Favourable Steel Structures using High Strength Steels

ce/papers ◽  
2021 ◽  
Vol 4 (2-4) ◽  
pp. 1530-1536
Author(s):  
Fengyan Gong ◽  
André Dürr ◽  
Jochen Bartenbach
Keyword(s):  
High Strength Steels ◽  
Steel Structures ◽  
High Strength

Influence of Predetermined Surface Defect to the Bendability of Ultra-High-Strength Steel

2012 ◽  
Vol 504-506 ◽  
pp. 901-906 ◽  
Author(s):  
Antti Määttä ◽  
Antti Järvenpää ◽  
Matias Jaskari ◽  
Kari Mäntyjärvi ◽  
Jussi A. Karjalainen
Keyword(s):  
Surface Defects ◽  
High Strength Steels ◽  
Steel Structures ◽  
High Strength ◽  
Crack Size ◽  
Critical Crack ◽  
Bending Radius ◽  
Ultra High Strength Steels ◽  
Materials Used ◽  
Critical Crack Size

The use of ultra-high-strength steels (UHS) has become more and more popular within last decade. Higher strength levels provide lighter and more robust steel structures, but UHS-steels are also more sensitive to surface defects (e.g. scratches). Practically this means that the critical crack size decreases when the strength increases. The aim of the study was to study if the formula of critical crack size is valid on forming processes of UHS-steels. Surface cracks with different depths were created by scratching the surface of the sheet by machining center. Effect of the scratch depth was determined by bending the specimens to 90 degrees. Bents were then visually compared and classified by the minimum achieved bending radius. Test materials used were direct quenched (DQ) bainitic-martensitic UHS steels (YS/TS 960/1000 and 1100/1250). Results from the bending tests were compared to the calculated values given by the formula of critical crack size.

Calculation of Fatigue Capacity for a Subsea Wellhead Connector

2020 ◽  
Author(s):  
Seyed H. Hashemizadeh ◽  
Venu Sunkavilli ◽  
Torfinn Hørte ◽  
Per Osen
Keyword(s):  
Fatigue Life ◽  
Hot Spot ◽  
High Strength Steels ◽  
Steel Structures ◽  
High Strength ◽  
Element Model ◽  
Fe Model ◽  
Specific Advice ◽  
Drilling Operations ◽  
Set Up

Abstract In the 2019 version of DNVGL-RP-C203 Fatigue Design of Offshore Steel Structures, significantly improved methods have been added on how to establish M-N curves representing the fatigue resistance of preloaded connectors subject to cyclic bending. The M-N curve parameters are typically provided by the manufacturer and used by operators and drilling contractors for calculating the wellhead fatigue life for planned drilling operations. DNVGL-RP-C203 provides specific advice on how to establish design M-N curves based on analysis, and the augmentation by possible testing, where testing may grant more favorable M-N curves and thus extended fatigue life for any given case. The paper provides background and introduction to the improved analysis methodology and relevant S-N curves for high-strength steels for wellhead systems, given in the 2019 version of the DNVGL-RP-C203. It includes a worked example in order to demonstrate the detailed use of the method, applied on a Baker Hughes preloaded BOP connector, connected to a 27” wellhead mandrel. This example describes the finite element model set up, FE model mesh refinement in hot-spots, the application of cyclic loads, extraction of hot-spot cyclic stresses, and the establishment of the M-N curve for the connector.

scholarly journals Overview on the digitized production of welded steel structures

2022 ◽  
Author(s):  
Tuomas Skriko ◽  
Antti Ahola ◽  
Timo Björk
Keyword(s):  
High Strength Steels ◽  
Steel Structures ◽  
High Strength ◽  
Production Quality ◽  
Robotic Welding ◽  
Human Errors ◽  
Welded Steel ◽  
Short Run ◽  
Ultra High Strength Steels ◽  
Cost Efficient

Abstract This paper presents a concept and practical topics involved in digitized production. The term “production” denotes the design, fabrication, and service life of a product, which in this case elaborates on welded steel structures. This includes the required information for guiding all the process stages of the chosen material back to its re-melting, following the material flow in a fully digitized form. This concept enables an increase in production quality at a higher level while minimizing the risk of human errors. Automation of the short-run production of steel structures for demanding applications is also a key goal, together with securing a cost-efficient process. Typically, such structures are fabricated from high- or ultra-high-strength steels. Though challenging, reaching these aims seems to be realistic by applying advanced fatigue design methods, using high-quality robotic welding and receiving information about the real loading of the structure.

