Statistical Distribution Analysis of Mechanical Properties of a Welded Pipeline Steel API X70 and Correlation between Hardness and other Mechanical Characteristics

2017 ◽  
Vol 30 ◽  
pp. 49-64 ◽  
Author(s):  
Adel Saoudi ◽  
Farida Khamouli ◽  
L'hadi Atoui ◽  
Mosbah Zidani ◽  
Hichem Farh
Keyword(s):  
Experimental Data ◽  
Mechanical Properties ◽  
Base Metal ◽  
Vickers Hardness ◽  
Pipeline Steel ◽  
Distribution Patterns ◽  
Extreme Value ◽  
Distribution Analysis ◽  
Extreme Value Distributions ◽  
Submerged Arc

The aim of this study is to model the distribution patterns of the different mechanical properties of a submerged arc welded pipeline steel API X70 and to investigate the relationship between Vickers hardness and other mechanical properties of API X70. In this study, serial mechanical properties of 70 pipes, formed by spiral submerged arc welding of high strength low alloy steel (HSLA) API X70, were measured in base metal and weldments. Four main statistical distributions: Normal, Log-normal, Weibull and smallest extreme value distributions were chosen to test the goodness of fit to the experimental data. As a result, normal and lognormal distributions can equally model the distribution patterns of the whole experimental data of studied mechanical properties except for the hardness and toughness of the base metal that can be approximated by Weibull and smallest extreme value distributions, respectively. Using the current data, a weak but statistically significant correlation is obtained only between the toughness of the fusion zone and the hardness of both the base metal and the heat affected zone. Consequently, the calculated regression models were unable to estimate impact toughness values based on future measures of Vickers hardness components.

On the Relationship of Microstructure, Toughness, and Hardness Properties in a Submerged Arc Welded API-5L Grade X65 Pipeline Steel Section

2014 ◽  
Author(s):  
Lee Aucott ◽  
Shuwen Wen ◽  
Hongbiao Dong
Keyword(s):  
Mechanical Properties ◽  
Fusion Zone ◽  
Base Metal ◽  
Weld Joint ◽  
Small Volume ◽  
Pipeline Steel ◽  
Chemical Properties ◽  
Detailed Knowledge ◽  
Upper Bainite ◽  
Submerged Arc

In order to further improve welded pipeline performance, a detailed knowledge of the key and interlinking relationships between the chemistry, microstructure and mechanical properties of the weld joint is needed. In this paper, the results of optical emission spectroscopy analysis on the as welded chemical properties of a submerged arc welded API-5L grade X65 linepipe are first presented. The microstructure of the various weld regions is then assessed against the results of the chemical analysis using a series of microscopy techniques. A fine grained ferrite-degenerate pearlite microstructure was observed within the base metal of the linepipe along with large (1.5 μm) cuboidal Ti (C, N) precipitates. Within the heat affected zone (HAZ) close to the molten weld joint, grain growth occurred with small volume fractions of induced upper bainite present within the microstructure. The fusion zone of the submerged arc weld joint consists of predominantly acicular ferrite with a small volume of grain boundary phases and a high number of large (0.8 μm) spherical Ti (C, N) precipitates. The results of Vickers hardness tests carried out at two length scales (macro + micro) show clear relations between the hardening effects of the cementite enriched degenerate pearlite and induced upper bainite phases within the base metal and HAZ respectively. Fractography analysis of Charpy impact test samples across the submerged arc welded joint found that the large Ti (C, N) precipitates within the fusion zone appear to be acting as microvoid initiation sites for the ductile fracture and as such contributing to the relatively low toughness properties within the fusion zone. Finally, the potential benefits of reducing the Ti content in both the welding wires and X65 base metal for further improvement of the mechanical properties of the linepipe weld joint are discussed in regards to reducing the size of the coarse Ti (C, N) precipitates within the base metal, HAZ and fusion zone.

