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Effect of equal channel angular pressing on structure and mechanical properties of a low carbon steel
Author(s) -
Shin Dong Hyuk,
Jeong Won Sik,
Kim Jongryoul,
Paik YoungNam
Publication year - 2001
Publication title -
steel research
Language(s) - English
Resource type - Journals
eISSN - 1869-344X
pISSN - 0177-4832
DOI - 10.1002/srin.200100092
Subject(s) - misorientation , materials science , microstructure , pearlite , pressing , lamellar structure , ferrite (magnet) , carbon steel , grain boundary , composite material , grain size , metallurgy , austenite , corrosion
Experiments were conducted on a plain low carbon steel with an initial grain size of ~ 30μm to investigate the changes of microstructure and mechanical properties by repetitive equal channel angular pressings. Under the pressing conditions of giving a strain of ~ 1 and rotating samples 180° between each pass, the yield strength significantly increases from 310 to 750 MPa after single pass, and it reaches 1050 MPa after 12 passes. The increment of yield strength gradually decreases as the number of passes increases. The examination of microstructure by transmission electron microscopy shows that ferrite consists of parallel bands of elongated subgrains having a width of 0.3 μm and a length of 2 μm after a single pass. The subgrains are further divided by boundaries with low angle misorientation on subsequent passages. Low angle boundaries turn to high angle boundaries without noticeable grain refinement as the number of pass increases. In addition, lamellar cementites in pearlite are broken up into fragments within a pearlite colony. Analyses of structural and mechanical changes in a plain low carbon steel by equal channel angular pressing indicate that the strength enhancement is mainly due to the grain refinement of ferrite.