Material Design of Offshore Linepipe Steels for Ultra Deep Water Application

2019 ◽  
Author(s):  
Kyono Yasuda ◽  
Junji Shimamura ◽  
Satoshi Igi ◽  
Ryuji Muraoka
Keyword(s):  
Mechanical Properties ◽  
Yield Strength ◽  
Deep Water ◽  
Bauschinger Effect ◽  
Reverse Flow ◽  
Material Design ◽  
Compressive Yield Strength ◽  
Water Application ◽  
Offshore Pipeline ◽  
Lower Temperature

Abstract Offshore pipeline projects have been expanded to deeper water region and the linepipes are required to have higher resistance against collapse by external pressure. The collapse resistance is mainly dominated by pipe geometry and compressive yield strength. For deep water application, diameter to thickness ratio (D/t) and pipe roundness are key factors. On the other hand, the mechanical properties in each circumferential position is dramatically changed by cyclic deformation through a pipe forming process. Therefore, in order to improve compressive yield strength of pipes, it is important to consider the Bauschinger effect caused by pipe expansion. The mechanism of this effect is understood that internal stress is generated by accumulation of dislocation and it reduces reverse flow stress. In this study, the microscopic deformation behavior was analyzed from FEM calculation, it was found that multi-phases microstructure enhanced the microscopic heterogeneous deformation adjacent to the boundary between soft and hard phases. Therefore, homogenized microstructure inhibits the Bauschinger effect. In addition, the materials of offshore pipeline should have other properties such as low temperature toughness and sour resistance. It is well known that fine grained microstructure improves the lower temperature toughness. For achieving high compressive yield strength and good lower temperature toughness, the effect of chemistry and rolling condition were investigated to obtain fine and homogeneous microstructure. Based on laboratory results, mill trial tests were carried out for Grade X65 linepipes with heavy gauge by TMCP. Full scale collapse test was also conducted after pipe coating heating. In this paper, material design concept and its mechanical properties of developed pipes were introduced.

Collapse Resistance Under Combined External Pressure and Bending Deformation of Coated Linepipe

2020 ◽  
Author(s):  
Takahiro Sakimoto ◽  
Hisakazu Tajika ◽  
Tsunehisa Handa ◽  
Yoshiaki Murakami ◽  
Satoshi Igi ◽  
...  
Keyword(s):  
Yield Strength ◽  
Deep Water ◽  
Thermal Cycle ◽  
Bauschinger Effect ◽  
Heating Temperature ◽  
External Pressure ◽  
Compressive Yield Strength ◽  
Heat Cycle ◽  
Bending Deformation ◽  
Collapse Resistance

Abstract As offshore pipeline projects have expanded to deeper water regions with depths of more than 2 000 m, higher resistance against collapse by external pressure is now required in linepipe. Collapse resistance is mainly controlled by the pipe geometry and compressive yield strength. In UOE pipe, the compressive yield strength along the circumferential direction changes dramatically due to tensile pre-strain that occurs in pipe forming processes such as the expansion process. In order to improve the compressive yield strength of pipes, it is important to consider the Bauschinger effect caused by pipe expansion. As the mechanism of this effect, it is understood that internal stress is generated by the accumulation of dislocations, and this reduces reverse flow stress. Compressive yield strength is also changed by the thermal cycle associated with application of fusion-bond epoxy in pipe anti-corrosion coating by induction heating. In the typical thermal heat cycle of this coating process, the maximum heating temperature is from 200 °C to 250 °C. In this case, compressive yield strength increases as an effect of the thermal cycle, resulting in increased collapse resistance. Thus, for deep water application of UEO linepipe, it is important to clarify the conflicting effects of the Bauschinger effect and the thermal heat cycle on compressive yield strength. During installation of deep water pipelines by a method such as J-lay, curvature is imposed on the pipe axis, but the circumferential bending that leads to ovalization is determined by the interaction of the curvature of bending deformation. This bending deformation decreases collapse resistance. The interaction of external pressure and bending is also important when evaluating collapse. Against this background, this study discusses the collapse criteria for coated linepipe and their bending interaction against collapse based on a full-scale collapse test under external pressure with and without bending loading. The effect of the thermal heat cycle on linepipe collapse criteria is also discussed based on the results of tensile pre-strain tests with simulation of the thermal cycle and a collapse calculation by FEA.

