scholarly journals Effect of Bainite to Ferrite Yield Strength Ratio on the Deformability of Mesostructures for Ferrite/Bainite Dual-Phase Steels

Materials ◽  
2021 ◽  
Vol 14 (18) ◽  
pp. 5352
Author(s):  
Gui-Ying Qiao ◽  
Zhong-Tao Zhao ◽  
Xian-Bo Shi ◽  
Yi-Yin Shan ◽  
Gu Yu ◽  
...  
Keyword(s):  
Tensile Strength ◽  
Yield Strength ◽  
Strain Hardening ◽  
Pipeline Steel ◽  
Strain Hardening Exponent ◽  
Strength Increase ◽  
Dual Phase ◽  
Strength Ratio ◽  
Soft Phase ◽  
Deformation Compatibility

The strength and plasticity balance of F/B dual-phase X80 pipeline steels strongly depends on deformation compatibility between the soft phase of ferrite and the hard phase of bainite; thus, the tensile strength of ferrite and bainite, as non-negligible factors affecting the deformation compatibility, should be considered first. In this purely theoretical paper, an abstract representative volume elements (RVE) model was developed, based on the mesostructure of an F/B dual-phase X80 pipeline steel. The effect of the yield strength difference between bainite and ferrite on tensile properties and the strain hardening behaviors of the mesostructure was studied. The results show that deformation first occurs in ferrite, and strain and stress localize in ferrite prior to bainite. In the modified Crussard-Jaoul (C-J) analysis, as the yield strength ratio of bainite to ferrite (σy,B/σy,F) increases, the transition strain associated with the deformation transformation from ferrite soft phase deformation to uniform deformation of ferrite and bainite increases. Meanwhile, as the uncoordinated deformation of ferrite and bainite is enhanced, the strain localization factor (SLF) increases, especially the local strain concentration. Consequently, the yield, tensile strength, and yield ratio (yield strength/tensile strength) increase with the increase in σy,B/σy,F. Inversely, the strain hardening exponent and uniform elongation decrease.

Influence of Volume Fraction of Bainite on Mechanical Properties of X80 Pipeline Steel with Excellent Deformability

2011 ◽  
Vol 695 ◽  
pp. 271-274
Author(s):  
Xiao Yong Zhang ◽  
Hui Lin Gao ◽  
Xue Qin Zhang ◽  
Yan Yang
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Yield Strength ◽  
Volume Fraction ◽  
Pipeline Steel ◽  
Dual Phase ◽  
Absorption Energy ◽  
Impact Absorption Energy ◽  
Impact Absorption ◽  
Work Hardening Exponent

The pipeline steel with excellent deformability with ferrite and bainite dual-phase microstructure are obtained by inter-critically accelerating cooling method, aiming to get good deformation capability of avoiding failure from the geological disasters such as landslides and earthquake. The influence of volume fraction of bainite on the mechanical properties of dual-phase pipeline steels was investigated by means of microscopic analysis method and mechanical properties testing. The results indicated that both yield strength and ultimate tensile strength of the steels increase almost linearly with the increasing volume fraction of bainite, while ductility, work hardening exponent and impact absorption energy decrease. When the volume fraction of bainite is about 50%, the yield strength, the yield strength/tensile strength ratio (Y/T), work hardening exponent, uniform elongation and impact absorption energy of X80 pipeline steels with excellent deformability is 665MPa, 0.8, 0.12, 8% and 245J respectively.