Metallurgical and Mechanical Features of API 5L X65 Pipeline Steel Weldment

2002 ◽  
Author(s):  
Jang-Bog Ju ◽  
Jung-Suk Lee ◽  
Jae-Il Jang ◽  
Woo-Sik Kim ◽  
Dongil Kwon
Keyword(s):  
Mechanical Properties ◽  
Base Metal ◽  
Welded Joints ◽  
Pipeline Steel ◽  
Steel Structures ◽  
Welding Residual Stress ◽  
Engineering Structures ◽  
Steel Weldment ◽  
Mechanical Factors ◽  
Fracture Performance

Substantial differences amongst metallurgical and mechanical properties of base metal (BM), weld metal (WM) and heat-affected zone (HAZ) occur in general in welded steel structures It is common practice in various engineering structures to evaluate the fracture performance of welded structures by mechanical testing. Especially, the HAZ of steel welded joints shows a gradient of microstructure and mechanical properties from the fusion line to the unaffected base metal. This study is concerned with the effects of metallurgical and mechanical factors on the fracture performance of API 5L X65 pipeline steel weldments, as they are generally used for main natural gas transmission pipelines in Korea. First of all, we investigated the microscopic and macroscopic fracture behavior of the various micro-zones within the HAZ from the viewpoint of metallurgical factors. The effects of mechanical factors such as welding residual stress in steel weldment and strength mismatch between BM and WM, particularly in high strength steel weldments, are also analyzed. Therefore, the fracture performance of API 5L X65 pipeline steel weldment was mainly dependent on the change of macrostructure and its distribution in the welded joints.

Experimental Study on Mechanical Properties and Microstructure of 2.25Cr1Mo0.25V Steel by the Influence of Heat Treatment and Welding

2018 ◽  
Author(s):  
Qing Li ◽  
Guangxu Cheng ◽  
Mu Qin ◽  
Zaoxiao Zhang
Keyword(s):  
Mechanical Properties ◽  
Heat Treatment ◽  
Base Metal ◽  
Arc Welding ◽  
Treatment Time ◽  
Welding Process ◽  
Heat Treatment Time ◽  
Evolution Of Microstructure ◽  
Welding Metal ◽  
Submerged Arc

In this paper, the mechanical properties and microstructural changes of 2.25Cr1Mo0.25V steel under different heat treatment and welding process were investigated. The heat treatment of steel during practical processing is taken as a reference. Different heat treatment time are used to obtain samples with different condition. Automatic submerged arc welding was used to obtain welding sample. The mechanical properties of different samples are obtained by tensile test; the evolution of microstructure and precipitates of different sample with heat treatment and welding was studied on scanning electron microscopy. The experimental results show that with the increase of heat treatment time, the strength of the samples decreases and the plasticity remains nearly constant. Heat treatment also affects the precipitation of carbides; the longer the heat treatment time is, the more precipitates are. Compared with the base metal, the welding metal sample has higher strength. The amount of precipitates in welding metal is much larger than it in base metal. The research on precipitation shows that there are different kinds of precipitates which have different morphologies in welding metal.

Mechanical Properties Evaluation Method on Welded Joints of X70 Pipeline Steel Based on Vickers Hardness and Indentation Test

2018 ◽  
Vol 932 ◽  
pp. 44-48
Author(s):  
Yu Yang Wang ◽  
Jing Wang ◽  
Xiao Yang Li ◽  
Xiao Liang Gao
Keyword(s):  
Mechanical Properties ◽  
Vickers Hardness ◽  
Evaluation Method ◽  
Pipeline Steel ◽  
Indentation Test ◽  
Outer Wall ◽  
Pipe Wall Thickness ◽  
X70 Pipeline Steel ◽  
Mathematical Application ◽  
Quantitative Expression

In order to solve the problem that the mechanical properties of containers and pipelines are difficult to evaluate during service, this paper focuses on the quantitative expression of hardness and mechanical properties. Taking the X70 pipeline steel as the research object, with 12 welds of the tensile test and 192 times the hardness of indentation test, the establishment of a mathematical application suitable for engineering applications. The results shows: The hardness, indentation parameters and mechanical properties of the weld, base metal and heat affected zone did not change significantly with the pipe wall thickness, it is reasonable to test the hardness of the outer wall of the pipeline at the scene; Vickers hardness distribution can effectively explain the fracture of the specimen, hardness and plastic work was inversely proportional.

scholarly journals Characterization of Mechanical Properties and Corrosion Resistance of SAF 2205 Duplex tainless Steel Groove Joints Welded using Friction Stir Welding Process.

