scholarly journals Mechanical Properties Of Laser Welded Dual-Phase Steel Joints

2021 ◽  
Author(s):  
Naheen Farabi
Keyword(s):  
Mechanical Properties ◽  
Heat Treatment ◽  
Automobile Industry ◽  
Fatigue Properties ◽  
Dual Phase ◽  
Soft Zone ◽  
Ductile Mode ◽  
Negative Effect ◽  
Hardness Increase ◽  
Steel Joints

The application of dual phase (DP) steels in the automobile industry unavoidably involves welding operation. The objective of this thesis was to study the microstructure and mechanical properties of laser welded DP steel joints. The laser welding resulted in a significant hardness increase in the FZ but the formation of a soft zone in the heat affected zone (HAZ). While the soft zone influenced the tensile properties of the joints considerably, the fatigue properties of the welds showed dependence on both the softening and the applied stress amplitudes. Fatigue crack was observed to initiate from the specimen surface and crack propagation was basically characterized by striation-like features. Post-weld heat treatment was found to eradicate the negative effect of the soft zone and improve the mechanical properties of welds. However, the heat treatment resulted in a brittle fracture mode from the dominating ductile mode of fracture of the welded joints.

scholarly journals Mechanical Properties Of Laser Welded Dual-Phase Steel Joints

2021 ◽  
Author(s):  
Naheen Farabi
Keyword(s):  
Mechanical Properties ◽  
Heat Treatment ◽  
Automobile Industry ◽  
Fatigue Properties ◽  
Dual Phase ◽  
Soft Zone ◽  
Ductile Mode ◽  
Negative Effect ◽  
Hardness Increase ◽  
Steel Joints

The application of dual phase (DP) steels in the automobile industry unavoidably involves welding operation. The objective of this thesis was to study the microstructure and mechanical properties of laser welded DP steel joints. The laser welding resulted in a significant hardness increase in the FZ but the formation of a soft zone in the heat affected zone (HAZ). While the soft zone influenced the tensile properties of the joints considerably, the fatigue properties of the welds showed dependence on both the softening and the applied stress amplitudes. Fatigue crack was observed to initiate from the specimen surface and crack propagation was basically characterized by striation-like features. Post-weld heat treatment was found to eradicate the negative effect of the soft zone and improve the mechanical properties of welds. However, the heat treatment resulted in a brittle fracture mode from the dominating ductile mode of fracture of the welded joints.

Effects of cooling rate on the mechanical properties of dual phase treated vanadium steels

1983 ◽  
Vol 41 ◽  
pp. 220-221
Author(s):  
L.J. Chen ◽  
H.C. Cheng ◽  
J.R. Gong ◽  
J.G. Yang
Keyword(s):  
Mechanical Properties ◽  
Cooling Rate ◽  
Automobile Industry ◽  
High Strength ◽  
Weight Percent ◽  
Low Alloy Steels ◽  
Dual Phase ◽  
Resource Requirement ◽  
Alloy Steels ◽  
Potential Weight

For fuel savings as well as energy and resource requirement, high strength low alloy steels (HSLA) are of particular interest to automobile industry because of the potential weight reduction which can be achieved by using thinner section of these steels to carry the same load and thus to improve the fuel mileage. Dual phase treatment has been utilized to obtain superior strength and ductility combinations compared to the HSLA of identical composition. Recently, cooling rate following heat treatment was found to be important to the tensile properties of the dual phase steels. In this paper, we report the results of the investigation of cooling rate on the microstructures and mechanical properties of several vanadium HSLA steels.The steels with composition (in weight percent) listed below were supplied by China Steel Corporation: 1. low V steel (0.11C, 0.65Si, 1.63Mn, 0.015P, 0.008S, 0.084Aℓ, 0.004V), 2. 0.059V steel (0.13C, 0.62S1, 1.59Mn, 0.012P, 0.008S, 0.065Aℓ, 0.059V), 3. 0.10V steel (0.11C, 0.58Si, 1.58Mn, 0.017P, 0.008S, 0.068Aℓ, 0.10V).

scholarly journals Grain Size Evolution and Mechanical Properties of Nb, V–Nb, and Ti–Nb Boron Type S1100QL Steels

Metals ◽  
2021 ◽  
Vol 11 (3) ◽  
pp. 492
Author(s):  
Jan Foder ◽  
Jaka Burja ◽  
Grega Klančnik
Keyword(s):  
Mechanical Properties ◽  
Heat Treatment ◽  
Grain Size ◽  
Hot Forging ◽  
Size Control ◽  
High Strength ◽  
Fatigue Properties ◽  
Titanium Addition ◽  
Austenite Grain Size ◽  
Size Evolution

Titanium additions are often used for boron factor and primary austenite grain size control in boron high- and ultra-high-strength alloys. Due to the risk of formation of coarse TiN during solidification the addition of titanium is limited in respect to nitrogen. The risk of coarse nitrides working as non-metallic inclusions formed in the last solidification front can degrade fatigue properties and weldability of the final product. In the presented study three microalloying systems with minor additions were tested, two without any titanium addition, to evaluate grain size evolution and mechanical properties with pre-defined as-cast, hot forging, hot rolling, and off-line heat-treatment strategy to meet demands for S1100QL steel. Microstructure evolution from hot-forged to final martensitic microstructure was observed, continuous cooling transformation diagrams of non-deformed austenite were constructed for off-line heat treatment, and the mechanical properties of Nb and V–Nb were compared to Ti–Nb microalloying system with a limited titanium addition. Using the parameters in the laboratory environment all three micro-alloying systems can provide needed mechanical properties, especially the Ti–Nb system can be successfully replaced with V–Nb having the highest response in tensile properties and still obtaining satisfying toughness of 27 J at –40 °C using Charpy V-notch samples.

