scholarly journals Evolution of Phase Transition and Mechanical Properties of Ultra-High Strength Hot-Stamped Steel During Quenching Process

Metals ◽  
2020 ◽  
Vol 10 (1) ◽  
pp. 138 ◽  
Author(s):  
Shuang Liu ◽  
Mujun Long ◽  
Songyuan Ai ◽  
Yan Zhao ◽  
Dengfu Chen ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Phase Transition ◽  
Cooling Rate ◽  
Hot Stamping ◽  
Coupled Model ◽  
High Strength ◽  
Austenitizing Temperature ◽  
Stamping Process ◽  
Quenching Process ◽  
Hot Stamping Steel

Hot stamping process is widely used in the manufacture of the high strength automotive steel, mainly including the stamping and quenching process of the hot-formed steel. In the hot stamping process, the steel is heated above the critical austenitizing temperature, and then it is rapidly stamped in the mold and the quenching phase transition occurs at the same time. The quenching operation in the hot stamping process has a significant influence on the phase transition and mechanical properties of the hot-stamping steel. A proper quenching technique is quite important to control the microstructure and properties of an ultra-high strength hot-stamping steel. In this paper, considering the factors of the austenitizing temperature, the austenitizing time and the cooling rate, a coupled model on the thermal homogenization and phase transition from austenite to martensite in quenching process was established for production of ultra-high strength hot-stamping steel. The temperature variation, the austenite decomposition and martensite formation during quenching process was simulated. At the same time, the microstructure and the properties of the ultra-high strength hot-stamping steel after quenching at different austenitizing temperature were experimental studied. The results show that under the conditions of low cooling rate, the final quenching microstructure of the ultra-high strength hot-stamping steel includes martensite, residual austenite, bainite and ferrite. With the increase of the cooling rate, bainite and ferrite gradually disappear. While austenitizing at 930 °C, the tensile strength, yield strength, elongation and strength-ductility product of the hot-stamping steel are 1770.1 MPa, 1128.2 MPa, 6.72% and 11.9 GPa%, respectively.

scholarly journals Study on Phase Transformation in Hot Stamping Process of USIBOR® 1500 High-Strength Steel

Metals ◽  
2019 ◽  
Vol 9 (10) ◽  
pp. 1119 ◽  
Author(s):  
Pengyun Zhang ◽  
Le Zhu ◽  
Chenyang Xi ◽  
Junting Luo
Keyword(s):  
Phase Transformation ◽  
High Strength Steel ◽  
Hot Stamping ◽  
High Strength ◽  
Transformation Kinetics ◽  
Martensite Content ◽  
Cct Curve ◽  
Stamping Process ◽  
Quenching Process ◽  
Kinetics Of

Based on the Kirkaldy-Venugopalan model, a theoretical model for the phase transformation of USIBOR® 1500 high strength steel was established, and a graph of the phase transformation kinetics of ferrite, pearlite, and bainite were plotted using the software MATLAB. Meanwhile, with the use of the software DYNAFORM, the thermal stamping process of an automobile collision avoidance beam was simulated. The phase transformation law of USIBOR® 1500 high-strength steel during hot stamping was studied through a simulation of the phase transformation during the pressure holding quenching process. In combination with the continuous cooling transformation (CCT) curve, the cooling rate of quenching must be greater than 27 °C/s to ensure maximum martensite content in the final parts, and the final martensite content increases as the initial temperature of the sheet rises.

Effect of Dies Temperature on Mechanical Properties of Hot Stamping Square-Cup Part for Ultra High Strength Steel

2010 ◽  
Vol 129-131 ◽  
pp. 390-394
Author(s):  
Cheng Xi Lei ◽  
Zhong Wen Xing ◽  
Hong Ya Fu
Keyword(s):  
Mechanical Properties ◽  
Numerical Simulation ◽  
Hot Stamping ◽  
High Strength ◽  
Hot Forming ◽  
Forming Process ◽  
Stamping Process ◽  
Ultra High Strength Steel ◽  
Mechanical Properties Testing ◽  
Simulation Results

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.

Effects of Austenitizing Temperature on Microstructure and Properties of Hot-Formed Steel

2014 ◽  
Vol 1063 ◽  
pp. 88-92 ◽  
Author(s):  
He Long Cai ◽  
Peng Ju Du ◽  
Hong Liang Yi ◽  
Di Wu
Keyword(s):  
Mechanical Properties ◽  
Hot Stamping ◽  
High Strength ◽  
Hardened Steel ◽  
Austenitizing Temperature ◽  
Austenitization Temperature ◽  
Press Hardening ◽  
Automotive Structures ◽  
Body In White ◽  
Press Hardening Steel

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.

