Investigation of Fracture Mechanism of Casing-Drilling Steels

2011 ◽  
Vol 197-198 ◽  
pp. 1647-1650 ◽  
Author(s):  
Tian Han Xu ◽  
Yao Rong Feng ◽  
Sheng Yin Song ◽  
Zhi Hao Jin ◽  
Dang Hui Wang
Keyword(s):  
Fracture Surface ◽  
Ductile Fracture ◽  
Fracture Mode ◽  
Fracture Mechanism ◽  
Impact Fracture ◽  
Tensile Fracture ◽  
N80 Steel ◽  
The Impact ◽  
Impact Sample ◽  
Casing Drilling

The paper reports on an investigation of the fracture mechanism of both tensile and impact fracture in three types of casing-drilling steels. The results show that the tensile fracture surface of N80 steel includes fibrous zone, radiation area and shear lip zone, and those of both K55 and P110 steels include two zones; all the tensile fracture surfaces of three types of casing drilling steels show the ductile fracture mode, the ductile fracture mode indicated with dimples is observed on all zones; the impact fracture surface of the N80 steel possesses a combined quasi-cleavage and ductile fracture modes, a single fracture mode is observed on the fracture surface of both K55 and P110 steels, the K55 steel impact sample is fractured in a cleavage brittle manner, whereas the P110 steel impact sample is fractured in a dimpled ductile manner.

Evaluation of Mechanical Properties and Microstructures of Casing-Drilling Steels

2010 ◽  
Vol 146-147 ◽  
pp. 674-677
Author(s):  
Tian Han Xu ◽  
Yao Rong Feng ◽  
Sheng Yin Song ◽  
Zhi Hao Jin
Keyword(s):  
Mechanical Properties ◽  
Fracture Surface ◽  
Impact Energy ◽  
Cleavage Fracture ◽  
Fracture Mechanism ◽  
Tensile Fracture ◽  
Tensile Fracture Surface ◽  
Dimple Fracture ◽  
Drilling Technology ◽  
Casing Drilling

An investigation into the mechanical properties of K55，N80 and P110 steels was carried out for casing-drilling technology. The obvious presence of bright facets on broken K55 Charpy V-Notch (CVN) sample surfaces was indicative of the effect of microstructure on the cleavage fracture. The appearing of bright facet surfaces of K55 was attributed to the microstructure of ferrite and pearlite. The fracture surfaces of N80 and P110 CVN samples included quasi-cleavage fracture mechanism and dimple fracture mechanism, respectively. The tensile fracture surface of all three types of casing-drilling steels included dimple fracture mechanism, both the N80 and P110 specimen show higher UTS and impact energy values compared to the K55 specimen.

Tensile fracture and fractographic analysis of 1045 spheroidized steel under hydrostatic pressure

1990 ◽  
Vol 5 (1) ◽  
pp. 83-91 ◽  
Author(s):  
A. S. Kao ◽  
H. A. Kuhn ◽  
O. Richmond ◽  
W. A. Spitzig
Keyword(s):  
High Pressure ◽  
Hydrostatic Pressure ◽  
Fracture Surface ◽  
Atmospheric Pressure ◽  
Fracture Mechanism ◽  
Shear Crack ◽  
Applied Pressure ◽  
Void Formation ◽  
Tensile Fracture ◽  
Central Crack

Void formation in tensile test under hydrostatic pressure is characterized through quantitative metallography, and the fracture mechanism under pressure is analyzed by fractography. Transition of the fracture surface from the cup-and-cone under atmospheric pressure to a slant structure under high pressure is explained on the basis of the void development leading to fracture and the concomitant change in fracture mechanism. The concept of “shear blocks” is introduced to illustrate the features observed on the fracture surface of specimens tested under high pressure. It is postulated that shear blocks evolve to connect the central crack regions with the shear crack initiated on neck surface due to the severe necking deformation under applied pressure.