Effects of Low-Angle Grain Boundaries on the Yield-Strength Ratio of High Grade Pipeline Steels

2010 ◽  
Vol 168-170 ◽  
pp. 1581-1585 ◽  
Author(s):  
Dong Ying Xu ◽  
Hao Yu
Keyword(s):  
Grain Size ◽  
Tensile Strength ◽  
Yield Strength ◽  
Grain Boundaries ◽  
Pipeline Steel ◽  
High Grade ◽  
Strength Ratio ◽  
Pipeline Steels ◽  
Effective Grain Size ◽  
Electron Back Scattered Diffraction

Orientations distribution between grains of two high grade pipeline steels were investigated by electron back-scattered diffraction (EBSD). Then the percentage of low-angle grain boundaries was studied qualitatively to analyze the effect of low-angle grain boundaries on the yield-strength ratio of high grade pipeline steels. From the mode of coordinate deformation and the ability to resist deformation by the grain boundaries, the results show that when the effective grain size are almost the same, the pipeline steel which has the smaller percentage of low-angle grain boundaries, the larger difference between the yield strength and tensile strength, which makes the yield-strength ratio of pipeline steel lower.

Study on the Variation of the Properties with Increasing of Bending Cycles of Coiled Tubing

2010 ◽  
Vol 146-147 ◽  
pp. 1369-1374
Author(s):  
Zong Yue Bi ◽  
Lin Yun Xian ◽  
Xiao Tian Jing
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Yield Strength ◽  
Strain Hardening ◽  
Strain Hardening Exponent ◽  
Cycle Fatigue ◽  
Coiled Tubing ◽  
The One ◽  
Changing Tendency

The Variation of the mechanical properties of coiled tubing with increasing of the bending cycles was studied based on the fatigue bending cycle machine. The results show that the tensile strength had no significance changes during cycle fatigue. The yield strength and the force value was significantly decreased after 300 cycles, and the corresponding decreased magnitude linearly increased with the increasing of bending cycles. The changing tendency of strain hardening exponent on compression surface is different from the one on extruded surface. When the cycles increase from 100 to 600, the exponent on compression surface shows increases firstly, and decreases afterwards, However, the one on extruded surface shows decreases firstly, and increases afterwards. The yield strengths of the compression surface and extruded surface show the same changing tendency as strain hardening exponent.

Evaluation and Characterization of ASS316L at Sub-Zero Temperature

2019 ◽  
Author(s):  
Satyanarayana Kosaraju ◽  
Anil Kalluri ◽  
Swadesh Kumar Singh ◽  
Ahsan ul Haq
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Stainless Steel ◽  
Austenitic Stainless Steel ◽  
Ultimate Tensile Strength ◽  
Yield Strength ◽  
Strain Hardening ◽  
Process Parameters ◽  
Salt Water ◽  
Strain Hardening Exponent

Abstract Austenitic Stainless-Steel grade 316L is one among the significant ASS grades which is most commonly used in various industry sectors. It has excellent corrosion resistance in ordinary atmospheric and also in more arduous environments such as salt water and environments where resistance to chloride corrosion is required. Whilst performing well when exposed to relatively high temperatures, this grade of Austenitic Stainless steel also maintains its strength and toughness at sub-zero temperatures, making this an excellent choice for various applications in industries sectors such as Marine, general construction, and water treatment. Therefore, present study focused on evaluating the mechanical properties such as ultimate tensile strength (UTS), yield strength (YS) and strain hardening exponent (n) are evaluated based on the experimental data obtained from the uniaxial isothermal tensile tests performed at an interval of −25 °C from 0 °C to −50 °C and at three orientations (0, 45, 90) degrees to the rolling direction and cross head velocity (3, 5, 7) mm/min were chosen. A total of 27 experiments have been planned based on design of experiments to conduct experiments. A mathematical model for the prediction of ultimate tensile strength (UTS), yield strength (YS) and strain hardening exponent (n) was developed using process parameters such as temperature, orientation and cross head velocities. Results have shown that mechanical properties can be predicted with a reasonable accuracy within the range of process parameters considered in this study.

