Characterization of Local Mechanical Properties of X80 Pipeline Girth Welds Using Advanced Techniques

2016 ◽  
Author(s):  
Abdelbaset R. H. Midawi ◽  
Y. Kisaka ◽  
E. B. F. Santos ◽  
A. P. Gerlich
Keyword(s):  
Mechanical Properties ◽  
Yield Strength ◽  
Weld Zone ◽  
Pure Titanium ◽  
Strength Distribution ◽  
Image Correlation ◽  
Instrumented Indentation ◽  
Titanium Wire ◽  
Girth Welds

An instrumented indentation technique is proposed as a method to directly measure the local yield strength distribution in each zone of gas metal arc welds produced in X80 linepipe. The joints were produced with different microstructures and mechanical properties by applying shielding gases with varying Ar/CO2 ratios of 50 to 15% CO2 and the addition of a pure titanium wire into the weld pool was used to achieve in-situ alloying. The local yield strength distribution for each weld zone was then measured with instrumented indentation. The mapped yield strength distributions measured by instrumented indentation was compared to the hardness distribution. In addition, the yield strength of each zone obtained by instrumented indentation were then compared to tensile test results from Digital Image Correlation (DIC), in order to obtain stress-strain curves for each microstructural zone of the weld. The yield strength results obtained from both techniques are in good agreement, suggesting that instrumented indentation can be useful method to measure the local yield strengths of specific regions in a welded joint.

scholarly journals Indentation for investigation of strain rate effect on mechanical properties in structural steel weld zone

2019 ◽  
Vol 13 (3) ◽  
pp. 104-112
Author(s):  
Pham Thai Hoan ◽  
Nguyen Ngoc Vinh ◽  
Nguyen Thi Thanh Tung
Keyword(s):  
Mechanical Properties ◽  
Yield Strength ◽  
Strain Rate ◽  
Structural Steel ◽  
Weld Zone ◽  
Strain Rate Effect ◽  
Rate Effect ◽  
Steel Weld ◽  
Instrumented Indentation ◽  
Indentation Tests

In this study, instrumented indentation testing was conducted at room temperature for the investigation of the effect of strain rate on the hardness and yield strength in the weld zone of a commonly used structural steel, SM520. A number of indentation tests were undertaken at a number of strain rate values from 0.02 s-1 to 0.2 s-1 in the weld metal (WM), heat-affected zone (HAZ), and base metal (BM) regions of the weld zone. The mechanical properties including yield strength (σy) and hardness (H) in WM, HAZ, and BM were then computed from the applied load-penetration depth curves using a proposed method. As the result, the effects of strain rate indentation on yield strength and hardness in all regions of the weld zone were evaluated. The results displayed that hardness and yield strength in the weld zone’s components are influenced on the strain rate, where both hardness and yield strength decrease with the decreasing strain rate. Keywords: indentation; mechanical properties; strain rate effect; structural steel; weld zone.

scholarly journals Anti-Galling Cold, Dry Forging of Pure Titanium by Plasma-Carburized AISI420J2 Dies

2021 ◽  
Vol 11 (2) ◽  
pp. 595
Author(s):  
Tatsuhiko Aizawa ◽  
Tomoaki Yoshino ◽  
Yohei Suzuki ◽  
Tomomi Shiratori
Keyword(s):  
Pure Titanium ◽  
Solid Lubrication ◽  
Cold Forging ◽  
Contact Interface ◽  
Metallic Titanium ◽  
Low Friction ◽  
Debris Particles ◽  
Titanium Wire ◽  
Oxide Debris

A bare AISI420J2 punch often suffers from severe adhesion of metallic titanium as well as titanium oxide debris particles in dry, cold forging of biomedical titanium alloys. This punch was plasma-carburized at 673 K for 14.4 ks to harden it up to 1200 HV on average and to achieve carbon supersaturation in the carburized layer. This plasma-carburized punch was employed in the cold, dry forging of a pure titanium wire into a flat plate while reducing the thickness by 70%. The contact interface width approached the forged workpiece width with increasing the reduction ratio. This smaller bulging deformation reveals that the workpiece is upset by homogeneous plastic flow with a lower friction coefficient. This low-friction and anti-galling forging process was sustained by an in situ solid lubrication mechanism. Unbound free carbon was isolated from the carbon-supersaturated AISI420J2 matrix and deposited as a thin tribofilm to protect the contact interface from mass transfer of metallic titanium.

