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.

scholarly journals Influence of Ti and Nb on the Strength–Ductility–Hole Expansion Ratio Balance of Hot-rolled Low-carbon High-strength Steel Sheets

2012 ◽  
Vol 52 (1) ◽  
pp. 151-157 ◽  
Author(s):  
Kyohei Kamibayashi ◽  
Yutaka Tanabe ◽  
Yoshito Takemoto ◽  
Ichirou Shimizu ◽  
Takehide Senuma
Keyword(s):  
High Strength Steel ◽  
High Strength ◽  
Expansion Ratio ◽  
Low Carbon ◽  
Hole Expansion ◽  
Steel Sheets ◽  
Hole Expansion Ratio ◽  
Hot Rolled

scholarly journals Hole Expansion Ratio and Fatigue Properties in Piercing of High-Strength Steel Sheets by PW Punch

2011 ◽  
Vol 52 (606) ◽  
pp. 795-800 ◽  
Author(s):  
Takashi MATSUNO ◽  
Yukihisa KURIYAMA ◽  
Hiroya MURAKAMI ◽  
Shota YONEZAWA ◽  
Naonobu KANAMARU
Keyword(s):  
High Strength Steel ◽  
High Strength ◽  
Expansion Ratio ◽  
Fatigue Properties ◽  
Hole Expansion ◽  
Steel Sheets ◽  
Hole Expansion Ratio

Increasing the Hole Expansion Ability of High Strength Steel Sheet by Improving the Pre-Hole Shearing Process

2019 ◽  
Vol 962 ◽  
pp. 167-174
Author(s):  
Prasan Saengkhiao ◽  
Komgrit Lawanwong ◽  
Pakorn Chumrum
Keyword(s):  
High Strength Steel ◽  
Steel Sheet ◽  
High Strength ◽  
Expansion Ratio ◽  
Expansion Process ◽  
Forming Process ◽  
Research Papers ◽  
Hole Expansion ◽  
Hole Edge ◽  
Hole Expansion Ratio

The hole expansion process is a forming process that the fracture easily occurred on the hole edge. Therefore, many research papers presented various processes to make a precision pre-hole shearing to a hole expansion process such as wire cut, EDM, and laser cut. The purpose of this work is to increase a hole expansion ratio on the high strength steel sheet. The conventional piercing by piercing punch and piercing with a counter punch was used to make a pre-hole shearing process in this research paper. The high strength steel grade 590 and 980 MPa of 1.2 mm of thickness were used in the experiments. From experimental results, it was found that the pre-hole shearing by piercing with a counter punch can be increased a shear surface on cutting edge of workpiece. Moreover, the used piercing with counter punch can improve the hole expansion ratio more than the conventional piercing process because sheared surface around the hole edge was increased.

Forming Performance of 800MPa Grade Advanced High Strength Steels

2013 ◽  
Vol 455 ◽  
pp. 173-178 ◽  
Author(s):  
Mei Zhang ◽  
Yu Xiang Ning ◽  
Jun Zhang ◽  
Zi Wan ◽  
Tao Wang
Keyword(s):  
High Strength Steels ◽  
High Strength ◽  
Expansion Ratio ◽  
Hole Expansion ◽  
Advanced High Strength Steels ◽  
Hsla Steels ◽  
Blank Holding Force ◽  
Hole Expansion Ratio ◽  
Test Hole ◽  
Springback Behavior

800MPa grade Advanced High Strength Steels (AHSS), including Complex Phase steel CP800 and Ferrite-Bainite steel FB800, were chosen to test the forming performance in different test conditions and compared with the reference traditional high strength low alloy (HSLA) steels HR700LA. Tensile test, hole expansion (HE) test, and HAT shape stamping test were taken to investigate the forming performance of the materials. Test results indicated that the studied 800MPa grade AHSS showed a better strength ductility balance compared with the reference steel. Among all the steels researched, FB800 showed the best hole expansion ratio (HER), and CP800 the worst. Springback angles of AHSS after HAT shape stamping tests were markedly smaller than those of HR700LA steels, though the springback angles of HR700LA decreased continuously with blank holding force (BHF) increasing. Steel FB800, CP800S and CP800B had much better shape stability compared with steels HR700LA. AHSS showed much smaller springback behavior under the same stamping condition, especially for steels CP800-B, FB800-2 and FB800-1. When increasing the BHF to 100KN, AHSS showed the largest springback deformation. Among the three kinds of CP800 steels researched, steel CP800-B indicated outstanding springback restrain trend in BHF further increasing attempt. So, springback behavior could be restricted obviously by using a larger BHF in AHSS CP800B forming operations.

USS DUAL PHASE 80

Alloy Digest ◽  
1978 ◽  
Vol 27 (12) ◽  
Keyword(s):  
United States ◽  
Corrosion Resistance ◽  
Yield Strength ◽  
Work Hardening ◽  
Steel Sheet ◽  
High Strength ◽  
Heat Treating ◽  
Dual Phase ◽  
United States Steel Corporation ◽  
Heavy Construction

Abstract USS Dual Phase 80 is a high-strength steel sheet which has a dual phase structure of martensite and ferrite. It provides all the benefits of higher strength with little sacrifice in ductility, formability or weldability. Dual Phase 80 gains strength as it is formed through rapid work hardening of its unique microstructure; in fact, it increases from its delivered yield strength of 50,000 psi up to 80,000 psi (or more) in forming. Its final strength depends on the amount of forming. Its many applications include automotive vehicles, farm equipment and heavy construction equipment. This datasheet provides information on composition, hardness, and tensile properties. It also includes information on corrosion resistance as well as forming, heat treating, machining, and joining. Filing Code: SA-352. Producer or source: United States Steel Corporation.

REPUBLIC 50

Alloy Digest ◽  
1967 ◽  
Vol 16 (1) ◽  
Keyword(s):  
Fracture Toughness ◽  
Corrosion Resistance ◽  
Yield Strength ◽  
Physical Properties ◽  
Structural Steel ◽  
High Strength ◽  
Heat Treating ◽  
High Yield ◽  
Bend Strength ◽  
High Yield Strength

Abstract Republic 50 is a high-strength low-alloy structural steel recommended where high yield strength and toughness combined with good weldability and corrosion resistance are required. This datasheet provides information on composition, physical properties, elasticity, tensile properties, and compressive, shear, and bend strength as well as fracture toughness and fatigue. It also includes information on corrosion resistance as well as forming, heat treating, machining, and joining. Filing Code: SA-205. Producer or source: Republic Steel Corporation.

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