Evaluation of Structural Steel Castings for the Hutton Tension Leg Platform

1984 ◽  
Vol 106 (2) ◽  
pp. 234-239
Author(s):  
N. Ellis ◽  
M. M. Salama ◽  
D. V. Beggs
Keyword(s):  
Mechanical Properties ◽  
Chemical Composition ◽  
Plate Steel ◽  
Structural Elements ◽  
Tension Leg Platform ◽  
Weld Repair ◽  
Testing Program ◽  
Steel Castings ◽  
Novel Concept ◽  
Welding Procedure

The use of steel castings as major structural elements of the Hutton tension leg platform represents a relatively novel concept. In order to ensure that these castings would provide adequate service, an extensive testing program was undertaken to assess variations in chemical composition and mechanical properties of prototype castings. In addition, a rigorous acceptance procedure for production castings was developed. The results of these programs showed that steel castings possessed adequate strength and toughness. Also, a welding procedure was developed which consistently produced sound weld repair and satisfactory joints between cast and plate steel.

Weld Repair of Shell Plates During Seagoing Operations

2002 ◽  
Author(s):  
Per R. M. Lindstro¨m ◽  
Anders Ulfvarson
Keyword(s):  
Grain Size ◽  
Theoretical Model ◽  
Chemical Composition ◽  
Cooling Rate ◽  
Base Material ◽  
Forced Flow ◽  
Welding Parameters ◽  
Weld Repair ◽  
Welding Seam ◽  
Welding Procedure

An algorithm to estimate the cooling rate of welding seams on the shell plating of a ship, below the waterline, while it is on voyage has been derived. The demand for this technique has arisen from the wish of ship operators to make it possible for the safe repair of ship structures without taking them out of operation. [1] The strength of the shell plating after welding is determined by its metallurgic structure, which is dependent on the cooling rate, its chemical composition and the original grain size of the base material. [2] The cooling rate for this type of welding seam depends on the velocity of the water flow, the distance from the bow, the thickness of the plate, and the heat from the heat input of the welding. The algorithm makes it possible to calculate the cooling rate for a base material affected by a forced flow of fluid by means of Rosenthal’s equation and thus enabling suitable welding parameters to be determined. As the welding parameters can be chosen to fit the specific repair to be made, it is now possible to determine the suitability of a welding procedure in advance. The algorithm is applicable when determining welding parameters at Hot-Tapping operations as well, where the base material is affected by a forced flow of fluid. A number of experiments have been performed and the results support the theoretical model. The research project continues with the aim of finding an algorithm to include the enhanced cooling rate due to the layer of boiling fluid on the back of the base material. A method to improve the measurements of the most important parameter in the algorithm has been developed and makes it possible to build up a quantitative database of typical values for various configurations.

scholarly journals Mathematical model of forecast of strength of low carbon steel

2021 ◽  
pp. 49-58
Author(s):  
D.S. Kotenko
Keyword(s):  
Mechanical Properties ◽  
Regression Analysis ◽  
Chemical Composition ◽  
Yield Strength ◽  
Alloy Steel ◽  
The State ◽  
Structural Elements ◽  
Low Carbon ◽  
Low Alloy Steel ◽  
Short Period

Introduction. The use of different mathematical approaches to assessing and forecasting the quality characteristics of materials for different purposes is always relevant. The urgency of solving problems and problems of modern materials science with the use of methods of mathematical modeling allows to optimize technological processes of production, to determine in a short period of time the set parameters with minimal time and material costs. In the work using the method of regression analysis, the strength criteria of low-carbon low-alloy steel depending on the characteristics of the structure were evaluated. Materials and methods. Samples of Ст3пс steel grade made of a circle with a diameter of 24 mm were selected as the material for the study. The structure and mechanical properties were investigated at three reference points: at a distance of 0 mm from the center of the sample, 6 mm from the center of the sample and 12 mm from the center of the sample. The steel was investigated in the state of factory delivery, and after two modes of heat treatment to obtain ferritic-perlite and bainite structure. The following properties were determined: microhardness, tensile strength and yield strength, hardness and toughness at room temperature. The results of the experiment. Models for estimating mechanical properties were obtained using regression analysis. Models describing the relationship between the microhardness of pearlite and its area (R2 = 0.8366) in the state of factory delivery have a relatively high correlation coefficient; the score and the ultimate strength (R2 = 1.0) and yield strength (R2 = 0.8669) of steel after cooling in an oil medium; hardness and area of pearlite after hardening steel in the pearlite region (R2 = 0.7215). Conclusions. The practical significance of the work performed is the ability to perform a rapid analysis of the properties of rolled metal from steel Ст3пс based on determining the area of the structural elements and their scoring. However, it should be noted that the existing discrepancy between the results of the experiment and the forecast using the obtained models may be due to the influence of other factors. Such factors include the influence of chemical composition, incompleteness of formal axiomatics, which occurs when estimating the geometry of complex structural elements. Keywords: low-alloy steel; structure; chemical composition; mechanical properties; regression model; properties forecast