Effect of Tensile Pre-Strain on Collapse Pressure of Coated Linepipe

2019 ◽  
Author(s):  
Takahiro Sakimoto ◽  
Tsunehisa Handa ◽  
Hisakazu Tajika ◽  
Yoshiaki Murakami ◽  
Joe Kondo
Keyword(s):  
Yield Strength ◽  
Thermal Cycle ◽  
Bauschinger Effect ◽  
Reverse Flow ◽  
Heating Process ◽  
Compressive Yield Strength ◽  
Maximum Heat ◽  
Collapse Pressure ◽  
Heat Cycle ◽  
Collapse Resistance

Abstract As offshore pipeline projects have expanded to deeper water regions with depths of more than 2,000 m, linepipes are required to have higher resistance against collapse by external pressure. Collapse resistance is mainly controlled by the pipe geometry and compressive yield strength. In UOE pipe, the compressive yield strength along the circumferential direction changes dramatically due to tensile pre-strain that occurs in pipe forming processes such as the expansion process. In order to improve the compressive yield strength of pipes, it is important to consider the Bauschinger effect caused by pipe expansion. As the mechanism of this effect, it is understood that internal stress is generated by the accumulation of dislocations, and this reduces reverse flow stress. Compressive yield strength is also changed by the thermal cycle associated with application of fusion-bond epoxy in pipe anti-corrosion coating by the induction heating process. In the typical thermal heat cycle of this coating process, the maximum heat temperature is from 200 °C to 250 °C. In this case, compressive yield strength increases as an effect of the thermal cycle, resulting in increased collapse resistance. Thus, for deep water application of UEO linepipe, it is important to clarify the conflicting effects of the Bauschinger effect and the thermal heat cycle on compressive yield strength. Based on this background, in this study, the combined effect of the Bauschinger effect and the thermal heat cycle on compressive stress is investigated by conducting tensile pre-strain tests and simulation of the thermal cycle associated with coating. Compressive yield strength was obtained for several pre-strain and thermal cycle conditions, and the collapse pressure was calculated by an FE analysis based on the obtained compressive yield strength. This study discusses the effect of tensile pre-strain on the collapse pressure of linepipes with these simulated thermal heat cycles.

Effect of Bubble Inclusions on the Mechanical Properties of Cast Poly-Methyl Metacrylate

1972 ◽  
Vol 94 (4) ◽  
pp. 847-852 ◽  
Author(s):  
J. D. Stachiw
Keyword(s):  
Mechanical Properties ◽  
Yield Strength ◽  
Loading Condition ◽  
Stress Raiser ◽  
Compressive Yield Strength ◽  
Compressive Test ◽  
Acrylic Plastic ◽  
Methyl Metacrylate ◽  
As Stress ◽  
Stress Raisers

Bubble inclusions present in cast acrylic plastic generally degrade the mechanical properties of the material. To evaluate the effect of bubbles on the mechanical strength of acrylic plastic, 120 tensile and compressive test specimens were machined from massive acrylic castings with bubble inclusions. The specimens were tested under uniaxial loading condition and effect of bubbles on tensile and compressive strength noted. The stress raiser effect of bubbles caused the tensile specimens to fail at stresses 7 to 30 percent lower than observed in specimens without bubbles. The compressive yield strength was not affected by bubbles. However, here the bubbles served as stress raisers also and caused cracks to initiate at the bubble surfaces when the yield strength of acrylic plastic was reached.

