Mid Thickness Delayed Cracking of Z-Quality Offshore Steel

2011 ◽  
Author(s):  
Stig Gra˚berg ◽  
Lars Volden ◽  
Anthonius Johannes Paauw
Keyword(s):  
Thick Plate ◽  
Phosphorus Content ◽  
Manganese Sulfide ◽  
Steel Structure ◽  
Casting Process ◽  
Tensile Specimen ◽  
Material Behavior ◽  
Centre Line ◽  
Delayed Cracking ◽  
Ductile Behavior

During fabrication of a steel structure for an offshore modification project, delayed cracking was experienced in the mid plane or centre line of a 30 mm thick plate. The plate was part of a restraint box frame where 25 mm plates were welded to this 30 mm plate on both plate-surfaces. The applied 30 mm plate was a higher strength offshore steel (EN10225-S420 G2+M), with special through thickness properties and enhanced chemical composition as defined in material data sheet MDS Y30 of NORSOK M-120. Fracture mechanical testing including KV and CTOD in the mid plane confirmed that a very low toughness was present here with a brittle fracture type (cleavage). The plate was manufactured by the continuous casting process which due to centre line segregation resulted in high levels of manganese sulfide inclusions but also niobium carbides/nitrides. The plate manufacturer considered the documented toughness level as expected. Similar testing was performed on a 30 mm plate also delivered to the same material specification but of which the material certificate revealed a 10 times lower sulfur and phosphorus content indicating a much higher steel refinement. A significant higher toughness was obtained for this steel with high ductile behavior. Both steels showed a similar through thickness ductility, measured elongation for the through thickness tensile specimen, which implies that this property does not guaranty for the observed material behavior.

scholarly journals Fiducial marker application method for position alignment of in situ multimodal X-ray experiments and reconstructions

2016 ◽  
Vol 49 (2) ◽  
pp. 700-704 ◽  
Author(s):  
Paul A. Shade ◽  
David B. Menasche ◽  
Joel V. Bernier ◽  
Peter Kenesei ◽  
Jun-Sang Park ◽  
...  
Keyword(s):  
Focused Ion Beam ◽  
Ion Beam ◽  
Tensile Specimen ◽  
Material Behavior ◽  
Validation Data ◽  
Great Opportunity ◽  
Characterization Methods ◽  
X Ray ◽  
Multiple Data Sets

An evolving suite of X-ray characterization methods are presently available to the materials community, providing a great opportunity to gain new insight into material behavior and provide critical validation data for materials models. Two critical and related issues are sample repositioning during an in situ experiment and registration of multiple data sets after the experiment. To address these issues, a method is described which utilizes a focused ion-beam scanning electron microscope equipped with a micromanipulator to apply gold fiducial markers to samples for X-ray measurements. The method is demonstrated with a synchrotron X-ray experiment involving in situ loading of a titanium alloy tensile specimen.

The Influence of Small Defects on Tensile Specimen Ductility and Symmetry of Deformation

1988 ◽  
Vol 110 (3) ◽  
pp. 224-233 ◽  
Author(s):  
P. Matic ◽  
M. I. Jolles
Keyword(s):  
Structural Integrity ◽  
Tensile Specimen ◽  
Material Behavior ◽  
Necessary Condition ◽  
Geometric Imperfection ◽  
Void Defect ◽  
Weld Material ◽  
Specimen Axis ◽  
Fabrication Defects ◽  
Reduction Of Area

The quantitative translation of physical weld quality into structural integrity prediction depends on accurate characterization of weld material behavior in the presence of fabrication defects. The presence of such defects will, however, significantly influence the response of common material test specimens. If the influence of such defects is fully understood, test specimen data may be interpreted in a more meaningful way. The role of a physically relevant geometric imperfection, in the form of a spherical void defect, on cylindrical tensile specimen response is computationally simulated for HY-100 weld metal. Defect radius and location along the specimen axis are treated as independent parameters. Asymmetry of specimen deformation (in terms of specimen neck location) and specimen ductility (in terms of the reduction of area at failure) are computationally predicted. Results suggest that the neck location does not necessarily coincide with the defect location. Therefore, geometric defects are a sufficient condition for asymmetry of neck location but not a necessary condition for neck formation. In addition, coincidence of the defect and the neck reduces the specimen ductility at failure to a minimum value which depends on defect size. When the defect and neck are separated, the defect free specimen ductility at failure, i.e., the maximum ductility value, is recovered as an upper bound. The transition between these two ductility values is abrupt, despite the continuous nature of the physical problem. Preliminary implications of these results on the assessment of defect criticality are discussed.