scholarly journals Welding procedure research of titanium heat exchangers

2021 ◽  
Vol 261 ◽  
pp. 02002
Author(s):  
Chengjuni Jiang ◽  
Wei Wang ◽  
Qian Li ◽  
Xiaoli Zhang
Keyword(s):  
Mechanical Properties ◽  
Chemical Composition ◽  
Heat Exchangers ◽  
Visual Inspection ◽  
Ideal Structure ◽  
Dimensional Inspection ◽  
Weld Structure ◽  
Titanium Tube ◽  
Mechanical Properties And Corrosion ◽  
Welding Procedure

In order to manufacture Gr.1 titanium heat exchangers, the welding property and weld structure of titanium tube-to-tubesheet are analyzed. The procedure of Pulse GTAW is used and the visual inspection, dimensional inspection, chemical composition, mechanical properties and metallographic structures are tested and analyzed. The results show that the weld joint can get ideal structure and good chemical composition, mechanical properties and corrosion resistance. The successful welding qualification has accumulated valuable experience for manufacture of titanium heat exchangers.

Study of the character and causes of destruction of the cardan shaft of the propeller engine

2019 ◽  
Vol 85 (12) ◽  
pp. 43-50
Author(s):  
D. A. Movenko ◽  
L. V. Morozova ◽  
S. V. Shurtakov
Keyword(s):  
Mechanical Properties ◽  
Chemical Composition ◽  
Yield Point ◽  
Protective Coating ◽  
Fracture Pattern ◽  
Corrosion Cracking ◽  
Tempered Martensite ◽  
Neck Formation ◽  
Static Mechanism ◽  
Shaft Surface

The results of studying operational destruction of a high-loaded cardan shaft of the propeller engine made of steel 38KhN3MFA are presented to elucidate the cause of damage and develop a set of recommendations and measures aimed at elimination of adverse factors. Methods of scanning electron and optical microscopy, as well as X-ray spectral microanalysis are used to determine the mechanical properties, chemical composition, microstructure, and fracture pattern of cardan shaft fragments. It is shown that the mechanical properties and chemical composition of the material correspond to the requirements of the regulatory documentation, defects of metallurgical origin both in the shaft metal and in the fractures are absent. The microstructure of the studied shaft fragments is tempered martensite. Fractographic analysis revealed that the destruction of cardan shaft occurred by a static mechanism. The fracture surface is coated with corrosion products. The revealed cracks developed by the mechanism of corrosion cracking due to violation of the protective coating on the shaft. The results of the study showed that the destruction of the cardan shaft of a propeller engine made of steel 38Kh3MFA occurred due to formation and development of spiral cracks by the mechanism of stress corrosion cracking under loads below the yield point of steel. The reason for «neck» formation upon destruction of the shaft fragment is attributed to the yield point of steel attained during operation. Regular preventive inspections are recommended to assess the safety of the protective coating on the shaft surface to exclude formation and development of corrosion cracks.

Structural features and strength behavior of TRIP/TWIP steels

2020 ◽  
pp. 5-18
Author(s):  
D. V. Prosvirnin ◽  
◽  
M. S. Larionov ◽  
S. V. Pivovarchik ◽  
A. G. Kolmakov ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Chemical Composition ◽  
Thermomechanical Processing ◽  
Maximum Load ◽  
Structural Features ◽  
Stacking Fault ◽  
Stacking Fault Energy ◽  
Structural And Functional Properties ◽  
Twip Steels ◽  
The Creation

A review of the literature data on the structural features of TRIP / TWIP steels, their relationship with mechanical properties and the relationship of strength parameters under static and cyclic loading was carried out. It is shown that the level of mechanical properties of such steels is determined by the chemical composition and processing technology (thermal and thermomechanical processing, hot and cold pressure treatment), aimed at achieving a favorable phase composition. At the atomic level, the most important factor is stacking fault energy, the level of which will be decisive in the formation of austenite twins and / or the formation of strain martensite. By selecting the chemical composition, it is possible to set the stacking fault energy corresponding to the necessary mechanical characteristics. In the case of cyclic loads, an important role is played by the strain rate and the maximum load during testing. So at high loading rates and a load approaching the yield strength under tension, the intensity of the twinning processes and the formation of martensite increases. It is shown that one of the relevant ways to further increase of the structural and functional properties of TRIP and TWIP steels is the creation of composite materials on their basis. At present, surface modification and coating, especially by ion-vacuum methods, can be considered the most promising direction for the creation of such composites.

