Erzeugung duktiler Bereiche beim Formhärten*/Production of ductile areas in hot stamping – Creating areas with reduced strength using a tempering station

2019 ◽  
Vol 109 (10) ◽  
pp. 750-754
Author(s):  
B. Behrens ◽  
S. Hübner ◽  
S. Yarcu ◽  
K. Wölki ◽  
H. Maier ◽  
...  

Formgehärtete Bauteile sind aufgrund ihres Leichtbaupotenzials im Karosseriebau etabliert. Jedoch ist die mechanische und thermische Fügbarkeit aufgrund der hohen Festigkeit stark eingeschränkt. Ein Ansatz zur Verbesserung der Fügeeigenschaften ist die Erzeugung von weichen Fügezonen. Zur gezielten Einstellung von lokal angepassten mechanischen Eigenschaften beim Formhärten wurde daher eine dem Platinenerwärmungsprozess nachgeschaltete Temperierungsstation entwickelt, um Platinen vor dem eigentlichen Formhärten im Hinblick auf eine lokale Entfestigung zu temperieren.   Due to their lightweight, hot-stamped components are established in car body manufacturing. However, high strength limits the application of mechanical and thermal joining operations. One approach to improving the joining properties is the production of ductile joining areas. To achieve locally varying mechanical properties, a tempering station has been developed that is suited to locally adapt the blank temperatures right after the oven process and thus prior to the hot stamping, resulting in tailored mechanical properties after the hot stamping operation.

2013 ◽  
Vol 395-396 ◽  
pp. 909-913 ◽  
Author(s):  
Zi Jian Wang ◽  
Ya Xu ◽  
Wen Ting He ◽  
Yi Sheng Zhang

With the increasingly widespread application of high-strength steel (HSS), tailored properties, namely different mechanical properties required in different regions of the same part, have been proposed, in order to achieve the matching between mechanical properties and safety performance of motor vehicle parts. In this paper, the influence of air gap on the final hardness and strength distribution is discussed in terms of two different HSS, namely LG1500HS and WHT1500HF. As for steel LG1500HS, regardless of the location of samples in the formed part, the final fracture area is in the vicinity of the air gap center, proving the lowest hardness and strength in transition zones. Compared to steel LG1500HS, steel WHT1500HF exhibits gradient hardness distribution from the cooling zone to the heating zone, with no minimal value discovered in transition zones.


2020 ◽  
Vol 4 (4) ◽  
pp. 98 ◽  
Author(s):  
Seong-Woong Choi ◽  
Yong-Seok Kim ◽  
Young-Jin Yum ◽  
Soon-Yong Yang

The post-processing (punching or trimming) of high-strength parts reinforced by hot stamping requires punch molds with improved mechanical properties in hardness, resistance to wear, and toughness. In this study, a semi-additive manufacturing (semi-AM) method of heterogeneous materials was proposed to strengthen these properties using high wear resistance steel (HWS) powder and directed energy deposition (DED) technology. To verify these mechanical properties as a material for the punch mold for cutting, specimens were prepared and tested by a semi-AM method of heterogeneous material. The test results of the HWS additive material by the semi-AM method proposed in this study are as follows: the hardness was 60.59–62.0 HRc, which was like the Bulk D2 specimen. The wear resistance was about 4.2 times compared to that of the D2 specimen; the toughness was about 4.0 times that of the bulk D2 specimen; the compressive strength was about 1.45 times that of the bulk D2 specimen; the true density showed 100% with no porosity. Moreover, the absorption energy was 59.0 J in a multi-semi-AM specimen of heterogeneous materials having an intermediate buffer layer (P21 powder material). The semi-AM method of heterogeneous materials presented in this study could be applied as a method to strengthen the punch mold for cutting. In addition, the multi-semi-AM method of heterogeneous materials will be able to control the mechanical properties of the additive material.


2010 ◽  
Vol 129-131 ◽  
pp. 390-394
Author(s):  
Cheng Xi Lei ◽  
Zhong Wen Xing ◽  
Hong Ya Fu

The numerical simulation of hot-stamping process was carried out for UHSS square-cup parts, and the influence of dies temperature on the hot-stamping process was anlysised. Besides, through the microstructure analysis and mechanical properties testing of the formed parts, effects of dies temperature on microstructures and mechanical properties of hot-stamping square-cup parts were obtained. The experiment and simulation results showed that the mechanical properties of the UHSS are strongly dependent on the temperature, so the dies temperature is one of the most important parameters that have to be taken into account in designing the hot-forming dies and the hot-forming process.


2014 ◽  
Vol 1063 ◽  
pp. 88-92 ◽  
Author(s):  
He Long Cai ◽  
Peng Ju Du ◽  
Hong Liang Yi ◽  
Di Wu

Press hardening steel is the best solution for application of extremely high strength steel in automotive structures in order to reduce the weight of body-in-white. Effect of austenitizing temperature on the grain coarsening of a press hardening steel has been investigated by using dilatometer at first. The mechanical properties of press-hardened steel austenitized at temperature between 850 to 950oC by using a pilot hot stamping line have been investigated. The strength, especially the ultimate tensile strength, was improved by the grain refinement with lower austenitization temperature.


2010 ◽  
Vol 654-656 ◽  
pp. 330-333 ◽  
Author(s):  
Takehide Senuma ◽  
Yoshito Takemoto

Hot stamping is an attractive method to produce extra high strength automotive components. In the conventional hot stamping, the furnace heating is employed and the heating rate is quite low. To improve the productivity of the hot stamping technology, the reduction of time for the heating process is required. In this study, the influence of the heating rate in a range up to 200°C/s, heating temperatures between 650°C and 950°C and cooling condition on microstructure and mechanical properties of 0.22% C -3%Mn steel has been investigated. The steel is a promising material for the highly productive new hot stamping technology because this steel transformed into martensite from austenite even at cooling in free air. The specimens heat-treated at a high heating rate and for short holding time at the heating temperature just above Ac3 show significantly fine martensite microstructure and a good strength-toughness balance. In this paper, the α→ γ transformation behavior and the γ→ α transformation behavior after inter-critical annealing are discussed to explain the evolution of the microstructures and mechanical properties.


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