The Effects of Process Temperatures on the Microstructure and Tensile Properties of Warm-Stamped Nb-Bearing Medium-Mn Steel

Jae Hoon Nam; Jeongho Han; Young Kook Lee

doi:10.1007/s11661-019-05570-w

The Effects of Process Temperatures on the Microstructure and Tensile Properties of Warm-Stamped Nb-Bearing Medium-Mn Steel

Jae Hoon Nam, Jeongho Han, Young Kook Lee

Department of Materials Science and Engineering

Research output: Contribution to journal › Article › peer-review

8 Citations (Scopus)

Abstract

The effects of process temperatures for warm stamping, such as annealing (T_ann), austenitizing (T_aus), and stamping temperatures (T_s), on the tensile properties of Nb-bearing medium-Mn (5.9 wt pct) steel were investigated. The cold-rolled tensile specimens were first annealed at 650 °C to 750 °C, austenitized at 650 °C to 900 °C, held at T_s (500 °C to 700 °C), and then air-cooled to room temperature. Of the three process temperatures, only T_aus significantly influenced the tensile properties of medium-Mn steel; in the T_aus range of 650 °C to 900 °C, the amount of variation in yield strength (YS), ultimate tensile strength (UTS), and total elongation (TE) were 555 MPa, 570 MPa, and 20 pct, respectively. Particularly, when the specimens were austenitized at 730 °C to 790 °C, high YS (1060 to 1100 MPa), UTS (1760 to 1795 MPa), and TE (10.0 to 11.7 pct) were obtained due to fine-grained martensite embedded with nano-sized Nb carbides. The Nb-bearing medium-Mn specimen was successfully warm-stamped into a T-part of a B-pillar prototype at 600 °C without any cracks after austenitized at 750 °C for 5 minutes, and then air-cooled to room temperature. The warm-stamped Nb-bearing medium-Mn steel revealed the higher TE (~ 9.3 pct) than the hot-stamped 30MnB5 steel (5.3 pct) at the similar level of UTS (1855 to 1900 MPa).

Original language	English
Pages (from-to)	1098-1108
Number of pages	11
Journal	Metallurgical and Materials Transactions A: Physical Metallurgy and Materials Science
Volume	51
Issue number	3
DOIs	https://doi.org/10.1007/s11661-019-05570-w
Publication status	Published - 2020 Mar 1

Bibliographical note

Funding Information:
The authors are thankful to Dr. D. Kim and Mr. Y. Jeon at the Korea Institute of Industrial Technology (KITECH) for technical support of high-speed hydraulic press. J.-H. Nam is grateful for the financial support from the National Research Foundation of Korea (NRF) Grant funded by the Korean Government (NRF-2016-Global Ph.D. Fellowship Program).

Funding Information:
The authors are thankful to Dr. D. Kim and Mr. Y. Jeon at the Korea Institute of Industrial Technology (KITECH) for technical support of high-speed hydraulic press. J.-H. Nam is grateful for the financial support from the National Research Foundation of Korea (NRF) Grant funded by the Korean Government (NRF-2016-Global Ph.D. Fellowship Program).

Publisher Copyright:
© 2019, The Minerals, Metals & Materials Society and ASM International.

All Science Journal Classification (ASJC) codes

Condensed Matter Physics
Mechanics of Materials
Metals and Alloys

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10.1007/s11661-019-05570-w

Cite this

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title = "The Effects of Process Temperatures on the Microstructure and Tensile Properties of Warm-Stamped Nb-Bearing Medium-Mn Steel",

abstract = "The effects of process temperatures for warm stamping, such as annealing (Tann), austenitizing (Taus), and stamping temperatures (Ts), on the tensile properties of Nb-bearing medium-Mn (5.9 wt pct) steel were investigated. The cold-rolled tensile specimens were first annealed at 650 °C to 750 °C, austenitized at 650 °C to 900 °C, held at Ts (500 °C to 700 °C), and then air-cooled to room temperature. Of the three process temperatures, only Taus significantly influenced the tensile properties of medium-Mn steel; in the Taus range of 650 °C to 900 °C, the amount of variation in yield strength (YS), ultimate tensile strength (UTS), and total elongation (TE) were 555 MPa, 570 MPa, and 20 pct, respectively. Particularly, when the specimens were austenitized at 730 °C to 790 °C, high YS (1060 to 1100 MPa), UTS (1760 to 1795 MPa), and TE (10.0 to 11.7 pct) were obtained due to fine-grained martensite embedded with nano-sized Nb carbides. The Nb-bearing medium-Mn specimen was successfully warm-stamped into a T-part of a B-pillar prototype at 600 °C without any cracks after austenitized at 750 °C for 5 minutes, and then air-cooled to room temperature. The warm-stamped Nb-bearing medium-Mn steel revealed the higher TE (~ 9.3 pct) than the hot-stamped 30MnB5 steel (5.3 pct) at the similar level of UTS (1855 to 1900 MPa).",

author = "Nam, {Jae Hoon} and Jeongho Han and Lee, {Young Kook}",

note = "Funding Information: The authors are thankful to Dr. D. Kim and Mr. Y. Jeon at the Korea Institute of Industrial Technology (KITECH) for technical support of high-speed hydraulic press. J.-H. Nam is grateful for the financial support from the National Research Foundation of Korea (NRF) Grant funded by the Korean Government (NRF-2016-Global Ph.D. Fellowship Program). Funding Information: The authors are thankful to Dr. D. Kim and Mr. Y. Jeon at the Korea Institute of Industrial Technology (KITECH) for technical support of high-speed hydraulic press. J.-H. Nam is grateful for the financial support from the National Research Foundation of Korea (NRF) Grant funded by the Korean Government (NRF-2016-Global Ph.D. Fellowship Program). Publisher Copyright: {\textcopyright} 2019, The Minerals, Metals & Materials Society and ASM International.",

