Microstructural Evolution and Fracture Mechanism for Scar Defect Formation on Advanced High Strength Steel during a Shearing Process

2020 ◽  
pp. 1-22
Author(s):  
Onnjira Diewwanit ◽  
Paranee Keawcha-um ◽  
Thanita Keawcha-um ◽  
Weesuda Petchhan ◽  
Sutasn Thipprakmas
Keyword(s):  
Stress Distribution ◽  
Tensile Test ◽  
Fracture Mechanism ◽  
Defect Formation ◽  
Flow Direction ◽  
High Strength ◽  
Distribution Analysis ◽  
Dp Steel ◽  
Tensile Test Specimen ◽  
Cut Edge

Abstract To form a required shape of the advanced high strength steels especially DP steel sheets, shearing process being one of major processes is commonly used. In general, although the good cut-edge with small fracture could be achieved by setting small shearing clearance, the tearing being a major defect commonly occurred on the cut-edge. Therefore, in the present research, a tearing mechanism on the DP steel sheet, grade SPFC980Y (JIS) during shearing process is investigated and clearly clarified based on the microstructure evolution, fracture mechanism, and stress distribution analysis. The microstructure evolutions on both tensile test specimen and sheared workpiece were performed to clarify the fracture mechanism. The angle between shear band and elongated grain flow direction is examined based on tensile test and it is used to predict an angle of initial fracture and its propagation on the shearing process as well. By associated with stress distribution analysis generated in shearing zone during shearing phase, the results revealed that the fracture propagated out of shearing zone and the fracture could be easily delayed. This resulted in that the tearing could be generated in the case of SPFC980Y. Vice versa, the fracture propagation is all in shearing zone, the fracture could not be delayed and the fracture completely generated on the cut-edge in the case of SPCC. In the present resents, the tearing mechanism on the DP steels in shearing process is clearly characterized.

Stress Distribution Analysis on Four Types of Stress Corrosion Cracking Specimen

2011 ◽  
Vol 462-463 ◽  
pp. 194-199
Author(s):  
Syifaul Huzni ◽  
M. Ridha ◽  
Ahmad Kamal Ariffin
Keyword(s):  
Stress Distribution ◽  
Stress Corrosion ◽  
Stress Corrosion Cracking ◽  
Mesh Size ◽  
Adaptive Mesh ◽  
Corrosion Cracking ◽  
Beam Specimen ◽  
Distribution Analysis ◽  
Potential Measurement ◽  
Tensile Test Specimen

Stress distribution analysis on four types of stress corrosion cracking (SCC) specimen is presented in this paper. This work was performed using commercial finite element based software, ANSYS. Two types of mesh arrangements, fixed mesh with different mesh size and adaptive mesh, were employed in this work to study the effect of mesh size on stress distribution of SCC specimen. Four types of SCC specimen were studied in this work, i.e. C-ring specimen, tensile test specimen, pre-crack cantilever beam specimen and U-bend specimen. Simulation result shows that stress distribution on the SCC specimen much affected by mesh size and arrangement, especially for specimen with notch. By performing the stress analysis, less effort needed in order to determine the location of corrosion potential measurement on the SCC specimen. This will be very helpful for future work of SCC study.

Zn-Assisted Liquid Metal Embrittlement of 980MPa Grade Advanced High Strength Steels

2019 ◽  
Vol 953 ◽  
pp. 3-8
Author(s):  
Ying Hua Jiang ◽  
Jian Zhou ◽  
Can Fu ◽  
Xue Bai
Keyword(s):  
Liquid Metal ◽  
Tensile Test ◽  
High Strength Steels ◽  
High Strength ◽  
Liquid Metal Embrittlement ◽  
Dp Steel ◽  
Structural Part ◽  
Resistance Spot ◽  
Advanced High Strength Steels ◽  
Automotive Body

Recently, the weight reduction of automotive body and crash safety become much more important factors. In addition, the corrosion resistance must be ensured for any material used in a structural part of automotive components. In an effort to satisfy these requirements, zinc-coated high strength steels have been developed. However, challenges to resistance spot weldability of zinc-coated high strength steel such as liquid metal embrittlement (LME) have emerged. In this study, the high temperature tensile test was conducted for 980MPa DP steel. And resistance spot welding was conducted for 980MPa DP steel and CP steel. The results show that the fracture behavior during tensile test are influenced by the temperature and strain rate. Cracks were formed on the weld surface of the DP steel after welding.

scholarly journals Comprehensive Analysis of the Microstructure and Mechanical Properties of Friction-Stir-Welded Low-Carbon High-Strength Steels with Tensile Strengths Ranging from 590 MPa to 1.5 GPa

2021 ◽  
Vol 11 (12) ◽  
pp. 5728
Author(s):  
HyeonJeong You ◽  
Minjung Kang ◽  
Sung Yi ◽  
Soongkeun Hyun ◽  
Cheolhee Kim
Keyword(s):  
Mechanical Properties ◽  
Tensile Test ◽  
Joint Strength ◽  
Solid Phase ◽  
Welding Process ◽  
High Strength Steels ◽  
High Strength ◽  
Low Carbon ◽  
Friction Stir ◽  
Welding Processes