Structural, Physical and Mechanical Properties of Mg-Al Alloys Processed under CO2 Atmosphere

2012 ◽  
Vol 545 ◽  
pp. 247-250 ◽  
Author(s):  
Subramanian Jayalakshmi ◽  
Khoo Chee Guan ◽  
Kuma Joshua ◽  
Manoj Gupta
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Yield Strength ◽  
Magnesium Alloys ◽  
Physical And Mechanical Properties ◽  
Melting Process ◽  
Al Alloys ◽  
Compressive Yield Strength ◽  
Protective Atmospheres

Magnesium alloys are the lightest structural materials known that are increasingly replacing steel and aluminium. However, due to its flammable nature, protective atmospheres are employed during Mg-alloy production. In this novel work, Mg-Al alloys with ~3 and ~5 wt.% Al were processed in CO2atmosphere, so as to utilize the CO2during the melting process. The cast Mg-Al alloys were extruded and studied for their structural, physical and mechanical properties. Results showed improvements in mechanical properties such as hardness, tensile strength and compressive yield strength. The improvement in properties was attributed to thein situformation of Al4C3arising due to molten metal-carbon interaction. It is noteworthy that the incorporation of CO2during processing did not adversely affect the mechanical properties of the alloys. Further, the process is eco-friendly as it not only utilized CO2, but also eliminates use of harmful cover gases.

scholarly journals Achieving High Yield Strength and Ductility in As-Extruded Mg-0.5Sr Alloy by High Mn–Alloying

Materials ◽  
2020 ◽  
Vol 13 (18) ◽  
pp. 4176
Author(s):  
Shibo Zhou ◽  
Xiongjiangchuan He ◽  
Peng Peng ◽  
Tingting Liu ◽  
Guangmin Sheng ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Grain Size ◽  
Yield Strength ◽  
Tensile Yield Strength ◽  
High Yield ◽  
Compressive Yield Strength ◽  
High Yield Strength ◽  
Pinning Effect ◽  
Small Grains ◽  
Strength And Ductility

The effect of Mn on the microstructure and mechanical properties of as-extruded Mg-0.5Sr alloy were discussed in this work. The results showed that high Mn alloying (2 wt.%) could significantly improve the mechanical properties of the alloys, namely, the tensile and compressive yield strength. The grain size of as-extruded Mg-0.5Sr alloys significantly was refined from 2.78 μm to 1.15 μm due to the pinning effect by fine α-Mn precipitates during the extrusion. Moreover, it also showed that the tensile yield strength and the compressive yield strength of Mg-0.5Sr-2Mn alloy were 32 and 40 percent age higher than those of Mg-0.5Sr alloy, respectively. Moreover, the strain hardening behaviors of the Mg-0.5Sr-2Mn alloy were discussed, which proved that a large number of small grains and texture have an important role in improving mechanical properties.

scholarly journals Utilization of Recycled Thermoplastic Nylon Combined with Virgin Nylon and the Effect on its Mechanical Properties as a Denture Base Material

2019 ◽  
pp. 51-55
Author(s):  
Haslinda Z Tamin ◽  
Siti Wahyuni ◽  
Ismet Danial Nasution
Keyword(s):  
Mechanical Properties ◽  
Yield Strength ◽  
Modulus Of Elasticity ◽  
Statistical Significance ◽  
Testing Machine ◽  
Base Material ◽  
Bending Test ◽  
Laboratory Research ◽  
Compressive Yield Strength ◽  
Mechanical Degradation