Interactive Failure in High Velocity Impact of Two Box Beams

2003 ◽  
Author(s):  
Liang Xue ◽  
Li Zheng ◽  
Tomasz Wierzbicki
Keyword(s):  
Ductile Fracture ◽  
Initial Phase ◽  
Equivalent Strain ◽  
Tensile Fracture ◽  
Recent Attempt ◽  
Mode Iii ◽  
Plane Shear ◽  
Wide Range ◽  
The Impact ◽  
Element Removal

The research reported in the present paper has been motivated mainly by the need of reconstructing the airplane impact damage of the WTC Towers. The initial phase of this catastrophic event was dominated by fracture, leading to breakup and fragmentation of the airplane and severance of a large number of external columns. However, the role of fracture has been de-emphasized in the recent attempt to reconstruct the 9/11 attack [1–3]. The objective of this paper is to raise the phenomenon of ductile fracture to the level of a main factor controlling the initial phase of the September 11th event. Our philosophy is similar to that employed by Lawver et al [4], but we are treating ductile fracture in a much more comprehensive way including the topics of material testing, calibration, validation and finite element implementation. A particular scenario considered is the impact of a corresponding section of the wing of the Boeing 767 into one external box column of a Twin Tower. Real dimensions are taken for the WTC column and the wing section is represented as a thin-walled box beam. Both members undergo extensive plastic deformation and fracture. In developing computer models, special attention was paid to the choice of the element type (shell vs. solid), contact algorithm, element removal (erosion) option, and above all the fracture criterion. Most calculations were done using LS-DYNA for several combinations of the equivalent strain to fracture of the aluminum alloy wing and the steel columns. In addition five ABAQUS runs were made with a newly developed criterion for ductile fracture with a cut-off value for negative triaxialities. Impact velocities considered ranged from 120 to 480 m/sec where 240 m/sec was the actual impact speed of the Boeing 767. It was found that the damage process is localized in the immediate velocity of the impact area. The fracture process initiates at the impacting flanges in the Mode III out-of-plane shear, continues down the webs as a combined shear/tension (tearing) and finally ends up as a tensile fracture of the rear flanges. While the airplane wing box was almost always completely cut, the WTC column was often partially penetrated for a wide range of the equivalent strain to fracture. It was also found that introducing a modified fracture locus changes the sequence of failure pattern as well as the mode of fracture.

Effect of Temperature on Impact Properties of ZA27 Alloy

2012 ◽  
Vol 476-478 ◽  
pp. 75-80 ◽  
Author(s):  
Li Ping Zhong ◽  
Jia Yong Si ◽  
Zi Qiao Zheng
Keyword(s):  
Impact Toughness ◽  
Fracture Surface ◽  
Impact Energy ◽  
Impact Testing ◽  
Impact Fracture ◽  
Impact Behavior ◽  
Effect Of Temperature ◽  
Za27 Alloy ◽  
Different Temperatures ◽  
The Impact

The impact toughness of ZA27 alloy at different temperatures is investigated by pendulum impact testing. In addition, the morphology of impact fracture surface observed by SEM. The results indicate that impact energy of ZA27 alloy is reduced with the temperature rising when the temperature is lower than 100°C. At 100°C to 200°C, impact energy increase as the temperature rising. And when the temperature reaches to 250°C, impact energy suddenly descend. Impact energy is the highest and reaches to 72.768J at 20°C. At impact fracture surface, it is mostly tear ridges and dimples. The higher the impact energy is, the more obvious the characteristic of tear ridges is. Furthermore, dimples are small and distribute more uniformly. Lower the impact energy, the less distinct of tear ridges. Dimples are larger and deeper, their distribution are not uniform. Impact behavior of material could be evaluated by the width of impact curve. The wider the peak of impact curve, the higher the impact toughness. But impact toughness is worse while peak is narrow.

