Effect of Process Parameters in Hot Press Forming Operation to Tensile Strength of Ultra High Strength Steel

2014 ◽  
Vol 974 ◽  
pp. 179-182
Author(s):  
Mohd Zairulnizam Zawawi ◽  
Nik Mohd Hafiz Aiman Nik Haron
Keyword(s):  
Tensile Strength ◽  
Cooling Rate ◽  
High Strength ◽  
Cooling Time ◽  
Boron Steel ◽  
Air Cooling ◽  
Hot Press ◽  
Press Forming ◽  
Steel Material ◽  
Hot Press Forming

The escalating issues on sustainable environment such as the necessity to reduce CO2 emission and fuel consumption including new regulations to improve the safety of passengers car had brought up the application of new innovative materials and manufacturing process in the automotive industry called hot press forming operation. By using this new technique, the manufacturers can produce more lightweight and high strength car parts such as the B-pillars with tensile strength ranging from 1200MPa to 1600MPa. Hot press forming is done by rapidly heating up Ultra High Strength Steels (UHSS) made of boron steel material in a furnace to austenization temperature of about 950°C for 5 minutes, then transferred it quickly to the hot press die where rapid quenching occurred during the die closed with the aid of cooling channel. This experiment investigates the effects of varying combination of hot press forming parameters to final tensile strength of boron steel and had been carried out without use of cooling channel. The studied parameters are the air cooling time, cooling rate, cooling time in die and stamping pressure. The type of boron steel material with trade name of Usibor® 1500 was used as the test specimens while for punch and die material, High Thermal Conductivity Tool Steel (HTCS-150) made by Rovalma was used. Both are common materials used in the automotive industry for hot press forming operation. A preliminary experiment had been conducted where ten flat tensile strength specimens of Usibor 1500 were heated to the austenization temperature of 950°C and immediately quenched in a tank of water to confirm the material ability to achieve the minimum tensile strength of 1500MPa. All specimens achieved average tensile strength of 1550MPa in this most ideal cooling rate condition. In the experimental hot press forming operation, result shows that the flat blank specimens of Usibor 1500 able to obtain ultimate tensile strength of 1400MPa after quenching in die without use of cooling channels when suitable process parameters were used during. Overall ,faster air cooling time, higher stamping pressure applied to the blank, and longer cooling time in die improve the cooling rate. Highest tensile strength of 1400MPa was achieved in the experiment when cooling rate was 95°C/s, air cooling time of 3.83s, stamping pressure of 50bar and cooling time in die of 30s.

Simulation of Thermal Distortion in Hot Press Forming with Dissimilar Material TWB

2014 ◽  
Vol 1063 ◽  
pp. 330-333
Author(s):  
Hyun Ho Bok ◽  
Jong Won Choi ◽  
Myoung Gyu Lee ◽  
Frédéric Barlat ◽  
Dong Jin Kim
Keyword(s):  
Shape Change ◽  
Element Model ◽  
Boron Steel ◽  
Air Cooling ◽  
Thermal Distortion ◽  
Hot Press ◽  
Steel Sheets ◽  
Press Forming ◽  
Hot Press Forming ◽  
Micro Alloyed Steel

In order to predict the shape change in hot press forming of a TWB made with HPF1470 boron steel and HSLA340 micro-alloyed steel sheets, a coupled thermo-mechanical-metallurgical finite element model was developed to simulate the process. The simulation consisted of air cooling, forming, die-quenching and, finally, by a treatment designed to relax residual stresses. It is shown in this paper that the experimentally observed distortion in the TWB part was reasonably captured by the simulations.

The Effect of Cooling Rate on Mechanical Properties of 22MnB5 Steel Sheet during Hot Press Forming

2011 ◽  
Vol 264-265 ◽  
pp. 241-247 ◽  
Author(s):  
Ki Young Kwon ◽  
Nak Hyun Kim ◽  
Chung Gil Kang
Keyword(s):  
Mechanical Properties ◽  
Steel Sheet ◽  
Cooling Water ◽  
High Strength Steels ◽  
High Strength ◽  
Hydraulic Press ◽  
Boron Steel ◽  
Hot Press ◽  
Press Forming ◽  
Hot Press Forming

