Mechanical Properties and Bending Behaviors of Low Temperature Toughness Linepipe Steels

2007 ◽  
Author(s):  
Seong Soo Ahn ◽  
Woo Yeon Cho ◽  
Tae-Yang Yoon ◽  
Jang-Yong Yoo
Keyword(s):  
Mechanical Properties ◽  
Transition Temperature ◽  
Low Temperature ◽  
Axial Compression ◽  
Large Scale ◽  
Steel Plate ◽  
Compressive Strain ◽  
Compression Force ◽  
X80 Steel ◽  
Low Temperature Toughness

API-X70 and X80 steel with good low temperature toughness were developed. The microstructure and mechanical properties of API-X70 steel plate and pipe were investigated and the buckling behavior of X80 steel pipe was evaluated through large scale deformation tester. API-X70 steels with 30 mm thickness were manufactured by finished rolling below Ar3. The microstructure was composed of polygonal ferrite with subgrain network, degenerated pearlite and bainite. The yield strengths of API-X70 pipes were lower than those of plates, while the tensile strengths were similar in both states. The Charpy upper shelf energy of API-X70 steel plate was about 350 J and the energy transition temperature was below −100 °C. The separations were observed on the DWTT fracture surface of API-X70 steel plate. The DWTT 85 SA% transition temperature of plate was below −30 °C. It was conjectured that the separation associated with the low temperature rolling might increase the strength without deterioration of DWTT properties. API-X80 steels with 19mm thickness were fabricated with finished rolling above Ar3 and pipes with 30” diameter were made with R/B process. The deformation capacity of X80 linepipe was evaluated by large scale deforming machine operating under the loading of bending and axial compression force. It was showed that 2nd moment term should be calculated more correctly to measure the accurate critical compressive strain of pipe in the loading of bending and axial compression force. The compressive axial force had a little effect on the peak moment but changed the deformation pattern and state of critical compressive strain of linepipe. It was found that X80 linepipe used in this study was within the specification of DNV and API codes in terms of buckling capacity.

Effect of Intercritical Quenching on Microstructure and Mechanical Properties of Ultra Low Carbon Heavy Steel Plate

2010 ◽  
Vol 152-153 ◽  
pp. 1371-1376
Author(s):  
De Hui Zou ◽  
Zhi Fang Peng ◽  
Ping He Li ◽  
Ai Min Guo
Keyword(s):  
Mechanical Properties ◽  
Low Temperature ◽  
Ambient Temperature ◽  
Steel Plate ◽  
Cold Water ◽  
Annealing Treatment ◽  
Low Carbon ◽  
Comprehensive Properties ◽  
Microstructure And Mechanical Properties ◽  
Low Temperature Toughness

The Effect of intercritical quencing on microstructure and mechanical properties of ultra low carbon heavy steel plate were studied by utilizing SEM, TEM, tensile and impact tests. The specimens were firstly subjected to an annealing treatment at 930 oC followed by quenching to ambient temperature, then were repeatedly annealing at the temperatures being varied in the range of 600~870 oC, and then repeatedly quenched to ambient temperature in cold water. When the intercritical quenching was just slightly above Ac1, the strength and low temperature toughness were remarkably deteriorated attributing to the massive grain and some twins in the bainite islands. However, the more when the annealing temperature increased higher than Ac1 but still below Ac3, the more regions can be austenized, which cause the average of carbon content in the austenized regions to be relatively low. So it was difficult that these austenite regions changed into twin martensites after interctitical quenched. Then the comprehensive properties including low temperature toughness became good again.

Mechanical Properties of Large Scale Confined Concrete

2011 ◽  
Vol 94-96 ◽  
pp. 1983-1988
Author(s):  
Jia Song ◽  
Zhen Bao Li ◽  
Yong Ping Xie ◽  
Xiu Li Du ◽  
Yue Gao
Keyword(s):  
Mechanical Properties ◽  
Experimental Study ◽  
Axial Compression ◽  
Large Scale ◽  
Plain Concrete ◽  
Concrete Columns ◽  
Confined Concrete ◽  
Transverse Reinforcement ◽  
Test Results ◽  
Reinforcement Configuration

An experimental study was made of the mechanical properties of large scale confined concrete subjected to the axial compression test. Eleven tied concrete columns and six plain concrete prisms were tested. In the test, each specimen had the same transverse reinforcement configuration, and similar volumetric ratio of lateral steel, while different size. The test results in this paper indicate that the size of the specimen has no obvious relationship with the ultimate strength, however, it does affect the post-peak ductility to some extent. As a supplement to the experimental study, a finite element method was adopted to imitate the mechanical behavior of the confined concrete under axial compression. The results of the imitation in this paper indicate the confinement mechanism of large scale specimens.