Weldability - Behavior of Welded Reinforcement

2019 ◽  
Vol 70 (10) ◽  
pp. 3469-3472
Keyword(s):  
Mechanical Properties ◽  
Chemical Composition ◽  
Mechanical Characteristics ◽  
Mechanical Performance ◽  
Current Work ◽  
Carbon Equivalent ◽  
Work Process ◽  
Ultimate Limit

Weldability involves two aspects: welding behavior of components and safety in operation. The two aspects will be reduced to the mechanical characteristics of the elements and to the chemical composition. In the case of steel reinforcing rebar’s, it is reduces to the percentage of Cech(carbon equivalent) and to the mechanical characteristics: the yielding limit, the ultimate limit, and the elongations which after that represent the ductility class in which the re-bars is framed. The paper will present some types of steel reinforcing rebar’s with its mechanical characteristics and the welding behavior of those elements. In the current work, process-related behavior of welded reinforcement, joint local and global mechanical properties, and their correlation with behavior of normal reinforcement and also the mechanical performance resulted in this type of joints. Keywords: welding behavior, ultimate limit, reinforcing rebar’s

scholarly journals Cellular Orientation on Repeatedly Stretching Gelatin Hydrogels with Supramolecular Cross-Linkers

Polymers ◽  
2019 ◽  
Vol 11 (12) ◽  
pp. 2095
Author(s):  
Dae Hoon Lee ◽  
Yoshinori Arisaka ◽  
Asato Tonegawa ◽  
Tae Woong Kang ◽  
Atsushi Tamura ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Chemical Composition ◽  
Cellular Response ◽  
Linear Polymer ◽  
Cross Linking ◽  
Adherent Cells ◽  
Cell Cultivation ◽  
Supramolecular Compound ◽  
Synthetic Materials ◽  
Cyclic Molecules

The cytocompatibility of biological and synthetic materials is an important issue for biomaterials. Gelatin hydrogels are used as biomaterials because of their biodegradability. We have previously reported that the mechanical properties of gelatin hydrogels are improved by cross-linking with polyrotaxanes, a supramolecular compound composed of many cyclic molecules threaded with a linear polymer. In this study, the ability of gelatin hydrogels cross-linked by polyrotaxanes (polyrotaxane–gelatin hydrogels) for cell cultivation was investigated. Because the amount of polyrotaxanes used for gelatin fabrication is very small, the chemical composition was barely altered. The structure and wettability of these hydrogels are also the same as those of conventional hydrogels. Fibroblasts adhered on polyrotaxane–gelatin hydrogels and conventional hydrogels without any reduction or apoptosis of adherent cells. From these results, the polyrotaxane–gelatin hydrogels have the potential to improve the mechanical properties of gelatin without affecting cytocompatibility. Interestingly, when cells were cultured on polyrotaxane–gelatin hydrogels after repeated stress deformation, the cells were spontaneously oriented to the stretching direction. This cellular response was not observed on conventional hydrogels. These results suggest that the use of a polyrotaxane cross-linking agent can not only improve the strength of hydrogels but can also contribute to controlling reorientation of the gelatin.

scholarly journals Controlled atmosphere GMAW welding of transportation vehicles and production machines parts made from 30MnB5 steel

2018 ◽  
Vol 216 ◽  
pp. 03001 ◽  
Author(s):  
Evgeny Ivanayskiy ◽  
Aleksei Ishkov ◽  
Aleksandr Ivanayskiy ◽  
Iakov Ochakovskii
Keyword(s):  
Mechanical Properties ◽  
Carbon Dioxide ◽  
Carbon Monoxide ◽  
Chemical Composition ◽  
Controlled Atmosphere ◽  
Shielding Gas ◽  
Reducing Atmosphere ◽  
Metal Composition ◽  
Gmaw Welding ◽  
Welding Materials

The paper studies the influence of shielding gas on the composition and the structure of weld joint metal of 30MnB5 steel applied in essential parts of automobiles and tractors. The welding was performed in inert, oxidizing and reducing atmospheres. It was established that TIG welding with argon used as shielding gas did not provide the required mechanical properties when using conventional welding materials. Carbon dioxide during MAG welding caused partial burning of alloying elements. Carbon monoxide used as shielding gas was proved to form reducing atmosphere enabling to obtain chemical composition close to the base metal composition. Metallographic examinations were carried out. The obtained results provided full-strength weld, as well as the required reliability and durability of welded components and joints.

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