scholarly journals Integrated Machine Vision System for Evaluating Hole Expansion Ratio of Advanced High-Strength Steels

Materials ◽  
2022 ◽  
Vol 15 (2) ◽  
pp. 553
Author(s):  
Jaehoon Park ◽  
Chanhee Won ◽  
Hye-Jin Lee ◽  
Jonghun Yoon
Keyword(s):  
Computer Vision ◽  
Acoustic Emission ◽  
Expansion Ratio ◽  
Integrated Analysis ◽  
Emission Analysis ◽  
Hole Expansion ◽  
Punch Load ◽  
Hole Expansion Ratio ◽  
Load Analysis ◽  
Analysis System

In this paper, we propose a new method to estimate the hole expansion ratio (HER) using an integrated analysis system. To precisely measure the HER, three kinds of analysis methods (computer vision, punch load, and acoustic emission) were utilized to detect edge cracks during a hole expansion test. Cracks can be recognized by employing both computer vision and a punch load analysis system to determine the moment of crack initiation. However, the acoustic emission analysis system has difficulty detecting the instant of crack appearance since the magnitude of the audio signal is drowned out by noise from the press, which interrupts the differentiation of crack configuration. To enhance the accuracy for determining the HER, an integrated analysis system that combines computer vision with punch load analysis, and improves on the shortcomings of each analysis system, is newly suggested.

Prediction of hole expansion ratio for automotive grade steels

2014 ◽  
Vol 89 ◽  
pp. 189-197 ◽  
Author(s):  
Surajit Kumar Paul ◽  
Monideepa Mukherjee ◽  
Saurabh Kundu ◽  
Sanjay Chandra
Keyword(s):  
Expansion Ratio ◽  
Hole Expansion ◽  
Hole Expansion Ratio

The Study in Improvement of Hole Expansibility for High-Strength Steel of 980MPa Grade

2018 ◽  
Vol 941 ◽  
pp. 492-497
Author(s):  
Kuo Cheng Yang ◽  
J.F. Tu ◽  
L.J. Chiang ◽  
W.J. Cheng ◽  
C.Y. Huang
Keyword(s):  
Yield Strength ◽  
High Strength Steel ◽  
Dual Phase Steel ◽  
Single Phase ◽  
High Strength ◽  
Expansion Ratio ◽  
High Yield ◽  
Dual Phase ◽  
Hole Expansion ◽  
Hole Expansion Ratio

Recently, due to the requirements of lightweight and safety, the grade of 980MPa high-strength steel has the demand of high hole expansibility and high yield strength. Due to the large difference of hardness between the soft ferrite and hard martensite, the traditional DP980Y dual phase steel has poor hole expansibility. In order to improve the hole expansibility of DP980Y dual phase steel, the best way is to modify the microstructure into a single-phase to eliminate the large difference of hardness. In this paper, the steel of nearly full bainite microstructure with small amount of ferrite and M/A constituents was studied. Compared to the DP980Y dual phase steel, it was found that this modified steel with a single-phase microstructure has the same grade of 980MPa of tensile strength, but can achieve the demand of higher yield strength and hole-expansion ratio. This study shows reducing the amount of ferrite can increase the homogeneity of matrix with the single phase to improve the hole expansibility. In addition, the use of lower bainite transformation temperature and lower carbon content has the higher hole-expansion ratio due to the less amount of M/A constituents.