There has been a growing usage of high strength steels (HSS), particularly in automobile applications mainly as structural parts in view of their light weight and high strength properties. These materials are also being considered for dynamic applications. However, the multi-phase microstructure, which is at the base of the strengthening mechanisms in most of these steels, leads to unacceptably high stresses during forming and significant springback phenomena, thus making traditional sheet metal forming technologies unsuitable. To avoid the disadvantages, a new process method was introduced – Hot Press Forming. Hot press forming (HPF) process is a forming method which can provide various advantages such as excellent mechanical properties and formability, good weldability and little springback. Here, the experiment parameters which include locations of the cooling holes and the flow rate of the cooling water play an important role in the HPF process. In this paper, the Al-Si coated boron steel sheet was researched by heating it up to 930oC for 5 min and formed by a hydraulic press. In this study, microstructural evolutions and the associated mechanical properties were investigated in terms of the flow rates of the cooling water.

Mechanical Characterization Behavior of Boron Steel Sheet in Hot Press Forming Process with Cooling System

2011 ◽  
Vol 264-265 ◽  
pp. 48-53
Author(s):  
S.H. An ◽  
Ki Young Kwon ◽  
Chung Gil Kang
Keyword(s):  
Heat Transfer ◽  
Cooling Rate ◽  
Material Properties ◽  
Cooling System ◽  
Boron Steel ◽  
Hot Press ◽  
Forming Process ◽  
Press Forming ◽  
Hot Press Forming ◽  
The Heat Transfer Coefficient

When cooling a boron sheet that has been heated to over 900 °C by hot press forming (HPF) process, the microstructure obtains a martensitic structure by controlling the cooling rate. HPF has advantages such as improvement in formability and material properties, and minimal springback of the formed material. The facts influenced by the cooling rate are determined by the heat transfer characteristics between the heated materials and the dies. In this study, controlling of the cooling rate is addressed by controlling the heat transfer coefficient of the material during the pressing process. This study demonstrates the material properties and microstructures of the formed material during the HPF process wherein cold dies are used to form the heated steel plate. This is achieved by varying the major forming conditions: the cooling rates, which is regarded as the most important process parameter.

scholarly journals Effect of initial blank temperature in hot press forming towards 22MnB5 springback failure

2019 ◽  
Vol 13 (2) ◽  
pp. 5137-5149
Author(s):  
C. H. Ng ◽  
C. F. Lai ◽  
S. N. M. Yahaya ◽  
S. Shamsudin ◽  
S. N. A. S. Ahmad ◽  
...  
Keyword(s):  
High Strength ◽  
Boron Steel ◽  
Hot Press ◽  
Forming Process ◽  
Quenching Rate ◽  
Press Forming ◽  
Initial Blank ◽  
Hot Press Forming ◽  
Formed Part ◽  
The Impact

The springback failure of ultra-high strength boron steel (22MnB5) in hot press forming (HPF) process was characterized under bending and membrane conditions. Hot press forming for U–shaped parts with ultra-high strength boron steel were experimented and simulated to study the effect of initial blank temperatures on springback failure in the automotive industry. The results specify the various preheated temperature of 22MnB5 blank effect toward springback occurrences with reference to hot press forming dies design. ANSYS Workbench was used to verify finite element (FE) simulations of the processes in order to consolidate the knowledge of springback. The validated numerical simulation model were used in analyzing the stress and strain distributions along the formed part in the FE models, it was found that the springback angle was related in averaging value throughout quenching, regardless of the forming conditions. Springback failure mainly caused dimension deviation in hot press form parts due to the impact of thermal restoring moments and quenching rate of hot press forming process.

scholarly journals Microstructure and Mechanical Properties of Laser Welded Al-Si Coated Hot-Press-Forming Steel Joints

Materials ◽  
2019 ◽  
Vol 12 (20) ◽  
pp. 3294 ◽  
Author(s):  
Xi Chen ◽  
Zhenglong Lei ◽  
Yanbin Chen ◽  
Meng Jiang ◽  
Ze Tian ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Laser Power ◽  
Welding Process ◽  
High Strength ◽  
Hot Press ◽  
Press Forming ◽  
Hot Press Forming ◽  
Steel Joints ◽  
Qualification Rate

