Forming a Flanged Hole When Quenching Press-Hardened Steel for Mechanical Fastening

The recent stringent regulations on vehicle safety and reducing CO<sub>2</sub> emissions have led to a continuous increase in the application of press-hardened steel (PHS) in automobiles. Similar to other high-strength steels, assembling PHS components using the common welding techniques...

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Main Authors: Yongjun Jeon, Hyunseok Choi, Dongearn Kim
Format: Article
Language:English
Published: MDPI AG 2021-04-01
Series:Metals
Subjects:
Online Access:https://www.mdpi.com/2075-4701/11/5/721
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author Yongjun Jeon
Hyunseok Choi
Dongearn Kim
author_facet Yongjun Jeon
Hyunseok Choi
Dongearn Kim
author_sort Yongjun Jeon
collection DOAJ
description The recent stringent regulations on vehicle safety and reducing CO<sub>2</sub> emissions have led to a continuous increase in the application of press-hardened steel (PHS) in automobiles. Similar to other high-strength steels, assembling PHS components using the common welding techniques employed in automotive production lines is significantly difficult because of the surface coating layers and the additives within. This difficulty in post-processing, attributed to its high strength, also limits the mechanical fastening of PHS components. Therefore, this study aims to develop a process for forming a structure enabling mechanical fastening by sequentially applying piercing and hole-flanging operations during the hot stamping process. Our experimental apparatus was designed to perform the hole-flanging operation after the piercing operation within a single stroke at a specific temperature during the quenching process of PHS. At high temperatures of 440 °C or higher, the hole-flanging process was conducted in a direction opposite to that of the piercing operation for creating the pilot hole. An extruded collar with a height of 8.0 mm and a diameter of 17.5 mm was achieved, which is hole expansion ratio(HER) of 82.5%.
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spelling doaj.art-38d00728377f4d3395528b0045e696462023-11-21T17:29:36ZengMDPI AGMetals2075-47012021-04-0111572110.3390/met11050721Forming a Flanged Hole When Quenching Press-Hardened Steel for Mechanical FasteningYongjun Jeon0Hyunseok Choi1Dongearn Kim2Shape Manufacturing R&D Department, Korea Institute of Industrial Technology, Incheon 21999, KoreaSchool of Mechanical Engineering, Korea University, Seoul 02841, KoreaShape Manufacturing R&D Department, Korea Institute of Industrial Technology, Incheon 21999, KoreaThe recent stringent regulations on vehicle safety and reducing CO<sub>2</sub> emissions have led to a continuous increase in the application of press-hardened steel (PHS) in automobiles. Similar to other high-strength steels, assembling PHS components using the common welding techniques employed in automotive production lines is significantly difficult because of the surface coating layers and the additives within. This difficulty in post-processing, attributed to its high strength, also limits the mechanical fastening of PHS components. Therefore, this study aims to develop a process for forming a structure enabling mechanical fastening by sequentially applying piercing and hole-flanging operations during the hot stamping process. Our experimental apparatus was designed to perform the hole-flanging operation after the piercing operation within a single stroke at a specific temperature during the quenching process of PHS. At high temperatures of 440 °C or higher, the hole-flanging process was conducted in a direction opposite to that of the piercing operation for creating the pilot hole. An extruded collar with a height of 8.0 mm and a diameter of 17.5 mm was achieved, which is hole expansion ratio(HER) of 82.5%.https://www.mdpi.com/2075-4701/11/5/721press-hardened steelhole-flangingwarm piercinghole expansion ratiomechanical fastening
spellingShingle Yongjun Jeon
Hyunseok Choi
Dongearn Kim
Forming a Flanged Hole When Quenching Press-Hardened Steel for Mechanical Fastening
Metals
press-hardened steel
hole-flanging
warm piercing
hole expansion ratio
mechanical fastening
title Forming a Flanged Hole When Quenching Press-Hardened Steel for Mechanical Fastening
title_full Forming a Flanged Hole When Quenching Press-Hardened Steel for Mechanical Fastening
title_fullStr Forming a Flanged Hole When Quenching Press-Hardened Steel for Mechanical Fastening
title_full_unstemmed Forming a Flanged Hole When Quenching Press-Hardened Steel for Mechanical Fastening
title_short Forming a Flanged Hole When Quenching Press-Hardened Steel for Mechanical Fastening
title_sort forming a flanged hole when quenching press hardened steel for mechanical fastening
topic press-hardened steel
hole-flanging
warm piercing
hole expansion ratio
mechanical fastening
url https://www.mdpi.com/2075-4701/11/5/721
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AT hyunseokchoi formingaflangedholewhenquenchingpresshardenedsteelformechanicalfastening
AT dongearnkim formingaflangedholewhenquenchingpresshardenedsteelformechanicalfastening