scholarly journals Relationships among the Microstructure, Mechanical Properties, and Fatigue Behavior in Thin Ti6Al4V

2016 ◽  
Vol 2016 ◽  
pp. 1-9 ◽  
Author(s):  
Y. Fan ◽  
W. Tian ◽  
Y. Guo ◽  
Z. Sun ◽  
J. Xu
Keyword(s):  
Mechanical Properties ◽  
Heat Treatment ◽  
Fatigue Strength ◽  
Laser Welding ◽  
Fracture Strength ◽  
Fatigue Behavior ◽  
Fatigue Properties ◽  
Proof Stress ◽  
Martensite Microstructure

The microstructures of Ti6Al4V are complex and strongly affect its mechanical properties and fatigue behavior. This paper investigates the role of microstructure on mechanical and fatigue properties of thin-section Ti6Al4V sheets, with the aim of reviewing the effects of microstructure on fatigue properties where suboptimal microstructures might result following heat treatment of assemblies that may not be suited to further annealing, for example, following laser welding. Samples of Ti6Al4V sheet were subjected to a range of heat treatments, including annealing and water quenching from temperatures ranging from 650°C to 1050°C. Micrographs of these samples were inspected for microstructure, and hardness, 0.2% proof stress, elongation, and fracture strength were measured and attributed back to microstructure. Fractography was used to support the findings from microstructure and mechanical analyses. The strength ranking from high to low for the microstructures of thin Ti6Al4V sheets observed in this study is as follows: acicularα′martensite, Widmanstätten, bimodal, and equiaxed microstructure. The fatigue strength ranking from high to low is as follows: equiaxed, bimodal, Widmanstätten, and acicularα′martensite microstructure.

Microstructure and Fatigue Properties of Laser Welded DP590 Dual-Phase Steel Joints

2017 ◽  
Vol 26 (8) ◽  
pp. 3794-3801 ◽  
Author(s):  
Chaojie Xie ◽  
Shanglei Yang ◽  
Haobo Liu ◽  
Qi Zhang ◽  
Yaming Cao ◽  
...  
Keyword(s):  
Dual Phase Steel ◽  
Fatigue Properties ◽  
Dual Phase ◽  
Steel Joints

Heat Treatment Recycling of Dual Phase Region and its Effect on Hardness, Microstructure and Corrosion Rate of Medium Carbon Steel

2014 ◽  
Vol 909 ◽  
pp. 100-104
Author(s):  
Mohamed A. Gebril ◽  
M.S. Aldlemey ◽  
Farag I. Haider
Keyword(s):  
Heat Treatment ◽  
Carbon Steel ◽  
Corrosion Rate ◽  
Phase Region ◽  
Medium Carbon Steel ◽  
Dual Phase ◽  
Two Phase ◽  
Medium Carbon ◽  
The Third ◽  
Hardness Increase

In this work, the investigations were carried out to study the effect of heat treatment at dual phase of austenite and ferrite on mechanical properties , microstructure and corrosion rate of low alloyed medium carbon steel. The specimens were divided into five groups, first group, specimens were heated to the duel phase region at temperature of 740°C soaked for 30 minutes and quenched in water. The second group, The specimens were heated to 740°C soaked for 30 minutes and quenched in water, then tempered to 480°C soaked for 20 minutes. The third group the specimens were heated to austenizing temperature of 840°C soaked for 30 minutes and quenched in water, then the specimens reheated to the dual phase region at 740°C, soaked for 30 minutes and quenched in water, then the specimens were tempered at temperature 480°C for 30 minutes. The forth group, the specimens were heated to austenizing temperature of 840°C soaked for 30 minutes and quenched in water, this process were repeated again before the specimens were thereafter heated to the dual phase region at temperature of 740°C, soaked for 20 minutes and quenched in water, then the specimens were tempered at temperature 480°C for 20 minutes. The fifth group, the specimens were heated to austenizing temperature of 840°C soaked for 20 minutes and quenched in water, this process were repeated two times again before the specimens were thereafter heated to the dual phase region at temperature of 740°C, soaked for 20 minutes and quenched in water, then the specimens finally tempered at temperature 480°C for 20 minutes. The results proved the hardness increase after heat treatment at first and second group, at third group the highest hardness value was due to formation of martensite and ferrite, but at fourth and fifth groups hardness decreases due to appearance of carbides particles, also corrosion rate usually increases with two phase at microstructure than stable one phase, third group have less corrosion rate than fourth and fifth due to carbides particles formation which lead to more corrosion rate due to three phases presents.

scholarly journals Fatigue properties of laser welded dual-phase steel joints

2010 ◽  
Vol 2 (1) ◽  
pp. 835-843 ◽  
Author(s):  
N. Farabi ◽  
D.L. Chen ◽  
Y. Zhou
Keyword(s):  
Dual Phase Steel ◽  
Fatigue Properties ◽  
Dual Phase ◽  
Steel Joints
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