Influencing Factors for Improving Accuracy in Prediction of Stress Corrosion Crack Growth Rate in Boiling Water Reactor Operational Condition: Part 1—Prediction of SCC Growth Rate in Terms of Vickers Hardness

2010 ◽  
Author(s):  
Yoichi Takeda ◽  
Zhanpeng Lu ◽  
Takeshi Adachi ◽  
Qunjia Peng ◽  
Jiro Kuniya ◽  
...  
Keyword(s):  
Growth Rate ◽  
Stainless Steel ◽  
Yield Strength ◽  
Strain Hardening ◽  
Crack Growth ◽  
Vickers Hardness ◽  
316L Stainless Steel ◽  
Strain Hardening Exponent ◽  
Theoretical Formulation ◽  
Prediction Curve

It is known that stress corrosion cracking (SCC) found in the operational power plants show complex cracking behaviors and it’s resulted in complex crack shape e.g. crack branching and its uneven crack front. For the cracking near the weldment, this is due to crack penetrated along the complex distribution of residual stress and strain hardened area. In this investigation, in order to advance the accuracy for crack growth prediction with considering such complex fields, theoretical formulation for SCC growth was further modified. Hardness of the materials, which is a measureable parameter even in operational power plant, was focused on to reflect strain hardening of the component like heat affected zone of the weldments. The theoretical formulation for SCC growth has terms with yield strength of the material and strain hardening exponent to describe crack tip strain rate. Strain hardening was simulated by cross rolling with the range of 4 – 32% as thickness reduction. Correlation between yield strength, strain hardening exponent at 288°C and Vickers hardness was obtained by means of tensile tests and hardness tests on 316L stainless steel. It was observed that a monotonic increase in Vickers hardness and yield strength with degree of reduction in thickness worked by cross rolling. Relationship between Vickers hardness and yield strength was found to have linear correlation. Further confirmation was made by plotting the reported mechanical properties data in terms of Vickers hardness. In addition, linear relationship was found between yield strength and strain hardening exponent. These relationships were introduced into SCC theoretical formulation and a SCC growth rate prediction curve in terms of Vickers hardness was proposed. SCC crack growth evaluation tests with selected work hardened 316L stainless steel were performed in oxygenated pure water environment at 288°C to confirm the predictability of the formulation. The prediction curve had a good agreement with available literature data as well as obtained crack growth rates in the hardness range of 140–300HV which was likely expected one in weld HAZ.

scholarly journals Assessment of the Hardening Behavior and Tensile Properties of a Cold-Rolled Bainitic–Ferritic Steel

Materials ◽  
2021 ◽  
Vol 14 (21) ◽  
pp. 6662
Author(s):  
Emilio Bassini ◽  
Antonio Sivo ◽  
Daniele Ugues
Keyword(s):  
Strain Hardening ◽  
High Strength ◽  
Dual Phase ◽  
Low Carbon ◽  
Soft Phase ◽  
Bending Tests ◽  
Ductile Materials ◽  
Hardening Behavior ◽  
Material State ◽  
Cold Rolled

The automotive field is continuously researching safer, high-strength, ductile materials. Nowadays, dual-phase (DP) steels are gaining importance, since they meet all these requirements. Dual-phase steel made of ferrite and bainite is the object of a complete microstructural and mechanical characterization, which includes tensile and bending tests. This specific steel contains ferrite and bainite in equal parts; ferrite is the soft phase while bainite acts as a dispersed reinforcing system. This peculiar microstructure, together with fine dispersed carbides, an extremely low carbon content (0.09 wt %), and a minimal degree of strain hardening (less than 10%) allow this steel to compete with traditional medium-carbon single-phase steels. In this work, a full pearlitic C67 steel containing 0.67% carbon was used as a benchmark to build a comparative study between the DP and SP steels. Moreover, the Crussard–Jaoul (C-J) and Voce analysis were adopted to describe the hardening behavior of the two materials. Using the C-J analysis, it is possible to separately analyze the ferrite and bainite strain hardening and understand which alterations occur to DP steel after being cold rolled. On the other hand, the Voce equation was used to evaluate the dislocation density evolution as a function of the material state.