High strength steel has attracted a lot of attention due to its excellent advantage of weight reduction. A thin Al-Si coating covered on the surface of hot-press-forming (HPF) steel offers functions of antioxidation and decarburization under high temperature processing conditions. In this study, the microstructure characteristic, phase, microhardness, and tensile strength of laser welded Al-Si coated HPF steel joints were investigated at different laser powers. Experimental results show that the welding process becomes unstable because of metallic vapor generated by ablation of the coating. Some of the white bright rippled Fe-Al phase was observed to be distributed in the fusion zone randomly. It is found that microhardness, tensile strength, and cupping test qualification rate decreases with the increase of the laser power. For the 1.1 kW laser power, the sound weld performs the best mechanical properties: Microhardness of 466.53 HV and tensile strength of 1349.9 MPa.

Experimental Assessment of High Temperature Formability of Boron Steel Sheet Manufactured With a Spring Compound Bending Die

2012 ◽  
Vol 134 (2) ◽  
Author(s):  
Yang Li ◽  
Yong-Phil Jeon ◽  
Chung-Gil Kang
Keyword(s):  
Mechanical Properties ◽  
Heating Temperature ◽  
Boron Steel ◽  
Hot Press ◽  
Forming Process ◽  
Steel Sheets ◽  
Press Forming ◽  
Bending Process ◽  
Tension Testing ◽  
Hot Press Forming

Bending behavior occurs in the hot press forming process, resulting in many cases of failure during forming. To address the problem of cracking and improve the formability and mechanical properties of boron steel sheets in the bending process, an experiment has been carried out by using a spring compound bending die. Also, a comparison has been made between the traditional U-bending die and the spring compound bending die with regard to formability. The influence of the parameters for hot press forming such as the heating temperature, punch speed, and die radii on the mechanical properties and microstructure was analyzed by tension testing and metallographic observations.

Hardness Prediction of Tailor Rolled Blank in Hot Press Forming Using Quench Factor Analysis

2017 ◽  
Vol 729 ◽  
pp. 110-114
Author(s):  
Jae Hong Kim ◽  
Dae Cheol Ko ◽  
Byung Min Kim
Keyword(s):  
Factor Analysis ◽  
Fe Simulation ◽  
Boron Steel ◽  
Rear Side ◽  
Cooling Curves ◽  
Hot Press ◽  
Tailor Rolled Blank ◽  
Side Member ◽  
Press Forming ◽  
Hot Press Forming

This paper aims to predict the hardness of hot formed part for tailor rolled blank (TRB) by the FE-simulation coupled with quenching factor analysis (QFA). Dilatometry test of boron steel is performed at various range of cooling rates from 0.2 to 100°C/s using the dilatometer with forced air cooling system. The dilatometry test provides a hardness data according to cooling curves which are used to determine the material constants (K1~K5) of QFA and the time‒temperature‒property (TTP) diagram of boron steel. Then, FE‒simulation of hot press forming is conducted to predict the cooling curves of hot formed TRB part with a thickness combination of thicker 1.6mm and thinner 1.2mm which is called as rear side member of automotive component. The cooling curves of FE-simulation are applied to predict the hardness of hot formed rear side member using the QFA. Also, experiment of hot press forming is performed to verify the predicted results and to examine the effect of cooling curves on the hardness.

Flow characteristics of aluminum coated boron steel in hot press forming

2009 ◽  
Vol 19 (4) ◽  
pp. 913-916 ◽  
Author(s):  
Jeong-Hwan JANG ◽  
Jae-Ho LEE ◽  
Byeong-Don JOO ◽  
Young-Hoon MOON
Keyword(s):  
Flow Characteristics ◽  
Boron Steel ◽  
Hot Press ◽  
Press Forming ◽  
Hot Press Forming

Ultra-high strength and excellent ductility in multi-layer steel sheet of austenitic hadfield and martensitic hot-press-forming steels

2019 ◽  
Vol 759 ◽  
pp. 320-328 ◽  
Author(s):  
Jaeyeong Park ◽  
Min Cheol Jo ◽  
Taejin Song ◽  
Hyoung Seop Kim ◽  
Seok Su Sohn ◽  
...  
Keyword(s):  
Steel Sheet ◽  
High Strength ◽  
Hot Press ◽  
Press Forming ◽  
Hot Press Forming ◽  
Layer Steel
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