Details
Original language | English |
---|---|
Pages (from-to) | 4379-4389 |
Number of pages | 11 |
Journal | Journal of Materials Engineering and Performance |
Volume | 29 |
Issue number | 7 |
Publication status | Published - Jul 2020 |
Abstract
The high-strength boron steel 22MnB5 steel is widely used for automotive lightweight constructions. A novel approach is promising to tailor strength and ductility in the hardened condition using locally pre-tempered sheets for the hot stamping process. It results in the formation of locally soft spots where mechanical joining is subsequently intended. A slow pre-cooling of the later joining zones with cooling rates below a certain critical cooling rate for obtaining a decreased strength in these regions is required. A tubular air cooling system suited for this task is presented and tested in a process where the subsequent quenching of the overall sheet is realized by rapid cooling in a water bath. Varying the air pressure and cooling duration allows controlling the size of the softened local spot in a wide range and still obtaining a bainitic microstructure. Using two-stage cooling with point jet nozzles and a subsequent hot stamping process with water-cooled dies resulted in a main sheet hardness of about 470 HV5 and of 260 HV5 in the pre-cooled spots, respectively.
Keywords
- air pre-cooling, press hardening, process-integrated heat treatment
ASJC Scopus subject areas
- Materials Science(all)
- Engineering(all)
- Mechanics of Materials
- Engineering(all)
- Mechanical Engineering
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In: Journal of Materials Engineering and Performance, Vol. 29, No. 7, 07.2020, p. 4379-4389.
Research output: Contribution to journal › Article › Research › peer review
}
TY - JOUR
T1 - Tailoring Soft Local Zones in Quenched Blanks of the Steel 22MnB5 by Partial Pre-cooling with Compressed Air
AU - Golovko, Oleksandr
AU - Stolte, Max Henry
AU - Wölki, Kai
AU - Hübner, Sven
AU - Behrens, Bernd Arno
AU - Maier, Hans Jürgen
AU - Nürnberger, Florian
N1 - Funding information: Open Access funding provided by Projekt DEAL. The presented data were obtained within the project “Production of areas with reduced strength in press-hardened components by means of a tempering station,” Project Number 313453754, granted by the German Research Foundation (DFG). The authors are thankful for the financial support.
PY - 2020/7
Y1 - 2020/7
N2 - The high-strength boron steel 22MnB5 steel is widely used for automotive lightweight constructions. A novel approach is promising to tailor strength and ductility in the hardened condition using locally pre-tempered sheets for the hot stamping process. It results in the formation of locally soft spots where mechanical joining is subsequently intended. A slow pre-cooling of the later joining zones with cooling rates below a certain critical cooling rate for obtaining a decreased strength in these regions is required. A tubular air cooling system suited for this task is presented and tested in a process where the subsequent quenching of the overall sheet is realized by rapid cooling in a water bath. Varying the air pressure and cooling duration allows controlling the size of the softened local spot in a wide range and still obtaining a bainitic microstructure. Using two-stage cooling with point jet nozzles and a subsequent hot stamping process with water-cooled dies resulted in a main sheet hardness of about 470 HV5 and of 260 HV5 in the pre-cooled spots, respectively.
AB - The high-strength boron steel 22MnB5 steel is widely used for automotive lightweight constructions. A novel approach is promising to tailor strength and ductility in the hardened condition using locally pre-tempered sheets for the hot stamping process. It results in the formation of locally soft spots where mechanical joining is subsequently intended. A slow pre-cooling of the later joining zones with cooling rates below a certain critical cooling rate for obtaining a decreased strength in these regions is required. A tubular air cooling system suited for this task is presented and tested in a process where the subsequent quenching of the overall sheet is realized by rapid cooling in a water bath. Varying the air pressure and cooling duration allows controlling the size of the softened local spot in a wide range and still obtaining a bainitic microstructure. Using two-stage cooling with point jet nozzles and a subsequent hot stamping process with water-cooled dies resulted in a main sheet hardness of about 470 HV5 and of 260 HV5 in the pre-cooled spots, respectively.
KW - air pre-cooling
KW - press hardening
KW - process-integrated heat treatment
UR - http://www.scopus.com/inward/record.url?scp=85087341541&partnerID=8YFLogxK
U2 - 10.1007/s11665-020-04916-5
DO - 10.1007/s11665-020-04916-5
M3 - Article
AN - SCOPUS:85087341541
VL - 29
SP - 4379
EP - 4389
JO - Journal of Materials Engineering and Performance
JF - Journal of Materials Engineering and Performance
SN - 1059-9495
IS - 7
ER -