti₃O₁₂Thin Film Deposited on MTP Cell Structure in High Density FeRAM Device
p.530

HomeMaterials Science ForumMaterials Science Forum Vols. 510-511Formation of Ultra Fine Ferrite and Determination...

Formation of Ultra Fine Ferrite and Determination of Critical Strain in the Strain Induced Dynamic Transformation for 0.22C-Mn Steel

Abstract:

The low carbon steel of 0.22wt% carbon was tested to estimate the dynamic phase transformation behavior from austenite to ferrite. The samples were deformed at just above Ar3 temperature by hot torsion at condition of strain rate (0.5/sec) and strain (5.0). The flow curve obtained at just above Ar3 significantly differed from others due to dynamic transformation. Based on the analysis of flow stress curve and observation of micro-structure evolution, the initiation and finish points of strain induced dynamic transformation (SIDT) could be determined. An inflection point observed at early deformation range (0.2–0.3) from the work-hardening rate and stress plot meant that new ferrite grains were nucleated in austenite matrix and these nuclei could be also confirmed by optical microscope. Subsequently in strain range of 0.7-1.0, the flow stress had the maximum value and new fine ferrite grains were dynamically generated inside untransformed austenite grains as well as prior austenite grains. The dynamic phase transformation induced by deformation made eventually fine ferrite grains under 3 ㎛ and decreased stress level with a fixed gradient.