The injection molding process of thermoplastic nylon produces nylon residues in the form of sprue. Nylon residues are non-biodegradable which causes serious ecological problems, hence recycling becomes a necessity. However, recycled nylon is subjected to thermal, oxidative, and mechanical degradation during process which may decrease the mechanical properties of recycled nylon. In order to overcome the decreased mechanical properties of recycled nylon, modification by combining recycled nylon with virgin nylon is considered. Aim: This study aimed to determine the effect of adding virgin nylon into recycled nylon on the modulus of elasticity and compressive yield strength. Settings and Design: Experimental laboratory research. Methods and Materials: A total of 45 samples were used. Samples were divided into 3 groups which include 100% virgin nylon as control (A), 100% recycled nylon (B) and combination of 60% virgin nylon with 40% recycled nylon (C). The samples were tested using Universal Testing Machine (Tensilon RTF, Japan) with three point bending test and compression test with the speed of 5mm/min with ultimate load. Statistical analysis used: The obtained results were analyzed using Univarian test, One-way ANOVA test and Turkey’s Honestly Significant Different test. Result: There was statistical significance in adding virgin nylon into recycled nylon on its mechanical properties, namely modulus of elasticity and compressive yield strength (p<0.05). Conclusion: The combination of 60% virgin nylon with 40% recycled nylon has better elastic modulus and compressive yield strength values compared to 100% recycled nylon.

Single sample method for assessing the Baushinger effect

2020 ◽  
Vol 86 (7) ◽  
pp. 55-58
Author(s):  
A. D. Khvan ◽  
D. V. Khvan ◽  
A. A. Voropaev
Keyword(s):  
Plastic Deformation ◽  
Stress State ◽  
Yield Strength ◽  
Bauschinger Effect ◽  
Calculated Data ◽  
Compressive Yield Strength ◽  
Special Device ◽  
Compression Tests ◽  
Traditional Procedure

The Bauschinger effect is one of the fundamental properties of most metal alloys exposed to plastic deformation under non-monotonic loading. Development of the methods for quantifying this effect is one the important issues of the theory of plasticity. Calculation of the parameter characterizing the aforementioned effect is required for determination of the stress state in plastically deformable blanks upon pressure metal treatment. The value of the parameter (determined in standard tensile tests followed by subsequent compression of samples) is defined by the ratio of the conditional yield strength of the sample under compression to the value of the preliminary tensile stress. A series of cylindrical samples (~10 pcs.) is usually taken for tensile-compression tests. According to the traditional procedure, long-size standard specimens are pre-stretched to various degrees of plastic deformation. After that short specimens are cut out from those specimens for compression tests to determine the conditional compressive yield strength with a tolerance of 0.2% for plastic deformation. Such a procedure is rather time consuming and expensive. We propose and develop a new single-model method for estimating the Bauschinger effect which consists in testing of a single long-size specimen for tension followed by compression of the specimen in a special device providing deformation of a previously stretched specimen without flexure under conditions of a linear stress state. The device was designed, manufactured and underwent the appropriate tests. The device contains supporting elements in the form of conical-shaped sectors that prevent flexure of a long cylindrical specimen upon compression, a ratio of the working part length to diameter ranges from 5 to 10. The results of experimental determination of the parameter β characterizing the indicated effect are presented. The results of comparing the values of the parameter β determined by the developed and traditional methods revealed the possibility of determining the parameter β using the proposed method. To reduce the complexity of performing tests related to determination of the parameter β we approximated it in the form of an exponent as a function of the magnitude of plastic deformation and determine the only one value of β0 under plastic deformations exceeding 0.05. In this regard, β0 can be considered a new characteristic of the material. The calculated data are in good agreement with the experimental results. The values of β0 are determined for a number of studied steel grades.

Microstructure and Mechanical Properties Investigation of New Al10Cr12Mn28Fe(50-x)Ni(x) High Entropy Alloys

2020 ◽  
Vol 998 ◽  
pp. 9-14
Author(s):  
Ahmed W. Abdel-Ghany ◽  
Sally Elkatatny ◽  
Mohamed Abdel Hady Gepreel
Keyword(s):  
Mechanical Properties ◽  
Yield Strength ◽  
Compressive Yield Strength ◽  
High Entropy Alloys ◽  
High Ductility ◽  
Cast Material ◽  
High Entropy ◽  
Arc Melting ◽  
Microstructure And Mechanical Properties ◽  
Cast Alloys