scholarly journals Free-Forging of Pure Titanium with High Reduction of Thickness by Plasma-Carburized SKD11 Dies

Materials ◽  
2021 ◽  
Vol 14 (10) ◽  
pp. 2536
Author(s):  
Tatsuhiko Aizawa ◽  
Tomoaki Yoshino ◽  
Yohei Suzuki ◽  
Tomomi Shiratori
Keyword(s):  
Solid Lubricant ◽  
Pure Titanium ◽  
Solid Lubrication ◽  
Single Shot ◽  
Contact Interface ◽  
Forging Process ◽  
Titanium Wire ◽  
High Reduction ◽  
Residual Strains

A tool steel type SKD11 punch was plasma carburized at 673 K for 14.4 ks at 70 Pa to make carbon supersaturation. This carburized SKD11 punch was employed for upsetting the pure titanium wire with the diameter of 1.00 mm up to the reduction of thickness by 70% in a single shot. Its contact interface to titanium work was analyzed to describe the anti-galling behavior in this forging. Little trace of titanium proved that the galling process was suppressed by the in situ solid lubrication. The isolated free carbon agglomerates are wrought as a solid lubricant to sustain the galling-free forging process. This anti-galling upsetting reduced the residual strains in the forged wires. A long titanium wire with a length of 45 mm was incrementally upset to yield the titanium ribbon with a thickness of 0.3 mm, the width of 2.3 mm, and the length of 50 mm. The grain size of original pure titanium was much reduced to 2 μm on average. A micro-pillared microtexture was imprinted onto this forged titanium ribbon.

Mechanical And Superconducting Properties Of Cu-Nb3Sn In Situ Produced Composite Wires

1981 ◽  
Vol 12 ◽  
Author(s):  
A. Kolb-Telieps ◽  
B.L. Mordike ◽  
M. Mrowiec
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Yield Strength ◽  
Wide Temperature Range ◽  
Volume Fraction ◽  
Superconducting Properties ◽  
Temperature Range ◽  
Composite Wires ◽  
Strength And Ductility

ABSTRACTCu-Nb composite wires were produced from powder, electrolytically coated with tin and annealed to convert the Nb fibres to Nb 3Sn. The content was varied between 10 wt % and 40 wt %. The superconducting properties of the wires were determined. The mechanical properties, tensile strength, yield strength and ductility were measured as a function of volume fraction and deformation over a wide temperature range. The results are compared with those for wires produced by different techniques.

scholarly journals Mechanical Properties of a Typical Jurassic Shaximiao Sandstone Under Subzero and Deep in situ Temperature Conditions

2021 ◽  
Vol 9 ◽  
Author(s):  
R. He ◽  
L. He ◽  
B. Guan ◽  
C. M. Yuan ◽  
J. Xie ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Crack Front ◽  
Image Correlation ◽  
Correlation Technique ◽  
Direct Tension ◽  
Reservoir Stimulation ◽  
The Difference ◽  
Lower Temperature ◽  
Highly Strained

Insight into the difference between the mechanical properties of rocks at low and in situ deep reservoir temperatures is vital for achieving a better understanding of fracking technologies with supercritical CO2 and liquid nitrogen. To address this issue, the fracking-related mechanical properties of the Shaximiao Formation sandstone (SS) were investigated through direct tension, uniaxial compression, and three-point bending fracture tests at a typical low temperature (Tlow) of −10°C and a reservoir temperature (Tin situ) of 70°C. The results showed that the tensile strength σt, compressive strength σc, and fracture toughness KIC of the SS were all higher at Tlow than at Tin situ, although to different extents. The KIC of the SS increased slightly more than σt at the lower temperature, while both σt and KIC of the SS increased significantly more than σc at the lower temperature. In addition to the strength, the stiffness (particularly the tensile stiffness) and the brittleness indices of SS were similarly higher at Tlow than at Tin situ. In situ monitoring using the digital image correlation technique revealed that a highly strained band (HSB) always appeared at the crack front. However, because of the inhomogeneous microstructure of the SS, the HSB did not always develop along the line connecting the notch tip to the loading point. This was a possible cause of the highly dispersed KIC values of the SS. The HSB at the crack front was notably narrower at Tlow than at Tin situ, suggesting that low temperatures suppress the plastic deformation of rocks and are therefore beneficial to reservoir stimulation.