Comparison between Manufacturing Processes of Fiber-Reinforced Cement-Based Panels (FRCBPs)

2012 ◽  
Vol 253-255 ◽  
pp. 503-507
Author(s):  
Bang Yeon Lee ◽  
Yun Yong Kim ◽  
Jin Wook Bang ◽  
Woo Jung Chung ◽  
Dong Su Joung ◽  
...  
Keyword(s):  
Influencing Factor ◽  
Casting Process ◽  
Extrusion Process ◽  
Manufacturing Processes ◽  
Test Results ◽  
Fiber Reinforced ◽  
Reinforced Cement ◽  
Strength And Stiffness ◽  
Flexural Tests ◽  
Ductile Behavior

The manufacturing process is a significant influencing factor on the mechanical properties of fiber-reinforced cement-based composites. This paper presents the investigation of the effects of the manufacturing processes on the properties of fiber-reinforced cement-based panels (FRCBPs). Two types of FRCBPs were manufactured using a casting process (FRCBP-C) and an extrusion process (FRCBP-E), and then their bending properties were evaluated using flexural tests. The test results demonstrated that the strength and stiffness of the FRCBP-C specimens were lower than that of the FRCBP-E specimens. However, the FRCBP-C specimens exhibited more ductile behavior than the FRCBP-E specimens.

scholarly journals The Effect of Different Braced Configurations on the Nonlinear Seismic Behavior of Steel Structure

2019 ◽  
Vol 1 (1) ◽  
pp. 22-28
Author(s):  
Mehmet Fatih YILMAZ
Keyword(s):  
Construction Material ◽  
Pushover Analysis ◽  
Steel Structure ◽  
Material Model ◽  
Material Behavior ◽  
Deformation Capacity ◽  
Structural Components ◽  
Braced Frame ◽  
Frame Element ◽  
Steel Construction

Improvements in construction technologies have allowed steel structural elements to become more frequently used today in order to enable different architectural designs and to meet structural performance more effectively and efficiently. Structural steel has been used for more than a hundred years and has been tested under real earthquakes, which provide the basis of many earthquake-resistant steel construction standards. The major advantage of steel construction material is that it allows for large plastic deformations. Structural deformations vary depending on the deformation capacity of the structural components in addition to the configuration of the structural components. In this study, moment resisting frames (MRF), X braced frame (XBF), Inverse V braced frame (IVBF), K braced frame (KBF), and eccentric inverse V braced frames (EIVBF) were used to examine the effect of different steel braced systems on the plastic deformation capacity of steel structure with the help of nonlinear static pushover analysis. Bilinear material model was utilized to represent nonlinear steel material behavior and inelastic displacement-based frame element were used to represent column and beam element. The analyses' results demonstrated that the braced frame configuration had a significant effect on the lateral response of steel frame structures.

scholarly journals Mechanical Properties Characterization of Welded Automotive Steels

Metals ◽  
2019 ◽  
Vol 10 (1) ◽  
pp. 1 ◽  
Author(s):  
Ehsan Javaheri ◽  
Janot Lubritz ◽  
Benjamin Graf ◽  
Michael Rethmeier
Keyword(s):  
Mechanical Properties ◽  
Laser Beam ◽  
Automobile Industry ◽  
Laser Beam Welding ◽  
Steel Structures ◽  
Material Model ◽  
Tensile Specimen ◽  
Material Behavior ◽  
Resistance Spot ◽  
Indentation Tests