In the present study, two newly developed non-equiatomic high entropy Al10Cr12Mn28Fe(50-x)Ni(x) alloys (x= 20 & 15 at%, namely: Ni20 & Ni15, respectively) are investigated. The studied HEAs were designed based on thermodynamic principles to maintain high ductility and improve strength. Ingots were prepared using arc-melting then microstructure examinations and mechanical properties for the as-cast alloys were done. The mechanical properties were enhanced for the as-cast material, compared with previously introduced HEAs of the same system, namely Al5Cr12Mn28Fe35Ni20, (Al5) and Al10Cr12Mn23Fe35Ni20, (Al10). Al10Cr12Mn28Fe30Ni20 (Ni20) HEA generally shows the highest compressive yield strength which was improved by ∼7% when compared with previously introduced Al10.

Effect of sintering parameters on the microstructure and compressive mechanical properties of porous Fe scaffold fabricated using 3D printing and pressure less microwave sintering

2020 ◽  
Vol 234 (21) ◽  
pp. 4305-4320
Author(s):  
Dipesh Kumar Mishra ◽  
Pulak Mohan Pandey
Keyword(s):  
Mechanical Properties ◽  
Yield Strength ◽  
Heating Rate ◽  
Sintering Temperature ◽  
Electron Backscatter Diffraction ◽  
Microwave Sintering ◽  
Compressive Yield Strength ◽  
Soaking Time ◽  
Electron Backscatter ◽  
Backscatter Diffraction

The demand for the porous scaffold has been increasing globally in the biomedical field due to numerous advantages over dense structures like high damping capacity, high specific strength, and improved cell integration growth. In the present study, porous iron scaffolds were fabricated using micro-extrusion-based three-dimensional printing and pressureless microwave sintering. For the preparation of samples, metal-based polymeric ink was developed. Thereafter, cylindrical samples were printed and then sintered in a microwave sintering furnace. The experimental investigations were performed to estimate the effect of sintering parameters such as sintering temperature, heating rate and soaking time on the compressive and microstructural property of the fabricated samples. Microstructural characterization was done using the electron backscatter diffraction technique. The experimental observations deduced that the compressive yield strength and apparent density of the sintered sample increased with the increase in sintering temperature and decreased with a further rise in temperature. Moreover, the electron backscatter diffraction analysis unveiled that the high heating rate resulted in the reduction of compressive yield strength due to rapid grain growth. Additionally, the significant effect of soaking time on the compressive mechanical properties was also noticed due to the increase in the grain size diameter. From the X-ray diffraction plot, it was found that there was no contamination present in the fabricated scaffold. In order to evaluate the process capability, a case study was performed wherein the topologically ordered porous structure of iron was fabricated at optimum sintering parameters.

Structure Change and Improvement of the Mechanical Properties of Lotus-Type Porous Copper by ECAE Process

2009 ◽  
Vol 620-622 ◽  
pp. 757-760 ◽  
Author(s):  
Juan Lobos ◽  
Shinsuke Suzuki ◽  
Hiroshi Utsunomiya ◽  
Hideo Nakajima
Keyword(s):  
Mechanical Properties ◽  
Yield Strength ◽  
Deformation Behavior ◽  
Cell Walls ◽  
Equal Channel Angular Extrusion ◽  
Structure Change ◽  
Compressive Yield Strength ◽  
Channel Angle ◽  
Porous Copper ◽  
Cylindrical Pores

Deformation behavior of lotus-type porous copper with long cylindrical pores aligned in one direction through equal-channel angular extrusion (ECAE) process was investigated using a die with channel angle of 150º. Although the density slightly increased after every pass, the porous structure remains in the process. The Vickers hardness and the compressive yield strength of lotus copper increased through the ECAE process. The compressive yield strength after 3 passes increased up to 10 times larger than that before processing. The deformation of lotus copper takes place by buckling and the shearing of the cell walls. The increase in hardness is considered to be caused by work hardening.

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