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RISS 인기검색어
- 검색키워드
- 저자 : M. A. Mohtadi‑Bonab (검색결과 3 건)
- 무료
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M. A. Mohtadi‑Bonab,H. Ghesmati‑Kucheki 대한금속·재료학회 2019 METALS AND MATERIALS International Vol.25 No.5
Currently, thousands of kilometers of pipeline steels are transferring hydrocarbon fluids such as oil and natural gas in theworld. Due to the fact that these pipes transport corrosive and high-pressure fluids from harsh environments, they are damagedand eventually degraded. Previous studies showed that sulphide stress cracking, hydrogen induced cracking (HIC) andstress corrosion cracking are the main destructive factors in these types of pipes. This paper focused on the HIC related failurein pipeline steel, since the role of texture and grain boundary character has not been completely recognized. Moreover, ifpipeline damage is occurred by hydrogen cracks, besides the environmental pollutions, it will cost a lot to repair or replacethe damaged pipeline steels. In this research, the factors influencing the initiation and propagation of the HIC cracks, suchas hydrogen traps, inclusions, precipitates, microstructure and texture of steel have been investigated. Also, the existingsolutions for improving the steel resistance to the HIC have been investigated based on the control of micro-alloy elements,texture and grain boundary engineering. For instance, some special dominant texture components and coincidence site latticeboundaries decrease the HIC susceptibility by providing the resistant path for crack propagation.
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M. A. Mohtadi-Bonab,M. Eskandari,R. Karimdadashi,J. A. Szpunar 대한금속·재료학회 2017 METALS AND MATERIALS International Vol.23 No.4
In this study, the surface and cross section of an as-received API X70 pipeline steel was studied by SEM and EDStechniques in order to categorize the shape and morphology of inclusions. Then, an electrochemical hydrogencharging using a mixed solution of 0.2 M sulfuric acid and 3 g/l ammonium thiocyanate has been utilized to createhydrogen cracks in X70 steel. After hydrogen charging experiments, the cross section of this steel has been accuratelychecked by SEM in order to find out hydrogen cracks. The region of hydrogen cracks was investigated bySEM and EBSD techniques to predict the role of different microstructural parameters involving hydrogen inducedcracking (HIC) phenomenon. The results showed that inclusions were randomly distributed in the cross section oftested specimens. Moreover, different types of inclusions in as-received X70 steel were found. However, onlyinclusions which were hard, brittle and incoherent with the metal matrix, such as manganese sulfide and carbonitrideprecipitates, were recognized to be harmful to HIC phenomenon. Moreover, HIC cracks propagate dominantlyin transgraular manner through differently oriented grains with no clear preferential trend. Moreover, adifferent type of HIC crack with about 15-20 degrees of deviation from the rolling direction was found and studiedby EBSD technique and role of micro-texture parameters on HIC was discussed.
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Farzin Azimpour-Shishevan,Hamit Akbulut,M. A. Mohtadi-Bonab 한국섬유공학회 2020 Fibers and polymers Vol.21 No.11
The effects of intra-ply hybridization on mechanical and thermal properties of carbon/basalt fibers reinforcedepoxy composites were experimentally investigated. Combination of superior mechanical properties of carbon fiber, goodthermal stability and basalt fiber toughness is the main purpose of designing of these composites. Three types ofhomogeneous carbon fiber reinforced polymer (CFRP), basalt fiber reinforced polymer (BFRP) and intra-ply hybrid ofcarbon/basalt reinforced polymer (CBFRP) composites were fabricated by using vacuum assisted resin infusion molding(VARIM) method. All fabricated composite plates were cut according to ASTM standard. The effect of incorporation ofbasalt fiber with carbon fiber on mechanical properties, such as modulus of elasticity, tensile strength, flexural modulus,flexural strength and inter laminar shear strength (ILSS) were studied by bending, tensile and short beam shear (SBS)experiments. Measurement of thermal conductivity, dynamic mechanic analyze (DMA), thermogravimetric analyze (TGA)tests were also carried out for thermal characterization of fabricated homogeneous and hybrid composites. Furthermore,dynamic drop test (DDT) was used to evaluate hybridization effect on hydrophobicity of composites. The results indicatedthat the CBFP hybrid composites perform a moderate mechanical performance between homogeneous CFRP and BFRPcomposites. On the other hand, incorporation of basalt fiber in the structure of carbon fiber composite not only enhances thethermal stability of composites but also moderates the fabrication price by alternating cheaper basalt fiber with expensivecarbon fiber.
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