Strain rate sensitivity and strain hardening response of DP1000 dual phase steel

2018 ◽  
Vol 115 (5) ◽  
pp. 507
Author(s):  
Onur Çavusoglu ◽  
Hakan Gürün ◽  
Serkan Toros ◽  
Ahmet Güral
Keyword(s):  
Tensile Strength ◽  
Strain Rate ◽  
Strain Hardening ◽  
Strain Rate Sensitivity ◽  
Dual Phase Steel ◽  
Rate Sensitivity ◽  
Dual Phase ◽  
Significant Difference ◽  
Load Carrying ◽  
Hardening Coefficient

In this study, strain hardening and strain rate sensitivity behavior of commercial DP1000 dual phase steel have been examined in detail at temperatures of 25 °C, 100 °C, 200 °C and 300 °C, at strain rates of 0.0016 s−1 and 0.16 s−1. As the strain rate has increased, the yield strength has increased but no significant change in tensile strength and strain hardening coefficient has been observed. As the temperature has increased, the yield and tensile strength has decreased in between 25 and 200 °C but it has showed an increase at 300 °C. The strain hardening coefficient has increased in parallel with temperature increase. It has been seen that the strain rate sensitivity has not been affected by temperature. No significant difference in the hardening rate has appeared in between 25 and 200 °C, but the highest value has been calculated at 300 °C. It has been determined that the fracture behavior has occurred earlier and load carrying capacity on necking has reduced with the increase of strain rate and not significantly affected by temperature.

Effect of Steel Properties on Buckling Pressure of Corroded Pipelines

2017 ◽  
Vol 898 ◽  
pp. 741-748 ◽  
Author(s):  
Meng Li ◽  
Hong Zhang ◽  
Meng Ying Xia ◽  
Kai Wu ◽  
Jing Tian Wu ◽  
...  
Keyword(s):  
Finite Element ◽  
Yield Strength ◽  
Strain Hardening ◽  
Corrosion Damage ◽  
Element Model ◽  
External Pressure ◽  
Strain Hardening Exponent ◽  
The Finite Element Method ◽  
Collapse Pressure ◽  
Steel Properties

Due to the harsh environment for submarine pipelines, corrosion damage of the pipeline steels is inevitable. After the corrosion damage, pipelines are prone to failure and may cause serious consequences. The analysis of the effects of different steel properties on the collapse pressure of pipelines with corrosion defects is of importance for the option of appropriate pipeline and avoiding accidents. Based on the finite element method, the finite element model of the pipeline with defects under external pressure was built. Firstly, the accuracy of the numerical model was validated by comparing with previous experimental results. The effects of yield strength and strain hardening exponent on collapse pressure of pipelines with different sizes of defect were discussed in detail. Results showed that the yield strength and strain hardening exponent have different influences on collapse pressure: the collapse pressure increases with the increasing yield strength, and the collapse pressure decreases with the increasing strain hardening exponent.

Mechanical Properties and Fracture Mechanism of TiCp/ZA-12 Composites

2006 ◽  
Vol 324-325 ◽  
pp. 671-674
Author(s):  
Wang Xiang ◽  
Xiao Hua Xue
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Yield Strength ◽  
Cleavage Fracture ◽  
Fracture Mechanism ◽  
Experimental Results ◽  
Fracture Model ◽  
Strength Increase ◽  
Dimple Fracture ◽  
Mixed Fracture

TiCp/ZA-12 composites have been fabricated by XDTM method and stirring-casting techniques. The tests for mechanical properties reveal that the tensile strength and strength increase with increasing fraction of TiC particles. When the fraction of TiC particles increase up to 10%, the tensile strength and yield strength are 390MPa and 340MPa, respectively and they increase by 11% and 17% than that of matrix respectively. From the analysis of fractography we can see that mixed fracture of cleavage fracture and dimple fracture exists in the TiCp/ZA-12 composites, and fractured particles are not found. Finally the fracture model of composites has been established based on the experimental results.

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