Measurement of Weld Mechanical Properties Using an Instrumented Indentation Technique

2017 ◽  
Vol 754 ◽  
pp. 383-386
Author(s):  
Kee Nam Song
Keyword(s):  
Mechanical Properties ◽  
Heat Affected Zone ◽  
Weld Zone ◽  
Base Material ◽  
Metal Structure ◽  
Instrumented Indentation ◽  
Welded Structures ◽  
Indentation Technique ◽  
Lower Confidence ◽  
Welded Structure

Different microstructures in the weld zone of a metal structure including a fusion zone and a heat affected zone, are formed as compared to the base material. Consequently, the mechanical properties in the weld zone are different from those in the base material to a certain degree owing to different microstructures and residual welding stresses. When a welded structure is loaded, the mechanical behavior of the welded structure might be different from the case of a structure with homogeneous mechanical properties. It is known that obtaining the mechanical properties in the weld is generally difficult owing to the narrow regions of the weld and interfaces. As an alternative way to obtain the weld mechanical properties, the weld mechanical properties of Alloy800HT, SUS316L, and Alloy617, were recently measured using an instrumented indentation technique, and the representative weld mechanical properties of these materials were estimated with a 95% lower confidence level for later structural analyses of the welded structures.

Microstructure and Mechanical Properties of TiB2/ Al-Si Composites Fabricated by TIG Wire and Arc Additive Manufacturing

2019 ◽  
Vol 944 ◽  
pp. 64-72
Author(s):  
Qing Feng Yang ◽  
Cun Juan Xia ◽  
Ya Qi Deng
Keyword(s):  
Mechanical Properties ◽  
Heat Treatment ◽  
Tensile Strength ◽  
Additive Manufacturing ◽  
Yield Strength ◽  
Filler Wire ◽  
T6 Heat Treatment ◽  
Microstructure And Mechanical Properties ◽  
Before And After

Bulky sample was made by using TIG wire and arc additive manufacturing (WAAM) technology, in which Ф1.6 mm filler wire of in-situ TiB2/Al-Si composites was selected as deposition metal, following by T6 heat treatment. The microstructure and mechanical properties of the bulky sample before and after heat treatment were analyzed. Experimental results showed that the texture of the original samples parallel to the weld direction and perpendicular to the weld direction was similar consisting of columnar dendrites and equiaxed crystals. After T6 heat treatment, the hardness of the sample was increased to 115.85 HV from 62.83 HV, the yield strength of the sample was 273.33 MPa, the average tensile strength was 347.33 MPa, and the average elongation after fracture was 7.96%. Although pore defects existed in the fracture, yet the fracture of the sample was ductile fracture.

Local Elasto-Plastic Identification of the Behaviour of Friction Stir Welds with the Virtual Fields Method

2011 ◽  
Vol 70 ◽  
pp. 135-140 ◽  
Author(s):  
G. Le Louëdec ◽  
M.A. Sutton ◽  
Fabrice Pierron
Keyword(s):  
Mechanical Properties ◽  
Digital Image Correlation ◽  
Digital Image ◽  
High Speed ◽  
Weld Zone ◽  
Spatial Variations ◽  
Image Correlation ◽  
Virtual Fields Method ◽  
Full Field ◽  
Friction Stir