High-strength steels are being increasingly employed in the automotive industry, requiring efficient welding processes. This study analyzed the materials and mechanical properties of high-strength automotive steels with strengths ranging from 590 MPa to 1500 MPa, subjected to friction stir welding (FSW), which is a solid-phase welding process. The high-strength steels were hardened by a high fraction of martensite, and the welds were composed of a recrystallized zone (RZ), a partially recrystallized zone (PRZ), a tempered zone (TZ), and an unaffected base metal (BM). The RZ exhibited a higher hardness than the BM and was fully martensitic when the BM strength was 980 MPa or higher. When the BM strength was 780 MPa or higher, the PRZ and TZ softened owing to tempered martensitic formation and were the fracture locations in the tensile test, whereas BM fracture occurred in the tensile test of the 590 MPa steel weld. The joint strength, determined by the hardness and width of the softened zone, increased and then saturated with an increase in the BM strength. From the results, we can conclude that the thermal history and size of the PRZ and TZ should be controlled to enhance the joint strength of automotive steels.

scholarly journals Porosity Characteristics and Effect on Tensile Shear Strength of High-Strength Galvanized Steel Sheets after the Gas Metal Arc Welding Process

Metals ◽  
2018 ◽  
Vol 8 (12) ◽  
pp. 1077 ◽  
Author(s):  
Seungmin Shin ◽  
Sehun Rhee
Keyword(s):  
Shear Strength ◽  
Arc Welding ◽  
Gas Metal Arc Welding ◽  
Welding Process ◽  
High Strength ◽  
Galvanized Steel ◽  
Tensile Shear Strength ◽  
Tensile Shear ◽  
Tensile Test Specimen ◽  
Metal Arc Welding

In this study, lap joint experiments were conducted using galvanized high-strength steel, SGAFH 590 FB 2.3 mmt, which was applied to automotive chassis components in the gas metal arc welding (GMAW) process. Zinc residues were confirmed using a semi-quantitative energy dispersive X-ray spectroscopy (EDS) analysis of the porosity in the weld. In addition, a tensile shear test was performed to evaluate the weldability. Furthermore, the effect of porosity defects, such as blowholes and pits generated in the weld, on the tensile shear strength was experimentally verified by comparing the porosity at the weld section of the tensile test specimen with that measured through radiographic testing.

The Microstructure and Formability Study on DP Steel of Lightweight Automobile

2011 ◽  
Vol 704-705 ◽  
pp. 1465-1472
Author(s):  
Jin Wu ◽  
Da Sen Bi ◽  
Liang Chu ◽  
Jian Zhang ◽  
Yun Tao Li
Keyword(s):  
Mechanical Property ◽  
Work Hardening ◽  
High Strength Steel ◽  
High Strength ◽  
Mathematic Model ◽  
Theoretical Research ◽  
Forming Limit ◽  
Strain Hardening Exponent ◽  
Dp Steel ◽  
Better Than

Dual phase (DP) steel is a high strength steel for auto-panel. In this paper, mechanical property, forming ability, baked-hardening and work hardening properties of high strength steel DP450 are studied by experiments, and compared with those of steel MS6000.And theoretical research on predicting the forming limit of steel DP450 by the NADDRG model. The established mathematic model for relativity is of practical usefulness. Experimental results reveal that the yield strength of steel DP450 is about 7.2% lower than the MS6000,and the break strength increases by 18.9%,while the elongation increases by 19%.The strain hardening exponent of steel DP450 are superior to those of MS6000.The results show that mechanical property of high strength steel DP450 is better than that of MS6000,while forming ability of DP450 is not lower than that of MS6000.And baked-hardening and work hardening properties of steel DP450 are better than those of MS6000.The steel sheet DP450 owned a good forming ability.

Stress Distribution Analysis of Different Types of Blade for a Fermentation System

2013 ◽  
Vol 479-480 ◽  
pp. 319-323
Author(s):  
Cheng Chi Wang ◽  
Po Jen Cheng ◽  
Kuo Chi Liu
Keyword(s):  
Stress Distribution ◽  
Maximum Stress ◽  
Effective Means ◽  
Materials Processing ◽  
Distribution Analysis ◽  
Stress Distributions ◽  
Fermentation System ◽  
Different Types ◽  
Inclined Angle ◽  
Key Parameter

Fermentation system is widely used for food manufacturing, materials processing and chemical reaction etc. Different types of blade in the tank for fermentation cause distinct stress distributions on the surface between fluid and blade, and appear various flow fields in the tank. So, this paper is mainly focused on analyzing the stress field of blades under different scales of blade with fixing rotational speed. The results show that the ratio of blade length to width influences stress distribution on the blades. At the same time, the inclined angle of blade is also the key parameter for the consideration of design and appropriate design will decrease the maximum stress. The results provide an effective means of gaining insights into the stress distribution of fermentation system.

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