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Abstract

The article presents an analysis of stresses in the current tool system of the die during the implementation of the third forging operation of the screw M12 class 10.9 with cylinder head and hexagonal socket. It was assumed that the level of negative cracking due to stress can be reduced by using a mounting interference between the die and the tube blank. Due to the design of the tool system value of the die, the interference value cannot be too large. Therefore, an analysis of the influence of the interference between the die and the tube blank in a die tool system on the value and distribution of stresses in the individual components. An analysis of the assembly stresses and the stresses occurring during the process of deformation of the shaped head of the screw was done. The calculations were performed using a commercial software package MARC / Mentat.

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Authors and Affiliations

I. Nowotyńska
S. Kut
M. Osetek
ORCID: ORCID
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Abstract

The hydrogen embrittlement of metals is caused by the penetration and accumulation of hydrogen atoms inside the metal. The failure of the product due to hydrogen embrittlement is delayed in time and does not occur immediately after its manufacture, but several hours, days, or even weeks later. Therefore, the chances of detecting hydrogen embrittlement when checking the quality of the finished product are very slim. The use of high-strength bolts in industry is associated with the risk of hydrogen embrittlement. This phenomenon poses a threat to the safe use of devices by limiting or completely losing the functionality of the bolt joint. Even a low influence of moisture can trigger failure mechanisms.
The article proposes a method for assessing the risk of hydrogen embrittlement for high-strength bolts in class12.9. For this purpose, bolts made of material grade 32CrB4 were prepared and in a controlled manner the grain flow inconsistency was made, leading in extreme cases to the production of the forging lap. To perform the study, the device proposed by the European Assessment Document (EAD) was adapted to the testing of hydrogen embrittlement of threaded fasteners in concrete. The concrete substrate was replaced with metal spacers that were preloaded with a bolt. The use of the wedge distance under the bolt head led to the generation of two stress states – tensile and compressive, which translated into an increased risk of hydrogen embrittlement. After being tested, the bolts were visually and microscopically inspected to assess potential locations for cracks and hydrogen propagation. As a result of the conducted tests, it was found that the prepared test method allows to assess the resistance or susceptibility of the bolt to threats related to hydrogen embrittlement.
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Authors and Affiliations

T. Dubiel
1
ORCID: ORCID
T. Balawender
2
ORCID: ORCID
M. Osetek
1
ORCID: ORCID

  1. Koelner Rawlplug IP Sp. z o.o. Oddział w Łańcucie, Rzeszów University of Technology
  2. Rzeszów University of Technology, Departament of Materials Forming and Processing, 12 Powstańców Warszawy Av., 35-959 Rzeszów, Poland
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Abstract

The use of cold forging is a widely used solution in many industries. One application is the manufacture of bolts and fasteners. The largest amounts of bolts are used in the automotive and machine industry. Those customers demand high standards of quality and reliability from producers based on ISO 9001 and IATF 16949. Also, the construction, agriculture and furniture industries are raising their expectations for deliveries from year to year.
Automotive companies issue their standards specifying specific requirements for products. One of these standards is the aviation standard SAE USCAR 8-4; 2019, which speaks of a compatible arrangement of fibers in the bolt head and in the area of transition into the mandrel.
The article presents the cold forging process of flange bolts. Obtaining a compatible, acceptable and incompatible grain flow pattern based of the above mantioned standard was presented. Then the results of FEM simulation were correlated with the performed experiment.
The effect of incompatible grain flow system was discussed and presented as the crack initiating factor due to delta ferrite, hydrogen embrittlement, tempering embrittlement. The reliability of the connections was confirmed in the assembly test for yield stress on a Schatz machine. The advantages of this method and the difference compared to the tensile test were presented.
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Bibliography

[1] IA TF 16949: 2016 – Automotive Quality Management System Standard.
[2] ISO 9001: 2015 – Systemy zarządzania jakością – Wymagania.
[3] A. Komornicka, M. Sąsiadek, T. Nahirny, Wyzwania przemysłu motoryzacyjnego w świetle wprowadzania standardów IATF 16949:2016, [in:] R. Knosali, Innowacje w Zarządzaniu i Inżynierii Produkcji, Oficyna Wydawnicza Polskiego Towarzystwa Zarządzania Produkcją.
[4] S. Ziółkiewicz, S. Stachowiak, D. Kaczmarczyk, A. Karpiuk, Obróbka Plastyczna Metali 17 (1), 7-13 (2006).
[5] A. Żmudzki, P. Skubisz, J. Sińczak, M. Pietrzyk, Obróbka Plastyczna Metali 17 (3), 9-19 (2006).
[6] N . Biba, S. Stebounov, A. Lishiny, J. Mater. Process. Tech. 113, 34-39 (2001).
[7] M Saad, S. Akhtar, M. Srivastava, J. Chaurasia, Materials Today: Proceedings 5, 19576-19585 (2018).
[8] A . Dubois, L. Lazzarotto, L. Dubar., J. Oudin, Wear 249, 951-961 (2002).
[9] Y . Nugraha, Theory of WireDrawing, Tirtayasa University (2007).
[10] S.Y. Hsia, Y.T. Chou, J.C. Chao, Advances in Mechanical Engineering 8 (3), 1-10 (2016).
[11] R . Bussoloti, L. Albano, L. de Canale, G.E. Totten, Delta Ferrite: Cracking of Steel Fasteners, [in:] R. Colás, G.E. Totten, Encyclopedia of Iron, Steel, and Their Alloys, Five-Volume Set, CRC Press (2006).
[12] D .H. Herring, Indust Heat 73 (16), 9 (2006).
[13] S.V. Brahimi, S. Yue, K.R. Sriraman, Philos. Trans. A Math. Phys. Eng. Sci. 375 (2098), (2017).
[14] SAE USCAR 8-4;2019 „Grain Flow Pattern for Bolts, Screws and Studs”.
[15] PN -EN 26157-3. Części złączne – Nieciągłości powierzchni – Śruby, wkręty i śruby dwustronne specjalnego stosowania.
[16] ISO 898-1:2013-06 Własności mechaniczne części złącznych wykonanych ze stali węglowej oraz stopowej – Część 1: Śruby i śruby dwustronne o określonych klasach własności – Gwint zwykły i drobnozwojny.
[17] ISO 16047:2007 Części złączne – Badanie zależności moment obrotowy/siła zacisku.
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Authors and Affiliations

T. Dubiel
1
ORCID: ORCID
T. Balawender
2
ORCID: ORCID
M. Osetek
1
ORCID: ORCID

  1. Koelner Rawlplug IP Sp. z o. o. Oddział w Łańcucie / Rzeszów University of Technology, Poland
  2. Rzeszów University of Technology, 12 Powstańców Warszawy Av., 35-959 Rzeszów, Poland

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