scholarly journals IMPLEMENTATION OF LONGITUDINAL WELDING STRESSES INTO STRUCTURAL CALCULATION OF STEEL STRUCTURES

2015 ◽  
Vol 22 (1) ◽  
pp. 47-55 ◽  
Author(s):  
Hartmut Pasternak ◽  
Gabriel Kubieniec
Keyword(s):  
Numerical Simulation ◽  
Residual Stress ◽  
Cross Sections ◽  
High Strength Steels ◽  
Evaluation Process ◽  
Steel Structures ◽  
High Strength ◽  
Experimental Models ◽  
Structural Calculation ◽  
The Difference

During welding of typical steel cross sections, like T or I- Profiles e.g., residual stress occurs and need to be considered during the design process. With knowledge of the stress state after welding, farther calculation with different models are carried out. The systematic study will show three steps of the Okerblom's model to consider in the evaluation process of the welding stresses. The results of the numerical simulation and experimental models are show and compared. With that, the difference between the buckling curve from EN 1993-1-1 (2006) and the study are shown for steel S235 and S460. Especially for the high strength steels, the nowadays design conditions are very conservative and further investigation is needed and recommended.

scholarly journals Hydrogen in Aluminium-Coated Steels Exposed to Synthetic Seawater

Surfaces ◽  
2020 ◽  
Vol 3 (3) ◽  
pp. 282-300 ◽  
Author(s):  
Shiladitya Paul
Keyword(s):  
Open Circuit Potential ◽  
High Strength Steels ◽  
Steel Structures ◽  
High Strength ◽  
Open Circuit ◽  
Coated Steel ◽  
Synthetic Seawater ◽  
Uncoated Steel ◽  
Thermally Sprayed ◽  
Sacrificial Protection

Thermally sprayed aluminium (TSA) coatings provide protection to offshore steel structures without the use of external cathodic protection (CP) systems. These coatings provide sacrificial protection in the same way as a galvanic anode, and thus hydrogen embrittlement (HE) becomes a major concern with the use of high strength steels. The effect of TSA on the HE of steel seems to remain largely unknown. Further, the location of hydrogen in TSA-coated steel has not been explored. To address the above knowledge gap, API 5L X80 and AISI 4137 steel coupons, with and without TSA, were prepared and the amount of hydrogen present in these steels when cathodically polarised to −1.1 V (Ag/AgCl) for 30 days in synthetic seawater was determined. One set of TSA-coated specimens was left at open circuit potential (OCP). The study indicates that the amount of hydrogen present in TSA-coated steel is ~100 times more than the amount found in uncoated steel, and that the hydrogen seems to be largely localised in the TSA layer.

scholarly journals EVALUATION OF EFFECTIVITY OF HIGH-STRENGTH STEELS AND SEISMIC PERFORMANCE FOR LOW- AND MEDIUM-RISE PASSIVE CONTROL STEEL STRUCTURES

2016 ◽  
Vol 22 (52) ◽  
pp. 909-914
Author(s):  
Yasunari WATANABE ◽  
Toshiaki SATO ◽  
Haruyuki KITAMURA ◽  
Daiki SATO ◽  
Kazuaki MIYAGAWA ◽  
...  
Keyword(s):  
Seismic Performance ◽  
Passive Control ◽  
High Strength Steels ◽  
Steel Structures ◽  
High Strength

Failure Modes and Rules Related to the Yield-to-Tensile Strength Ratio in Steel Structures

2021 ◽  
Author(s):  
Wei Jun Wong ◽  
Carey L. Walters
Keyword(s):  
Tensile Strength ◽  
Failure Modes ◽  
High Strength Steels ◽  
Steel Structures ◽  
High Strength ◽  
Future Research ◽  
Engineering Practice ◽  
Stress Concentrations ◽  
Fracture Elongation ◽  
Design Yield

Abstract Upper limits on the ratio of the yield strength to the tensile strength (σy/σu ratio) and lower limits on the fracture elongation εf are present in various offshore, maritime and civil engineering rules, standards and specifications for steel structures as a provision for the minimum material ductility and toughness which ensures sufficient structural ductility. In other instances, the design yield stress to be adopted in strength calculations is reduced from its nominal value if the σy/σu ratio exceeds a certain limit. Such requirements deter the use of high strength steels (nominal σy higher than 690 MPa), which inherently have a high σy/σu ratio. To guide subsequent efforts towards optimised and scientifically grounded σy/σu limits and wider application of high strength steels, this paper first presents an overview of the current provisions in engineering practice relating to the σy/σu ratio and structural ductility, and it then discusses the key underlying failure mechanisms to which these ductility requirements are relevant: tensile strain localization, yielding and localization precipitated by stress concentrations, localization of plastic bending hinges and ductile fracture. The reasoning behind the current provisions, the findings of previous research concerning the requirements, and the key potential areas for future research are highlighted.