Among the various welding technologies, resistance spot welding (RSW) and laser beam welding (LBW) play a significant role as joining methods for the automobile industry. The application of RSW and LBW for the automotive body alters the microstructure in the welded areas. It is necessary to identify the mechanical properties of the welded material to be able to make a reliable statement about the material behavior and the strength of welded components. This study develops a method by which to determine the mechanical properties for the weldment of RSW and LBW for two dual phase (DP) steels, DP600 and DP1000, which are commonly used for the automotive bodies. The mechanical properties of the resistance spot weldment were obtained by performing tensile tests on the notched tensile specimen to cause an elongation of the notched and welded area in order to investigate its properties. In order to determine the mechanical properties of the laser beam weldment, indentation tests were performed on the welded material to calculate its force-penetration depth-curve. Inverse numerical simulation was used to simulate the indentation tests to determine and verify the parameters of a nonlinear isotropic material model for the weldment of LBW. Furthermore, using this method, the parameters for the material model of RSW were verified. The material parameters and microstructure of the weldment of RSW and LBW are compared and discussed. The results show that the novel method introduced in this work is a valid approach to determine the mechanical properties of welded high-strength steel structures. In addition, it can be seen that LBW and RSW lead to a reduction in ductility and an increase in the amount of yield and tensile strength of both DP600 and DP1000.

Numerical Simulation and Experiment Research on Thick Plate Multi-Point Forming Process with Elastic Cushion

2011 ◽  
Vol 704-705 ◽  
pp. 102-108 ◽  
Author(s):  
Li Yong Wang ◽  
Le Li
Keyword(s):  
Numerical Simulation ◽  
Flexible Manufacturing ◽  
Thick Plate ◽  
Surface Defects ◽  
Yield Criterion ◽  
Material Behavior ◽  
Forming Process ◽  
Workpiece Material ◽  
Explicit Finite Element ◽  
Elastic Cushion

Multi-point forming (MPF) is an advanced flexible manufacturing technology for three-dimensional sheet metal forming. The substance of MPF is replacing the conventional solid dies by a set of discrete punches called ‘‘punch group’’. Because the reconfigurable discrete punches are used, part manufacturing costs are reduced and manufacturing time is shortened. However due to the discrete contacts between the workpiece and punches, the dimple defects occurred, which are inevitable and particular for MPF. For thick plate, the surface defect is the mainly dimple defect during its MPF process. In this study, elastic cushion was proposed to prevent these surface defects. The dynamic explicit finite element method was chosen to implement the simulation of MPF process. The Hill’s anisotropic yield criterion was used to describe the workpiece material behavior, and the elastic cushion was described with using the hyperelastic material model. The method to determine each punch position to construct forming surface was introduced. The MPF process with and without using elastic cushion was simulated to study the effect of the elastic cushion on preventing the surface defects. The relevant experiment was implemented, and it verified that the elastic cushion is effective method to suppress the surface defects during the thick plate MPF process. Keyword: flexible forming process (FFP), elastic cushion, surface defects, multi-point forming (MPF), thick plate, numerical simulation

The Formation and Occurrence of Non-Metallic Inclusions of Si-Doped Steel during Continuous Casting

2011 ◽  
Vol 479 ◽  
pp. 13-21 ◽  
Author(s):  
Dong Yih Lin ◽  
Sheng Min Yang
Keyword(s):  
Continuous Casting ◽  
Manganese Sulfide ◽  
Low Carbon Steel ◽  
Decisive Role ◽  
Casting Process ◽  
Inclusion Size ◽  
Test Material ◽  
Chemical Compositions ◽  
Low Carbon ◽  
Steel Material

Inclusion in steel material plays a decisive role on the purity of steels that becomes more important in the energy critical age. This study was focused on the number and morphology of inclusions with different cooling rate in the continuous casting process. A low carbon steel with 3.36 wt% silicon content was used as test material, which was soaked at 1100°C, 1250°C and 1400°C for 2 hours. The analyzed results of microstructure and chemical compositions showed the inclusions were not dissolved into matrix but formed as compounds like oxide, sulfide, and nitride after reheating at 1100°C. However, the inclusion size and average number possessed increasable trend, compared to as-cast sample. Manganese sulfide began to be dissolved into matrix by reheating at 1250°C. Some evidences showed the dissolution of aluminum nitride under the reheating at 1400°C. The inclusion size varied from 8 μm to 3 μm, and average number decreased with increasing soaking temperature.

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