Application of self-piercing nuts during hot forming of 22MNB5

authored by: Sebastian Meyer, Gerson Meschut, Hendrik Vogt, Bernd Arno Behrens, Sven Hübner, André Neumann
Abstract: The increasing use of hot-formed steels for structural components in lightweight construction requires solutions to create mounting points into the thin blank of high-strength steel. Compared to welding nuts, self-piercing nuts are often used due to advantages for the mechanical properties. The problems of setting these elements in hot-formed steels like 22MnB5 are high process forces and often limited undercuts, which are produced during the joining process. In this regard, the application of the self-piercing nut during the hot forming process of 22MnB5 is the focus of the investigation. The particular challenge is to find out the desired process parameter in a defined temperature window. Thus, the ductile austenitized 22MnB5 is exploited, while the local shape of the deformed blank in contact with the self-piercing nut is realized. A newly developed process enables insertion of the self-piercing nuts by different joining conditions. In order to evaluate the efficiency of the new process, various aspects are recorded. To achieve a successful hot forming process by a complete martensitic microstructure transformation, a minimum cooling rate of 27 K/s is provided. Furthermore, it has to be assured, that there is no thermal influence on the nut element, while the blank and the self-piercing nut are strongly heated. Otherwise, this can lead to a change in the strength class of the nut. For this purpose, hardness measurement is used to analyze the microstructure development. The mechanical behavior is described by torsion- and pull-out tests.
Organisation(s): Institute of Metal Forming and Metal Forming Machines
External Organisation(s): Paderborn University
Type: Article
Journal: Welding in the world
Volume: 63
Pages: 565-574
No. of pages: 10
ISSN: 0043-2288
Publication date: 08.03.2019
Publication status: Published
Peer reviewed: Yes
ASJC Scopus subject areas: Mechanics of Materials, Mechanical Engineering, Metals and Alloys
Electronic version(s): https://doi.org/10.1007/s40194-018-00688-8 (Access: Closed)
: Details in the research portal "Research@Leibniz University"

BibTeX

@article{dbd627adcea5427699b175c0ced61e60,
title = "Application of self-piercing nuts during hot forming of 22MNB5",
abstract = "The increasing use of hot-formed steels for structural components in lightweight construction requires solutions to create mounting points into the thin blank of high-strength steel. Compared to welding nuts, self-piercing nuts are often used due to advantages for the mechanical properties. The problems of setting these elements in hot-formed steels like 22MnB5 are high process forces and often limited undercuts, which are produced during the joining process. In this regard, the application of the self-piercing nut during the hot forming process of 22MnB5 is the focus of the investigation. The particular challenge is to find out the desired process parameter in a defined temperature window. Thus, the ductile austenitized 22MnB5 is exploited, while the local shape of the deformed blank in contact with the self-piercing nut is realized. A newly developed process enables insertion of the self-piercing nuts by different joining conditions. In order to evaluate the efficiency of the new process, various aspects are recorded. To achieve a successful hot forming process by a complete martensitic microstructure transformation, a minimum cooling rate of 27 K/s is provided. Furthermore, it has to be assured, that there is no thermal influence on the nut element, while the blank and the self-piercing nut are strongly heated. Otherwise, this can lead to a change in the strength class of the nut. For this purpose, hardness measurement is used to analyze the microstructure development. The mechanical behavior is described by torsion- and pull-out tests.",
keywords = "22MnB5, Hot forming, Mechanical joining, Self-piercing nuts",
author = "Sebastian Meyer and Gerson Meschut and Hendrik Vogt and Behrens, {Bernd Arno} and Sven H{\"u}bner and Andr{\'e} Neumann",
year = "2019",
month = mar,
day = "8",
doi = "10.1007/s40194-018-00688-8",
language = "English",
volume = "63",
pages = "565--574",
journal = "Welding in the world",
issn = "0043-2288",
publisher = "Springer Verlag",
number = "2",
}