Effect of laser beam wobbling on the overlap joint strength of hot-press-forming steel over 2.0 GPa tensile strength

2022 ◽  
Vol 34 (1) ◽  
pp. 012012
Author(s):  
Kwangsoo Kim ◽  
Namhyun Kang ◽  
Minjung Kang ◽  
Cheolhee Kim
Keyword(s):  
Tensile Strength ◽  
Laser Beam ◽  
Joint Strength ◽  
Hot Press ◽  
Press Forming ◽  
Overlap Joint ◽  
Hot Press Forming

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.

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.

scholarly journals Study on Hot Press Forming Process of Large Curvilinear Generatrix Workpiece of Ti55 High-Temperature Titanium Alloy

Metals ◽  
2018 ◽  
Vol 8 (10) ◽  
pp. 827 ◽  
Author(s):  
Fengyong Wu ◽  
Wenchen Xu ◽  
Zhongze Yang ◽  
Bin Guo ◽  
Debin Shan
Keyword(s):  
Titanium Alloy ◽  
High Temperature ◽  
Fem Simulation ◽  
Alloy Sheet ◽  
Rolled Sheet ◽  
Strain Rates ◽  
Hot Press ◽  
Forming Process ◽  
Press Forming ◽  
Hot Press Forming

In order to manufacture complex curvilinear generatrix workpieces of high-temperature titanium alloy, the hot tensile behavior of Ti55 alloy sheet was tested and the hot press forming process was investigated using Finite Element Method (FEM) simulation and experiment. The hot tensile experiments of Ti55 rolled sheet were conducted at the temperatures of 800–900 °C with the strain rates of 0.001–0.1 s−1. According to the results of hot tensile tests and microstructure evolution, the proper hot press forming parameters were determined as the temperature of 850 °C and the strain rates of 0.001–0.01 s−1. The wrinkling mechanism in the transition region was analyzed and the initial blank sheet geometry was optimized by FE simulation of hot press forming. The two-step hot press forming process was better to produce the complex sheet workpiece of Ti55 alloy than the one-step hot forming scheme, which could restrain the wrinkling trend and ensure the microstructure and mechanical properties of the hot formed workpieces.

Fabrication of Binder-Free Green Composite Using Bamboo Fibers Extracted with a Machining Center

2010 ◽  
Vol 447-448 ◽  
pp. 760-764 ◽  
Author(s):  
Keiji Ogawa ◽  
Toshiki Hirogaki ◽  
Eiichi Aoyama ◽  
Mitsuaki Taniguchi ◽  
Sachiko Ogawa
Keyword(s):  
Present Report ◽  
Bamboo Fiber ◽  
Hot Press ◽  
Green Composite ◽  
Forming Process ◽  
Machining Center ◽  
Press Forming ◽  
Hot Press Forming ◽  
Binder Free ◽  
Bamboo Fibers

Bamboo grows faster than other renewable natural materials. Bamboo fiber, in particular, has attracted attention as an environmentally superior material. Therefore, we proposed a sustainable manufacturing system using bamboo. An extraction method of bamboo fibers end-milled using a machining center with in-situ measurement is proposed. Bamboo fibers with high precision shape are efficiently acquired. In the present report, we propose the fabrication of binder-free composite by a hot press forming method that only uses bamboo fibers extracted by a machining center. We experimentally demonstrated various hot press forming conditions and achieved proper forming conditions to optimize the forming process. We also made various three-dimensional shapes considering the practical applications of the formed binder-free bamboo fiber moldings.

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.

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