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doi = "10.1007/s11661-019-05570-w",

language = "English",

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The Effects of Process Temperatures on the Microstructure and Tensile Properties of Warm-Stamped Nb-Bearing Medium-Mn Steel. / Nam, Jae Hoon; Han, Jeongho; Lee, Young Kook.
In: Metallurgical and Materials Transactions A: Physical Metallurgy and Materials Science, Vol. 51, No. 3, 01.03.2020, p. 1098-1108.

Research output: Contribution to journal › Article › peer-review

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T1 - The Effects of Process Temperatures on the Microstructure and Tensile Properties of Warm-Stamped Nb-Bearing Medium-Mn Steel

AU - Nam, Jae Hoon

AU - Han, Jeongho

AU - Lee, Young Kook

N1 - Funding Information: The authors are thankful to Dr. D. Kim and Mr. Y. Jeon at the Korea Institute of Industrial Technology (KITECH) for technical support of high-speed hydraulic press. J.-H. Nam is grateful for the financial support from the National Research Foundation of Korea (NRF) Grant funded by the Korean Government (NRF-2016-Global Ph.D. Fellowship Program). Funding Information: The authors are thankful to Dr. D. Kim and Mr. Y. Jeon at the Korea Institute of Industrial Technology (KITECH) for technical support of high-speed hydraulic press. J.-H. Nam is grateful for the financial support from the National Research Foundation of Korea (NRF) Grant funded by the Korean Government (NRF-2016-Global Ph.D. Fellowship Program). Publisher Copyright: © 2019, The Minerals, Metals & Materials Society and ASM International.

PY - 2020/3/1

Y1 - 2020/3/1

N2 - The effects of process temperatures for warm stamping, such as annealing (Tann), austenitizing (Taus), and stamping temperatures (Ts), on the tensile properties of Nb-bearing medium-Mn (5.9 wt pct) steel were investigated. The cold-rolled tensile specimens were first annealed at 650 °C to 750 °C, austenitized at 650 °C to 900 °C, held at Ts (500 °C to 700 °C), and then air-cooled to room temperature. Of the three process temperatures, only Taus significantly influenced the tensile properties of medium-Mn steel; in the Taus range of 650 °C to 900 °C, the amount of variation in yield strength (YS), ultimate tensile strength (UTS), and total elongation (TE) were 555 MPa, 570 MPa, and 20 pct, respectively. Particularly, when the specimens were austenitized at 730 °C to 790 °C, high YS (1060 to 1100 MPa), UTS (1760 to 1795 MPa), and TE (10.0 to 11.7 pct) were obtained due to fine-grained martensite embedded with nano-sized Nb carbides. The Nb-bearing medium-Mn specimen was successfully warm-stamped into a T-part of a B-pillar prototype at 600 °C without any cracks after austenitized at 750 °C for 5 minutes, and then air-cooled to room temperature. The warm-stamped Nb-bearing medium-Mn steel revealed the higher TE (~ 9.3 pct) than the hot-stamped 30MnB5 steel (5.3 pct) at the similar level of UTS (1855 to 1900 MPa).

AB - The effects of process temperatures for warm stamping, such as annealing (Tann), austenitizing (Taus), and stamping temperatures (Ts), on the tensile properties of Nb-bearing medium-Mn (5.9 wt pct) steel were investigated. The cold-rolled tensile specimens were first annealed at 650 °C to 750 °C, austenitized at 650 °C to 900 °C, held at Ts (500 °C to 700 °C), and then air-cooled to room temperature. Of the three process temperatures, only Taus significantly influenced the tensile properties of medium-Mn steel; in the Taus range of 650 °C to 900 °C, the amount of variation in yield strength (YS), ultimate tensile strength (UTS), and total elongation (TE) were 555 MPa, 570 MPa, and 20 pct, respectively. Particularly, when the specimens were austenitized at 730 °C to 790 °C, high YS (1060 to 1100 MPa), UTS (1760 to 1795 MPa), and TE (10.0 to 11.7 pct) were obtained due to fine-grained martensite embedded with nano-sized Nb carbides. The Nb-bearing medium-Mn specimen was successfully warm-stamped into a T-part of a B-pillar prototype at 600 °C without any cracks after austenitized at 750 °C for 5 minutes, and then air-cooled to room temperature. The warm-stamped Nb-bearing medium-Mn steel revealed the higher TE (~ 9.3 pct) than the hot-stamped 30MnB5 steel (5.3 pct) at the similar level of UTS (1855 to 1900 MPa).

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The Effects of Process Temperatures on the Microstructure and Tensile Properties of Warm-Stamped Nb-Bearing Medium-Mn Steel

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