Welding is one of the most popular joining technologies in industry. Depending on the materials to be joined, the geometry of the parts and the number of parts to be joined, there is a wide variety of methods that can be used. These joining techniques share a common feature: the material in the weld zone experiences different thermo-mechanical history, resulting in significant variations in material microstructure and spatial heterogeneity in mechanical properties. To optimize the joining process, or to refine the design of welded structures, it is necessary to identify the local mechanical properties within the different regions of the weld. The development of full-field kinematic measurements (digital image correlation, speckle interferometry, etc.) helps to shed a new light on this problem. The large amount of experimental information attained with these methods makes it possible to visualize the spatial distribution of strain on the specimen surface. Full-field kinematic measurements provide more information regarding the spatial variations in material behaviour. As a consequence, it is now possible to quantify the spatial variations in mechanical properties within the weld region through a properly constructed inverse analysis procedure. High speed tensile tests have been performed on FSW aluminium welds. The test was performed on an MTS machine at a cross-head speed of up to 76 mm/s. Displacement fields were measured across the specimen by coupling digital image correlation with a high-speed camera (Phantom V7.1) taking 1000 frames per second. Then, through the use of the virtual fields method it is possible to retrieve the mechanical parameters of the different areas of the weld from the strain field and the loading. The elastic parameters (Young’s modulus and Poisson’s ratio) are supposed to be constant through the weld. Their identification was carried out using the virtual fields method in elasticity using the data of the early stage of the experiment. Assuming that the mechanical properties (elastic and plastic) of the weld are constant through the thickness, the plastic parameters were identified on small sections through the specimen, using a simple linear hardening model. This method leads to a discrete identification of the evolution of the mechanical properties through the weld. It allows the understanding of the slight variations of yield stress and hardening due to the complexity of the welding process.

Influence of Inhomogeneous Deformation on Tensile Behavior of Sheets Processed Through Constrained Groove Pressing

2019 ◽  
Vol 141 (4) ◽  
Author(s):  
Sunil Kumar ◽  
S. Venkatachalam ◽  
Hariharan Krishnaswamy ◽  
Ravi Kumar Digavalli ◽  
H. S. N. Murthy
Keyword(s):  
Mechanical Properties ◽  
Yield Strength ◽  
Strain Distribution ◽  
Fe Simulation ◽  
Total Elongation ◽  
Image Correlation ◽  
Lower Yield ◽  
Standard Specimens ◽  
Lower Yield Strength ◽  
Miniature Specimens

Constrained groove pressing (CGP) is a severe plastic deformation technique to produce the ultra-fine grained sheet. The inhomogeneous strain distribution and geometry variation induce differential mechanical properties in the processed sheet. The improved mechanical properties of CGP sheets is due to the composite effect of weak and strong regions formed by geometric and strain inhomogeneities. Weaker regions exhibit large strain, lower yield strength, and higher strain hardening compared to stronger regions. The estimation of mechanical properties is influenced by these defects leading to the difference in the mechanical properties along different orientations. Experimental investigation revealed that the commonly used tensile samples cut perpendicular to the groove orientation exhibit variation in thickness along the gauge length affecting the results from tensile tests. To further understand the effect of geometric variation, a typical CGP specimen was reverse engineered and finite element (FE) simulation was performed using the actual geometry of the CGP processed specimen. The strain distribution from FE simulation was validated experimentally using the digital image correlation data. Based on the numerical and experimental studies, miniature specimens were designed to eliminate the geometric effects from the standard parallel specimen. Miniature parallel specimens showed lower yield strength and total elongation compared to the standard specimens. However, the statistical scatter of total elongation of the miniature specimens was much less than that of the standard specimens, indicating better repeatability. Probably this is the first study to quantify the contribution of composite geometric effect in the mechanical properties of CGP.

scholarly journals Effect of Weld Properties on the Crush Strength of the PWR Spacer Grid

2012 ◽  
Vol 2012 ◽  
pp. 1-12 ◽  
Author(s):  
Kee-nam Song ◽  
Sang-hoon Lee
Keyword(s):  
Mechanical Properties ◽  
Material Properties ◽  
Structural Component ◽  
Weld Zone ◽  
Base Material ◽  
Instrumented Indentation ◽  
Spacer Grid ◽  
Indentation Technique ◽  
Weld Properties ◽  
Crush Strength

Mechanical properties in a weld zone are different from those in the base material because of different microstructures. A spacer grid in PWR fuel is a structural component with an interconnected and welded array of slotted grid straps. Previous research on the strength analyses of the spacer grid was performed using base material properties owing to a lack of mechanical properties in the weld zone. In this study, based on the mechanical properties in the weld zone of the spacer grid recently obtained by an instrumented indentation technique, the strength analyses considering the mechanical properties in the weld zone were performed, and the analysis results were compared with the previous research.

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