Advanced Constitutive Model for the Accurate Evaluation of the Structural Performance of Welded Pipes in Offshore Applications

2018 ◽  
Author(s):  
Steven Cooreman ◽  
Dennis Van Hoecke ◽  
Martin Liebeherr ◽  
Philippe Thibaux ◽  
Hervé Luccioni
Keyword(s):  
Mechanical Properties ◽  
Constitutive Model ◽  
Large Scale ◽  
Structural Integrity ◽  
Compressive Strain ◽  
Longitudinal Direction ◽  
Structural Performance ◽  
Isotropic Hardening ◽  
Hardening Models ◽  
Strain Paths

To guarantee the structural integrity of oil and gas transporting pipelines, a detailed analysis of the pipe’s structural response has to be performed. This is of particular importance for offshore applications. As large scale testing is costly and time consuming, one often relies on FE (Finite Element) modelling to accomplish, at least, part of this task. Properties that typically need to be evaluated are compressive strain capacity, collapse resistance and ovalization during reel-lay installation. Furthermore, it can be assumed that those properties are influenced by the pipe forming process, as pipe forming will change the mechanical properties and the level of anisotropy and will modify/introduce residual stresses. Therefore, a first logical step is to simulate pipe forming before evaluating the pipe’s structural performance, to account for these effects. The reliability of FE simulations largely depends on the capability of the constitutive model to accurately describe the mechanical behaviour of the material being studied. Most commercial FE codes only offer combined kinematic-isotropic hardening models. Those models cannot capture the so-called cross-hardening effect and can therefore not predict the evolution of anisotropy during pipe forming. The present paper discusses the implementation and calibration of a more advanced constitutive model, more specifically the Levkovitch-Svendsen model, which accounts for isotropic, kinematic and distortional hardening. The model was implemented in Abaqus/Implicit through a UMAT user subroutine. An inverse modelling approach was applied to calibrate the constitutive model, whereby an extensive set of mechanical tests, involving cyclic tension-compression tests and tests with changing strain paths, was conducted. To assess the model’s performance, it was used in two case studies. The first study focused on the evolution of mechanical properties during spiral pipe forming. The results show that the Levkovitch-Svendsen model allows prediction of the properties in both the transverse and longitudinal direction on pipe. When applying a kinematic-isotropic hardening law only, the properties in the longitudinal direction are significantly underestimated. In the second study, different hardening models were used to predict the evolution of ovality during reel-lay installation. It was observed that the predictions made with the Levkovitch-Svendsen model were much closer to the experimental values than the results obtained by means of a kinematic-isotropic hardening model.

Research and Development of High Strength Architectural Heavy Plates

2012 ◽  
Vol 190-191 ◽  
pp. 590-594
Author(s):  
Ming Wei Tong ◽  
Ze Xi Yuan ◽  
Kai Guang Zhang
Keyword(s):  
Low Temperature ◽  
Large Scale ◽  
High Strength ◽  
Technical Requirement ◽  
Good Match ◽  
Iron And Steel ◽  
Fracture Transition ◽  
Fine Microstructure ◽  
Low Temperature Toughness ◽  
Base Plates

This paper provides a detailed description of high strength architectural heavy plates with 80mm in thickness developed at Wuhan Iron and Steel（Group）Corporation(WISCO). The chemical composition of plates contains mainly C-Mn-Nb-V-Ti with proper content of other alloys, and the thermal-mechanical controlled process and normalizing treatment were applied. The results show that the base plates manufactured at WISCO have a good match of high strength, good through-thickness characteristic, low yield ratio and low temperature toughness with fine microstructure, and the fracture transition temperature is about -40°C. The welding plate also has high strength and good low temperature toughness which comprehensively meet the technical requirement of large-scale architectural buildings.

