Tools and Technologies for Hot Forming with Local Adjustment of Part Properties

2010 ◽  
Vol 638-642 ◽  
pp. 3919-3924 ◽  
Author(s):  
Ralf Kolleck ◽  
Robert Veit

In general hot stamped car body parts show a uniform strength distribution. Especially for safety relevant parts with high requirements concerning crash performance, this uniform strength distribution can cause problems. During a crash a B-pillar e. g. can absorb more energy when the lower part is relatively flexible while the middle and upper part has to be high-tensile to prevent the intrusion into the passenger compartment. Also during the production of hot stamped parts, the high strength causes trouble. When the trimming takes place after the hardening process, the durability of the tool is limited. Thus at the moment the only economic process for trimming of ultra-high-strength steels is laser cutting. This paper presents different approaches to reach local different strength distributions in hot stamped components. In particular the results of a research project of the Institute Tools & Forming, Graz University of Technology are shown where precisely defined areas of different strengths could be obtained in one part. This was achieved by the use of simple and cheap ceramic inserts in conventional press hardening tools.

2019 ◽  
Vol 25 (2) ◽  
pp. 101 ◽  
Author(s):  
Hana Jirková ◽  
Kateřina Opatová ◽  
Štěpán Jeníček ◽  
Jiří Vrtáček ◽  
Ludmila Kučerová ◽  
...  

<p class="AMSmaintext">Development of high strength or even ultra-high strength steels is mainly driven by the automotive industry which strives to reduce the weight of individual parts, fuel consumption, and CO<sub>2</sub> emissions. Another important factor is to improve passenger safety. In order to achieve the required mechanical properties, it is necessary to use suitable heat treatment in addition to an appropriate alloying strategy. The main problem of these types of treatments is the isothermal holding step. For TRIP steels, the holding temperature lies in the field of bainitic transformation. These isothermal holds are economically demanding to perform in industrial conditions. Therefore new treatments without isothermal holds, which are possible to integrate directly into the production process, are searched. One way to produce high-strength sheet is the press-hardening technology. Physical simulation based on data from a real-world press-hardening process was tested on CMnSi TRIP steel. Mixed martensitic-bainitic structures with ferrite and retained austenite (RA) were obtained, having tensile strengths in excess of 1000 MPa.</p>


2016 ◽  
Author(s):  
Joseba Mendiguren ◽  
Rafael Ortubay ◽  
Xabier Agirretxe ◽  
Lander Galdos ◽  
Eneko Sáenz de Argandoña

2018 ◽  
Vol 941 ◽  
pp. 317-322 ◽  
Author(s):  
Hana Jirková ◽  
Kateřina Opatová ◽  
Josef Káňa ◽  
Dagmar Bublíková ◽  
Martin Bystrianský

Development of high strength or even ultra-high strength steels is mainly driven by the automotive industry which strives to reduce the weight of individual parts, fuel consumption, and CO2 emissions. Another important factor is the passenger safety which will improve by the use of these materials. In order to achieve the required mechanical properties, it is necessary to use suitable heat treatment in addition to an appropriate alloying strategy. The main problem of these treatments is the isothermal holding time. These holding times are technologically demanding which is why industry seeks new possibilities to integrate new processing methods directly into the production process. One option for making high-strength sheet metals is press-hardening which delivers high dimensional accuracy and a small spring-back effect. In order to test the use of AHSS steels for this technology, a material-technological modelling was chosen. Material-technological models based on data obtained directly from a real press-hardening process were examined on two experimental steels, CMnSi TRIP and 42SiCr. Variants with isothermal holding and continuous cooling profiles were tested. It was found that by integrating the Q&P process (quenching and partitioning) into press hardening, the 42SiCr steel can develop strengths of over 1800 MPa with a total elongation of about 10%. The CMnSi TRIP steel with lower carbon content and without chromium achieved a tensile strength of 1160 MPa with a total elongation of 10%.


2013 ◽  
Vol 549 ◽  
pp. 133-140
Author(s):  
Werner Homberg ◽  
Tim Rostek

nnovative ultra high-strength steels have excellent mechanical properties which commonly relate to the materials martensitic microstructure. As thermal heat treatments are state-of-the-art for obtaining the desired microstructure, innovative thermo-mechanical treatments are likely to give rise to even better material qualities. This article highlights various aspects of innovative thermo-mechanical hardening strategies for the processing of ultra high-strength steels, involving both press hardening and friction spinning operations.


2021 ◽  
Vol 174 ◽  
pp. 111035
Author(s):  
Ajit Kumar Pramanick ◽  
Hrishikesh Das ◽  
Ji-Woo Lee ◽  
Yeyoung Jung ◽  
Hoon-Hwe Cho ◽  
...  

2014 ◽  
Vol 775-776 ◽  
pp. 136-140 ◽  
Author(s):  
Renato Araujo Barros ◽  
Antonio Jorge Abdalla ◽  
Humberto Lopes Rodrigues ◽  
Marcelo dos Santos Pereira

The 4340 are classified as ultra-high strength steels used by the aviation industry and aerospace applications such as aircraft landing gear and several structural applications, usually in quenched and tempered condition. In this situation occurs reduction of toughness, which encourages the study of multiphasic and bainític structures, in order to maintain strength without loss of toughness. In this study, ferritic-pearlitic structure was compared to bainitic and martensitic structure, identified by the reagents Nital, LePera and Sodium Metabisulfite. Sliding wear tests of the type pin-on-disk were realized and the results related to the microstructure of these materials and also to their hardnesses. It is noted that these different microstructures had very similar behavior, concluding that all three tested pairs can be used according to the request level.


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