Predictions of the Mechanical Properties and Microstructure Evolution of High Strength Steel in Hot Stamping

Abstract High strength steel products with good ductility can be produced via Q&P hot stamping process, while the phase transformation of the process is more complicated than common hot stamping since two-step quenching and one-step carbon partitioning processes are involved. In this study, an integrated model of microstructure evolution relating to Q&P hot stamping was presented with a persuasively predicted results of mechanical properties. The transformation of diffusional phase and non-diffusional phase, including original austenite grain size individually, were considered, as well as the carbon partitioning process which affects the secondary martensite transformation temperature and the subsequent phase transformations. Afterwards, the mechanical properties including hardness, strength, and elongation were calculated through a series of theoretical and empirical models in accordance with phase contents. Especially, a modified elongation prediction model was generated ultimately with higher accuracy than the existed Mileiko’s model. In the end, the unified model was applied to simulate the Q&P hot stamping process of a U-cup part based on the finite element software LS-DYNA, where the calculated outputs were coincident with the measured consequences.

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Effects of Hot Trimming Conditions on Sheared-edge Quality and Mechanical Properties in Hot Stamping of Ultra-high Strength Steel Parts

Journal of the Japan Society for Technology of Plasticity ◽

10.9773/sosei.59.221 ◽

2018 ◽

Vol 59 (694) ◽

pp. 221-227

Author(s):

Yuki NAKAGAWA ◽

Ken-ichiro MORI ◽

Tomoyoshi MAENO ◽

Ryo UMEMIYA

Keyword(s):

Mechanical Properties ◽

High Strength Steel ◽

Hot Stamping ◽

High Strength ◽

Sheared Edge ◽

Ultra High Strength Steel ◽

Edge Quality

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Mechanical Properties and Microstructure of High-Strength Steel Controlled by Hot Stamping Process

Journal of Materials Engineering and Performance ◽

10.1007/s11665-018-3290-1 ◽

2018 ◽

Vol 27 (8) ◽

pp. 4025-4035 ◽

Cited By ~ 1

Author(s):

Hang Ou ◽

Xu Zhang ◽

Junrui Xu ◽

Guangyao Li ◽

Junjia Cui

Keyword(s):

Mechanical Properties ◽

High Strength Steel ◽

Hot Stamping ◽

High Strength ◽

Stamping Process

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Hot Stamping of Two Different High Strength Steel with Tailored Properties

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.395-396.909 ◽

2013 ◽

Vol 395-396 ◽

pp. 909-913 ◽

Cited By ~ 6

Author(s):

Zi Jian Wang ◽

Ya Xu ◽

Wen Ting He ◽

Yi Sheng Zhang

Keyword(s):

Mechanical Properties ◽

High Strength Steel ◽

Motor Vehicle ◽

Hot Stamping ◽

High Strength ◽

Air Gap ◽

Heating Zone ◽

Cooling Zone ◽

Widespread Application ◽

Transition Zones

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.

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