Effect of Quenching Temperature on Microstructures and Mechanical Properties of Boron-Nickel-Added Nb-Treated HSLA H-Beams

2011 ◽  
Vol 194-196 ◽  
pp. 165-168
Author(s):  
Wang Xiao ◽  
Zuo Cheng Wang ◽  
Xie Bin Wang ◽  
Xian Da Li ◽  
Jun Qing Gao ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Low Temperature ◽  
Charpy Impact ◽  
Charpy Impact Test ◽  
Total Elongation ◽  
Uniaxial Tensile ◽  
Uniaxial Tensile Test ◽  
Quenching Temperature ◽  
Low Temperature Toughness ◽  
Microstructures And Mechanical Properties

To lower the fracture appearance transition temperature (FATT) of Nb-treated HSLA H-beams further, boron-nickel-added Nb-treated HSLA H-beams were tempered after they were quenched at 870, 910 and 950°C respectively. Microstructures and mechanical properties, especially low temperature toughness of the experimental steels were investigated by scanning electron microscopy (SEM), uniaxial tensile test and Charpy impact test (V-notch). The results indicate that the FATTs of quenched & tempered specimens are all below -70С and that of some specimens is even below -90°С . Tensile strength of all quenched & tempered steels and their total elongation value are above 570 MPa and 21 % respectively. It can be seen that dual-phase microstructure of ferrite and tempered martensite in steels leads to the best low temperature toughness, and carbides along grain boundaries are beneficial to low temperature toughness.

scholarly journals EFFECT OF QUENCHING AND TEMPERING PROCESS ON A MEDIUM C STEEL WITH LOW CHROMIUM AND MOLYBENUM ADDITION FOR FORGED COMPONENTS

2018 ◽  
Vol 24 (2) ◽  
pp. 112 ◽  
Author(s):  
Giusepe Napoli ◽  
Giulia Fabrizi ◽  
Riccardo Rufini ◽  
Sabrina Mengaroni ◽  
Andrea Di Schino
Keyword(s):  
Mechanical Properties ◽  
Transition Temperature ◽  
Thermal Treatment ◽  
Low Temperature ◽  
Impact Test ◽  
Fracture Appearance Transition Temperature ◽  
Fracture Appearance ◽  
Temperature Application ◽  
Mn Steel ◽  
Quenching And Tempering

<p class="AMSmaintext"><span lang="EN-GB">In this paper the effect of quenching and tempering (Q&amp;T) thermal treatment on mechanical properties of a C-Mn steel with 0.22% Cr for forged components is studied. Due to the lack od any micro-alloying elements (such as vanadium or niobium) such steel can just reach mechanical target allowed by its intrinsic hardenability. Aim of this work is to evaluate the mechanical properties dependence as a function of different quenching and tempering treatments. Results show that, after Q&amp;T, steel can reach a yield strength of 330 MPa combined with a -20°C </span><span lang="EN-GB">fracture appearance transition temperature (50% FATT) measured with a Charpy-V impact test making this steel suitable for low temperature application.</span></p>

Development of 7%Ni-TMCP Steel Plate for LNG Storage Tanks

2011 ◽  
Author(s):  
Ryuichi Ando ◽  
Kazushige Arimochi ◽  
Tomoya Kawabata ◽  
Kazushi Onishi ◽  
Takahiro Kamo ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Natural Gas ◽  
Large Scale ◽  
Steel Plate ◽  
Physical And Mechanical Properties ◽  
Rare Metal ◽  
Small Scale ◽  
Chemical Compositions ◽  
Nickel Steel ◽  
Storage Tanks

Demand of natural gas continues to increase in the recent years due to the rise of environmental issue and the drastic increase of crude oil price. These events led to the increase of constructions of Liquefied Natural Gas (LNG) storage tanks worldwide. The inner tank material for above ground LNG storage tanks have mostly been made of a 9% nickel steel plate over the last 50 years as it has excellent mechanical properties under the cryogenic temperature of −160deg-C. During this period, the LNG storage tanks made of 9%Ni steel plate have been operated safely at the many LNG export and import terminals in the world. Meanwhile, technologies of steel making, refinement, design, analysis, welding and inspection have been improved significantly and enabled enlarging volumetric capacity of the tank 2–3 times. There was a tendency for nickel price to increase in recent years. In such a circumstance lowering Ni content has focused attention on the 9%Ni steel as nickel is an expensive and valuable rare metal and a 7%Ni steel plate was eventually researched and developed by optimizing the chemical compositions and applying Thermo-Mechanical Controlled Process (TMCP). As a result, it was demonstrated that 7%Ni-TMCP steel plate had excellent physical and mechanical properties equivalent to those of 9%Ni steel plate. In order to evaluate fitness of the 7%Ni-TMCP steel plate and its weld for LNG storage tanks a series of testing was conducted. Several different plate thicknesses, i.e. 6,10,25,40 and 50 mm, were chosen to run large scale fracture toughness tests including duplex ESSO tests, cruciform wide plate tests as well as small scale tests. It was concluded that the 7%Ni-TMCP steel plate warrants serious consideration for use in LNG storage tanks. This paper reports details of the research and development of the 7%Ni-TMCP steel plate.