Improving Hole Expansion Ratio by Parameter Adjustment in Abrasive Water Jet Operations for DP800

2018 ◽  
Vol 11 (3) ◽  
pp. 241-252
Author(s):  
Bernd-Arno Behrens ◽  
David Diaz-Infante ◽  
Taylan Altan ◽  
Deniz Yilkiran ◽  
Kai Wölki ◽  
...  
Keyword(s):  
Expansion Ratio ◽  
Water Jet ◽  
Abrasive Water Jet ◽  
Parameter Adjustment ◽  
Hole Expansion ◽  
Hole Expansion Ratio

scholarly journals Effects of Piercing Punch Coating on Hole-expansion Ratio and Fatigue Properties

2015 ◽  
Vol 56 (649) ◽  
pp. 133-138
Author(s):  
Takashi MATSUNO ◽  
Koichi SATO ◽  
Akihiro UENISHI ◽  
Shigeki HIGUCHI ◽  
Tetsuya MASUDA ◽  
...  
Keyword(s):  
Expansion Ratio ◽  
Fatigue Properties ◽  
Hole Expansion ◽  
Hole Expansion Ratio

Improvement in Punching Properties of High Tensile Strength Steel Sheet by Heat-Treatments for Reduction of Center Segregation

2014 ◽  
Vol 622-623 ◽  
pp. 1075-1080 ◽  
Author(s):  
Kota Sakumoto ◽  
Kazuhiko Yamazaki ◽  
Takashi Kobayashi ◽  
Shinsuke Suzuki
Keyword(s):  
Heat Treatment ◽  
Tensile Strength ◽  
Crack Formation ◽  
Expansion Ratio ◽  
High Tensile Strength ◽  
Burr Height ◽  
Hole Expansion ◽  
Steel Sheets ◽  
Heat Treated ◽  
Hole Expansion Ratio

We investigated punching properties (crack in punched surface and hole expansion ratio) of high tensile strength steel sheets with and without center segregation. High strength steel sheets were heat-treated to reduce center segregation. Tensile strength, shear surface ratio, depth of rollover and burr height were measured on heat-treated steel sheets to confirm the effect of heat-treatment on strength. The EPMA analysis showed that the center segregation of Mn was reduced by the diffusion during heat-treatment. Crack-formation frequency and hole expansion ratio were also measured. As a result, the center segregation of Mn in high tensile strength steel sheets decreased by the heat-treatment (600 oC for 100 h) with maintaining the tensile strength, the depth of rollover and the burr height. The crack-formation frequency of the steel sheets decreased through heat-treatments.

Fundamental aspect of stretch-flangeability of sheet metals

2018 ◽  
Vol 233 (10) ◽  
pp. 2115-2119 ◽  
Author(s):  
Surajit Kumar Paul
Keyword(s):  
Tensile Test ◽  
Sheet Metal ◽  
Expansion Ratio ◽  
Uniaxial Tensile ◽  
Uniaxial Tensile Test ◽  
Hole Expansion ◽  
Expansion Test ◽  
Localized Necking ◽  
Hole Expansion Test ◽  
Hole Expansion Ratio

Stretch-flangeability of sheet metal is normally represented by hole expansion ratio. Hole expansion ratio cannot be determined from uniaxial tensile test though uniaxial tensile deformation occurs at the hole’s edge, because of fundamental difference in deformation and damage processes present between hole expansion test and uniaxial tensile test. It is proposed that only localized necking is observed in hole expansion test; however, diffuse necking followed by localized necking is observed in uniaxial tensile test of sheet metal. It is noticed that the hole expansion ratio is marginally higher than maximum diffuse neck strain determined from uniaxial tensile test with local strain measurement by digital image correlation technique. The absence of diffuse neck in hole expansion test with defect-free central hole (i.e. electrical discharge machined hole) results far higher hole expansion ratio than uniform elongation of the material.

Factors governing hole expansion ratio of steel sheets with smooth sheared edge

2016 ◽  
Vol 22 (6) ◽  
pp. 1009-1014 ◽  
Author(s):  
Jae Ik Yoon ◽  
Jaimyun Jung ◽  
Hak Hyeon Lee ◽  
Gyo-Sung Kim ◽  
Hyoung Seop Kim
Keyword(s):  
Expansion Ratio ◽  
Hole Expansion ◽  
Steel Sheets ◽  
Sheared Edge ◽  
Hole Expansion Ratio
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