TY - JOUR
T1 - Effect of Strain-Induced Age Hardening on Yield Strength Improvement in Ferrite-Austenite Duplex Lightweight Steels
AU - Song, Hyejin
AU - Lee, Seok Gyu
AU - Sohn, Seok Su
AU - Kwak, Jai Hyun
AU - Lee, Sunghak
N1 - Funding Information:
This work was supported by the Ministry of Knowledge Economy of Korea under a Grant No. 10052826 and BK21 Plus Center for Creative Industrial Materials.
Publisher Copyright:
© 2016, The Minerals, Metals & Materials Society and ASM International.
PY - 2016/11/1
Y1 - 2016/11/1
N2 - Ferrite-austenite lightweight steels showing TRansformation-induced plasticity were developed by varying the aging temperature with or without prestraining, and their effects on tensile properties were investigated in relation with microstructural evolution of carbide formation. The aged steels contained austenite, pearlite, and martensite in the ferrite matrix, and the austenite volume fraction decreased with the increasing aging temperature because some austenite grains decomposed to pearlites. This austenite decomposition to pearlite was favorable for the improvement of yield strength, but negatively influenced overall tensile properties. The prestraining promoted the austenite decomposition by a diffusion-controlled phase transformation, and changed the morphology of the cementite from a long lamellar shape to a densely agglomerated particle shape. In order to obtain the large increase in yield strength as well as excellent combination of strength and ductility, the strain-induced aging treatment, i.e., prestraining followed by aging, is important like in the prestrained and 673 K (400 °C)-aged steel. This large increase in yield strength, in spite of a reduction of elongation (65 to 43 pct), was basically attributed to an appropriate amount of decomposition of austenite to pearlite (e.g., 4 vol pct), while having sufficient austenite to martensite transformation (e.g., 14.5 vol pct martensite).
AB - Ferrite-austenite lightweight steels showing TRansformation-induced plasticity were developed by varying the aging temperature with or without prestraining, and their effects on tensile properties were investigated in relation with microstructural evolution of carbide formation. The aged steels contained austenite, pearlite, and martensite in the ferrite matrix, and the austenite volume fraction decreased with the increasing aging temperature because some austenite grains decomposed to pearlites. This austenite decomposition to pearlite was favorable for the improvement of yield strength, but negatively influenced overall tensile properties. The prestraining promoted the austenite decomposition by a diffusion-controlled phase transformation, and changed the morphology of the cementite from a long lamellar shape to a densely agglomerated particle shape. In order to obtain the large increase in yield strength as well as excellent combination of strength and ductility, the strain-induced aging treatment, i.e., prestraining followed by aging, is important like in the prestrained and 673 K (400 °C)-aged steel. This large increase in yield strength, in spite of a reduction of elongation (65 to 43 pct), was basically attributed to an appropriate amount of decomposition of austenite to pearlite (e.g., 4 vol pct), while having sufficient austenite to martensite transformation (e.g., 14.5 vol pct martensite).
UR - http://www.scopus.com/inward/record.url?scp=84982141354&partnerID=8YFLogxK
U2 - 10.1007/s11661-016-3706-1
DO - 10.1007/s11661-016-3706-1
M3 - Article
AN - SCOPUS:84982141354
SN - 1073-5623
VL - 47
SP - 5372
EP - 5382
JO - Metallurgical and Materials Transactions A: Physical Metallurgy and Materials Science
JF - Metallurgical and Materials Transactions A: Physical Metallurgy and Materials Science
IS - 11
ER -