Localized Austenitizing of the Blank to Make Tailored-Properties by Induction Heating

2014 ◽  
Vol 1063 ◽  
pp. 190-193
Author(s):  
Pei Xing Liu ◽  
Hong Liang Yi ◽  
Ya Xu ◽  
Yi Lin Wang ◽  
Yi Sheng Zhang
Keyword(s):  
Temperature Field ◽  
Ambient Temperature ◽  
Induction Heating ◽  
Thermal Conduction ◽  
Hot Stamping ◽  
High Strength ◽  
Mold Design ◽  
Austenitizing Temperature ◽  
Stamping Process ◽  
Local Areas

In this research, a novel hot stamping process to make tailored-properties is proposed. The local areas of blank are heated by induction heating. In the high strength zones, they are heated to austenitizing temperature, and in the absorption zones without heating. The temperature field of transition zone is determined by the thermal conduction between austenitizing temperature and ambient temperature. This novel process can be used for industrialization without changing mold design and stamping process.

FE-Simulation of the Heat Transfer by Defined Cooling Conditions during the Hot Stamping Process

2011 ◽  
Vol 473 ◽  
pp. 699-706 ◽  
Author(s):  
Thomas Svec ◽  
Martin Grüner ◽  
Marion Merklein
Keyword(s):  
Heat Transfer ◽  
Mechanical Properties ◽  
Hot Stamping ◽  
High Strength Steels ◽  
High Strength ◽  
Process Data ◽  
Cold Forming ◽  
Stamping Process ◽  
Characteristic Values ◽  
Tempering Process

Increasing demands regarding security aspects and light weight construction lead to the application of advanced high strength steels (AHSS) and ultra high strength steels (UHSS) in the automotive sector. Due to high process forces and the reduced formability of these steel grades within cold forming new manufacturing technologies like the hot stamping process are required. Furthermore, crash-performance plays an important role in the automotive industry. Therefore functional optimized components are necessary. Hence, actual research work within the community is focused on manufacturing components with local adjusted mechanical properties. One of the strategies to realize the contradictorily requirements regarding energy absorption and structural integrity is the Tailored tempering process where the cooling rates are adjusted by controlled heating or cooling of different tool zones within the hot stamping process. Thereby knowledge concerning the influence of the different heated tool parts on the heat transfer and the resulting mechanical properties is necessary. Furthermore, the applicability and the accuracy of the calculation approaches used for characteristic values like the heat transfer coefficient in the FE-based simulation have to be analyzed and evaluated. Due to this experiments with a tool which exhibits a heated and a cooled zone were performed according to the Tailored tempering process. During the experiments contact pressures and tool temperatures in the heated tool part were varied and analyzed regarding the influence on the heat transfer. Furthermore, the heat transfer coefficients were calculated and verified by a numerical model built according to the experimental setup and the accuracy of the model was evaluated by the comparison of characteristic values calculated from the experimental and numerical process data.

scholarly journals Study on the prediction of tensile strength and phase transition for ultra-high strength hot stamping steel

2020 ◽  
Vol 9 (6) ◽  
pp. 14244-14253
Author(s):  
Shuang Liu ◽  
Mujun Long ◽  
Siyuan Zhang ◽  
Yan Zhao ◽  
Jingjun Zhao ◽  
...  
Keyword(s):  
Phase Transition ◽  
Tensile Strength ◽  
Hot Stamping ◽  
High Strength ◽  
Hot Stamping Steel

Effect of Pre-Heating Temperature on Microstructure and Properties of 22MnB5 Steel Hot Stamping

2014 ◽  
Vol 1063 ◽  
pp. 108-111
Author(s):  
Ping Li ◽  
Yu Sheng Liu ◽  
Tian Zong Gongzi ◽  
Ke Min Xue
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Martensitic Transformation ◽  
Heating Temperature ◽  
Hot Stamping ◽  
High Strength ◽  
High Tensile Strength ◽  
22Mnb5 Steel ◽  
Stamping Process ◽  
Ultra High Strength Steel

The hot stamping process of ultra high strength steel(UHSS) sheet is an innovative way to manufacture the components with a ultra high tensile strength. The sufficiency of martensitic transformation in formed component is affected by pre-heating temperature of blank directly. In this paper, experiments of heating UHSS blanks to 700°C, 800°C, 900°C and 1000°C were implemented to investigate the effect of pre-heating temperature on the formed component’s microstructure and mechanical properties. The results indicate that 900°C is the best pre-heating temperature for hot stamping process. The microstructure of formed component is all fine and uniform martensite. Meanwhile, tensile strength and vickers hardness raise up to 1580MPa and 450HV, respectively.

scholarly journals Integrated Modelling of Microstructure Evolution and Mechanical Properties Prediction for Q&P Hot Stamping Process of Ultra-High Strength Steel

2020 ◽  
Vol 33 (1) ◽  
Author(s):  
Yang Chen ◽  
Huizhen Zhang ◽  
Johnston Jackie Tang ◽  
Xianhong Han ◽  
Zhenshan Cui
Keyword(s):  
Mechanical Properties ◽  
Microstructure Evolution ◽  
High Strength Steel ◽  
Hot Stamping ◽  
High Strength ◽  
Carbon Partitioning ◽  
Integrated Modelling ◽  
Finite Element Software ◽  
Stamping Process ◽  
Mechanical Properties Prediction

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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