scholarly journals MAIN DIRECTIONS OF MODERN DEVELOPMENT OF STEEL CONSTRUCTIONS FOR BUILDINGS AND STRUCTURES

2021 ◽  
pp. 5-12
Author(s):  
Bilyk S.І. ◽  
◽  
Bilyk А.S. ◽  
Keyword(s):  
High Strength Steels ◽  
Steel Structures ◽  
High Strength ◽  
Structural Systems ◽  
Metal Structures ◽  
Term Operation ◽  
Design Solutions ◽  
The Creation ◽  
Welding Processes

The development of technologies for the manufacture and design of steel structures, together with the development of computer technologies, makes it possible to increase productivity in the building industry. The analysis and generalization of such factors made it possible to identify the main trends and directions of the creation and improvement of metal structures, taking into account the automation of their manufacturing processes and the use of BIM technologies. The highlighted tendencies make it possible to show both new directions for the development of scientific research and directions for the development of practical methodologies for determining the regularities of the stress-strain state of structural systems using steel. Among the main trends, the following are highlighted: digitalization of the metal construction industry; automation and robotization of the manufacturing and assembling processes; science intensity of design and production processes; greening production, evaluating design solutions from the standpoint of environmental safety; complex optimization of design solutions. The authors highlight the next important tasks and prospects for the development of the creation of effective metal structures: the creation and use of high-strength steels C960 and more, the improvement of automated and robotic welding processes for ultra-high-strength steels with various metal thicknesses; development and improvement of the theory of calculation of thin-walled and composite structures, determination of the actual resource of metal structures after long-term operation; introduction into the practice of creating new structures of rational and optimal design approaches with the requirements of long-term operation and life cycle, including progressive collapse, reduction in the cost of fire and anti-corrosion covers for steel structures; improvement of building codes and rules for the design of metal structures; implementation of leading foreign standards and experience; training of modern professional engineers and technicians; development of experimental and theoretical studies of full-scale samples of structures on the basis of creating high-precision information models of structural systems.

scholarly journals Characterization of bainite-ferrite structures formed on the heat-affected zone of a dissimilar welds of high-strength steel (S700MC/S960QC) and their dependency on cooling time

2020 ◽  
Vol 65 (4) ◽  
pp. 159-172
Author(s):  
Bayock Njock ◽  
Paul Kah ◽  
Belinga Mvola ◽  
Pavel Layus ◽  
Xiaoyu Cai
Keyword(s):  
Heat Affected Zone ◽  
Volume Fraction ◽  
High Strength Steels ◽  
Steel Structures ◽  
High Strength ◽  
Cooling Time ◽  
Granular Bainite ◽  
High Yield ◽  
Dissimilar Welding

Modern steel structures and joints must satisfy various increasingly demanding requirements such as high yield strength, improved cross section to mass ratio, and desirable ductile-to-brittle transition properties. Consequently, joining different types of high-strength steels has become an attractive option from the cost perspective and for weight and corrosion reduction. In dissimilar welding, however, there remains a need for better understanding of discrepancies in microstructure formation resulting from asymmetric heat distribution. In this study, a characterization of the transformation of bainite, ferrite, and martensite in the microstructure of the heat affected zone (HAZ) formed by a cooling time of 10 kJ/cm of heat input was carried out for dissimilar high-strength joint steels (S700MC/S960QC). The characterization was performed by scan electron microscopy (SEM) sampling, the images of which were analyzed by ImageJ Pro and evaluated by volume fraction of block - like granular bainite (GB). The alloy elements composition close to the fusion line of both materials was then assessed using energy dispersive X-ray spectroscopy (EDS). The results showed a strong presence of GB, which had about 70% volume fraction in S700MC at 615 °C, and which comprised formations of lower bainite and retained austenite (RA) at 420 °C. The presence of 55% block GB was observed at 470 °C in S960QC, which was caused by the formation of tempered martensite (TMA) at 400 °C. Presence of 1.3Ni, 0.4Mo, and 1.6Mn in the coarse grain heat affected zone (CGHAZ) of S700MC confirmed the risk of brittle failure on the S700MC side due to the high presence of carbide and ferrite in the GB.

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