High Strength Heavy Plate Optimised for Application in Remote Areas and Low-Temperature Service

2010 ◽  
Author(s):  
Charles Stallybrass ◽  
Joachim Konrad ◽  
Heike Meuser ◽  
Fabian Grimpe
Keyword(s):  
Mechanical Properties ◽  
Low Temperature ◽  
High Strength ◽  
Alternative Methods ◽  
Accelerated Cooling ◽  
Processing Conditions ◽  
Remote Areas ◽  
Heavy Plate ◽  
Low Temperature Toughness ◽  
Ebsd Method

The last decades have seen a steady increase in the demand for high-strength linepipe steels. These offer the most economical option to transport large gas volumes at high pressures from remote areas to the market. Since the beginning of the 1980’s, high strength heavy plates, pipes and pipe bends were developed and produced at Salzgitter Mannesmann Grobblech GmbH and EUROPIPE. Since these days, these products were steadily improved for example in terms of toughness and weldability. As gas resources in increasingly hostile environments are developed, the requirements with regard to deformability and low-temperature toughness have gained growing significance. This is a strong focus of materials development around the world. Modern high-strength heavy plates used in the production of UOE pipes are generally produced by thermomechanical rolling followed by accelerated cooling (TMCP). If accelerated cooling starts above the ferrite-austenite transformation temperature, this processing route results in a microstructure that consists predominantly of bainite. The combination of high strength and high toughness of these steels are a result of the microstructure realised by TMCP and are strongly influenced by the rolling and cooling conditions. Classical light-optical characterisation of the microstructure of these steels is at its limits because the size of the observed features is too small to allow reliable quantitative results. Therefore alternative methods have to be used to obtain a better understanding of the influence of processing conditions on the microstructure. The mechanical properties of high strength plates produced at Salzgitter Mannesmann Grobblech (MGB) and of material rolled using a laboratory rolling mill at the Salzgitter Mannesmann Forschung (SZMF) was characterised with special emphasis on low-temperature toughness. The microstructure was investigated using the electron backscatter diffraction (EBSD) method. With this method, it is possible to gain quantitative information related to features of the microstructure and relate these to the mechanical properties of the plate material. It was found that a variation of the processing conditions has a direct influence on parameters that are accessible through the EBSD method and correlates with mechanical properties. These results can be used as valuable input for the definition of the processing window for heavy plate production depending on the required plate properties.

scholarly journals Effects of Cooling Rate during Quenching and Tempering Conditions on Microstructures and Mechanical Properties of Carbon Steel Flange

Materials ◽  
2020 ◽  
Vol 13 (18) ◽  
pp. 4186 ◽  
Author(s):  
Haeju Jo ◽  
Moonseok Kang ◽  
Geon-Woo Park ◽  
Byung-Jun Kim ◽  
Chang Yong Choi ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Low Temperature ◽  
Cooling Rate ◽  
Charpy Impact ◽  
Hardness Test ◽  
Finite Element Method Simulation ◽  
Secondary Phases ◽  
Practical Applications ◽  
Low Temperature Toughness ◽  
Microstructures And Mechanical Properties

This study investigated the mechanical properties of steel in flanges, with the goal of obtaining high strength and high toughness. Quenching was applied alone or in combination with tempering at one of nine combinations of three temperatures TTEM and durations tTEM. Cooling rates at various flange locations during quenching were first estimated using finite element method simulation, and the three locations were selected for mechanical testing in terms of cooling rate. Microstructures of specimens were observed at each condition. Tensile test and hardness test were performed at room temperature, and a Charpy impact test was performed at −46 °C. All specimens had a multiphase microstructure composed of matrix and secondary phases, which decomposed under the various tempering conditions. Decrease in cooling rate (CR) during quenching caused reduction in hardness and strength but did not affect low-temperature toughness significantly. After tempering, hardness and strength were reduced and low-temperature toughness was increased. Microstructures and mechanical properties under the various tempering conditions and CRs during quenching were discussed. This work was based on the properties directly obtained from flanges under industrial processes and is thus expected to be useful for practical applications.

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