The Effects of Rolling and Annealing on the High Speed Impact Deformation Behavior of Mg-3%Li-1%Nd Alloy

2011 ◽  
Vol 295-297 ◽  
pp. 2261-2266 ◽  
Author(s):  
Teng Liu ◽  
Gui Ying Sha ◽  
He Nan Wang ◽  
Xiao Lei Wang ◽  
Tao Yu ◽  
...  
Keyword(s):  
Microstructure Evolution ◽  
Fracture Mechanism ◽  
Deformation Behavior ◽  
High Speed ◽  
Impact Fracture ◽  
High Speed Impact ◽  
Impact Deformation ◽  
The Impact ◽  
The Relationship

In this paper, the impact deformation behavior of the as-rolled and annealed Mg-3%Li-1%Nd alloy was investigated by using the Hopkinson compressive bar. The effects of rolling and annealing on the high speed impact deformation behavior were analyzed. The relationship between microstructure evolution and impact fracture mechanism was discussed.

BRITTLE-DUCTILE TRANSITION AND SCALE DEPENDENCE: FRACTAL DIMENSION OF FRACTURE SURFACE OF MATERIALS

Fractals ◽  
1999 ◽  
Vol 07 (02) ◽  
pp. 159-168 ◽  
Author(s):  
TOSHITAKA IKESHOJI ◽  
TADASHI SHIOYA
Keyword(s):  
Fractal Dimension ◽  
Brittle Fracture ◽  
Fracture Surface ◽  
Ductile Fracture ◽  
Stress Triaxiality ◽  
Scale Dependence ◽  
Tensile Fracture ◽  
Scanning Electron Micrographs ◽  
Fracture Surfaces ◽  
Brittle Ductile Transition

The fractal dimension of fracture surfaces obtained within brittle-ductile transition regime is evaluated at various observation scales. Fracture surfaces are generated by the tensile fracture test. The brittle-ductile transition is accomplished by using the round-notched bar specimens with various notch radii, which cause the variation in stress triaxiality. The specimens are manufactured from mild steel, steel and cast-iron bar. The fracture model is identified according to the observation through scanning electron micrographs. The fractal dimension for ductile fracture surfaces is almost constant despite variations in observing scale and changes in stress triaxiality. Meanwhile, the fractal dimension on brittle fracture surfaces shows the different values for macroscopic and microscopic observing scales. This transition-like scale dependence of fractal dimension for brittle fracture surfaces is considered to reflect such a characteristic of the fracture i.e. its specific length in microscopic fracture mechanism. The existence of transition in fractal dimension with observing scale is considered to be an index, used to distinguish the ductile fracture surface from the brittle fracture one.

Impact Properties of TiC/Fe at Elevated Temperatures

2010 ◽  
Vol 434-435 ◽  
pp. 113-115
Author(s):  
Yan Rong Bao ◽  
Bin Li ◽  
Zong De Liu ◽  
Zhi Jian Bao
Keyword(s):  
Fracture Surface ◽  
Impact Test ◽  
Elevated Temperatures ◽  
Impact Fracture ◽  
X Ray Diffraction ◽  
Impact Properties ◽  
X Ray ◽  
Before And After ◽  
Different Temperatures ◽  
The Impact

The impact properties of TiC-Fe composite at different temperatures prepared by SHS / PHIP technique were investigated by impact test which was conducted in air from 20°C to 100020°C. Morphology of the impact fracture surface was observed by scanning electron microscope (SEM) and phase composition before and after the impact test was analyzed with X-Ray Diffraction. The results indicate that the impact toughness of TiC-Fe composite increases significantly with the temperature increasing above 700°C, representing a minimum value at 700°C. The impact fracture of TiC-Fe composite at room temperature, 700°C, 900°C and 1000°C is mainly brittle, showing certain plasticity with morphology of dimples as the temperature increases above 700°C. A small amount of Fe2O3 exists in the fracture surface, indicating TiC-Fe composite is oxidized partially during the impact test at elevated temperatures.

Microstructural and Mechanical Behaviour Evaluation of Mg-Al-Zn Alloy Friction Stir Welded Joint

2020 ◽  
Vol 17 (3) ◽  
pp. 8150-8159
Author(s):  
Kulwant Singh ◽  
Gurbhinder Singh ◽  
Harmeet Singh
Keyword(s):  
Heat Treatment ◽  
Friction Stir Welding ◽  
Magnesium Alloys ◽  
Mechanical Performance ◽  
Fuel Efficiency ◽  
Research Work ◽  
Grain Structure ◽  
Tensile Fracture ◽  
Friction Stir ◽  
The Impact

The weight reduction concept is most effective to reduce the emissions of greenhouse gases from vehicles, which also improves fuel efficiency. Amongst lightweight materials, magnesium alloys are attractive to the automotive sector as a structural material. Welding feasibility of magnesium alloys acts as an influential role in its usage for lightweight prospects. Friction stir welding (FSW) is an appropriate technique as compared to other welding techniques to join magnesium alloys. Field of friction stir welding is emerging in the current scenario. The friction stir welding technique has been selected to weld AZ91 magnesium alloys in the current research work. The microstructure and mechanical characteristics of the produced FSW butt joints have been investigated. Further, the influence of post welding heat treatment (at 260 °C for 1 h) on these properties has also been examined. Post welding heat treatment (PWHT) resulted in the improvement of the grain structure of weld zones which affected the mechanical performance of the joints. After heat treatment, the tensile strength and elongation of the joint increased by 12.6 % and 31.9 % respectively. It is proven that after PWHT, the microhardness of the stir zone reduced and a comparatively smoothened microhardness profile of the FSW joint obtained. No considerable variation in the location of the tensile fracture was witnessed after PWHT. The results show that the impact toughness of the weld joints further decreases after post welding heat treatment.

scholarly journals Optimization of proppant parameters for CBM extraction using hydrofracturing by orthogonal experimental process

2020 ◽  
Vol 17 (3) ◽  
pp. 493-505 ◽  
Author(s):  
Haoze Li ◽  
Bingxiang Huang ◽  
Qingying Cheng ◽  
Xinglong Zhao
Keyword(s):  
Particle Size ◽  
Orthogonal Test ◽  
Coal Mass ◽  
Tensile Fracture ◽  
Experimental Conditions ◽  
Embedded Value ◽  
Fracture Area ◽  
Creep Time ◽  
Experimental Process ◽  
The Impact

Abstract Proppant placement concentration, particle size and creep time are important factors that affect the embedment of proppant into coal. Based on multistage creep, an orthogonal test is conducted, and an optimal proppant scheme for different closure stresses obtained. The results show that with increased proppant placement concentration, the number of coal fractures increases and the elastic modulus of the fracture area decreases. As the proppant particle size decreases, the plasticity of fracture-proppant assemblies increases gradually. The yield limit is highest when the particle size is 20/40 mesh. During the proppant embedding process, localization or uneven distribution of proppant results in tensile stress parallel to the fracture surface, which induces tensile fracture in the coal. In the fracture-proppant assembly areas, proppant fractures are severe and yield lines appear. As proppant concentration increases, more energy is accumulated during the proppant compaction stage, resulting in energy release producing craters and crevasses. The energy released also causes increased stress in the proppant-coal contact area and fracturing to the coal mass. The longer the creep time, the weaker the impact and the smaller is fluctuation. Moreover, we find that the orthogonal test can effectively analyze the importance of each parameter. Proppant placement concentration was found to have the highest influence on the process of proppant embedding into coal, followed by particle size and then time. Under experimental conditions, the lowest proppant-embedded value in coal samples was observed with proppant placement concentration of 2 kg m−2 and particle size of 20/40 mesh.

Sign in / Sign up

Export Citation Format

Share Document