2020 ◽  
Vol 8 (6) ◽  
pp. 3428-3435
Keyword(s):  
Mechanical Properties ◽  
Corrosion Resistance ◽  
Base Metal ◽  
Vickers Hardness ◽  
Arc Welding ◽  
Bending Test ◽  
Friction Stir ◽  
Mechanical Properties And Corrosion ◽  
Saf 2205 ◽  
The Impact

The aim of this work is to characterize the effect of groove joint designs on mechanical and corrosion resistance properties of friction stir welded SAF 2205 duplex stainless steel (DSS) 6.5-mm-thick plate. Nondestructive tests (NDT), such as Radiographic Test (RT), and Visual Test (VT), show that, high-quality welds were produced for V grooved joints with, 60 ̊groove angle, and 2 mm root face, without root gap, with these joints were welded at constant rotating speed of 300 rpm, 25 mm/min traverse welding velocity, and 20 KN down load, using tungsten carbide (WC) base metal conical tool. Evaluating the mechanical properties using destructive tests (DT) such as tensile test, bending test, impact test, Vickers hardness test, showing that, Vickers hardness was increased at the stir zone, the failure was occurred at the base metal, the bending behavior and the impact energy are acceptable, the evaluation of corrosion resistance rate shows that, the corrosion resistance of this joint is higher than that of the base metal. In addition, it was significantly noted that, mechanical properties and corrosion resistance of these joints welded using FSW process are better than that of those joints welded using fusion welding (FW) possesses, shielded metal arc welding (SMAW), and gas tungsten arc welding (GTAW).

scholarly journals Analysis of the Microstructure and Mechanical Properties of TiBw/Ti-6Al-4V Ti Matrix Composite Joint Fabricated Using TiCuNiZr Amorphous Brazing Filler Metal

Materials ◽  
2021 ◽  
Vol 14 (4) ◽  
pp. 875
Author(s):  
Hao Tian ◽  
Jianchao He ◽  
Jinbao Hou ◽  
Yanlong Lv
Keyword(s):  
Mechanical Properties ◽  
Base Metal ◽  
Matrix Composite ◽  
Room Temperature ◽  
Filler Metal ◽  
Ceramic Fiber ◽  
Tensile Fracture ◽  
Alloy Matrix ◽  
Composite Joint ◽  
Secondary Cracks

TiB crystal whiskers (TiBw) can be synthesized in situ in Ti alloy matrix through powder metallurgy for the preparation of a new type of ceramic fiber-reinforced Ti matrix composite (TMC) TiBw/Ti-6Al-4V. In the TiBw/Ti-6Al-4V TMC, the reinforced phase/matrix interface is clean and has superior comprehensive mechanical properties, but its machinability is degraded. Hence, the bonding of reliable materials is important. To further optimize the TiBw/Ti-6Al-4V brazing technology and determine the relationship between the microstructure and tensile property of the brazed joint, results demonstrate that the elements of brazing filler metal are under sufficient and uniform diffusion, the microstructure is the typical Widmanstätten structure, and fine granular compounds in β phase are observed. The average tensile strength of the brazing specimen is 998 MPa under room temperature, which is 97.3% of that of the base metal. During the high-temperature (400 °C) tensile process, a fracture occurred at the base metal of the highest tensile test specimen with strength reaching 689 MPa, and the tensile fracture involved a combination of intergranular and transgranular modes at both room temperature and 400 °C. The fracture surface has dimples, secondary cracks are generated by the fracture of TiB whiskers, and large holes form when whole TiB whiskers are removed. The proposed algorithm provides evidence for promoting the application of TiBw/Ti-6Al-4V TMCs in practical production.

scholarly journals An Additive Model to Predict the Rheological and Mechanical Properties of Polypropylene Blends Made by Virgin and Reprocessed Components

Recycling ◽  
2021 ◽  
Vol 6 (1) ◽  
pp. 2
Author(s):  
Francesco Paolo La Mantia ◽  
Maria Chiara Mistretta ◽  
Vincenzo Titone
Keyword(s):  
Experimental Data ◽  
Mechanical Properties ◽  
Additive Model ◽  
Industrial Process ◽  
Theoretical Predictions ◽  
Experimental Values ◽  
Polypropylene Blends ◽  
Polypropylene Sample

In this work, an additive model for the prediction of the rheological and mechanical properties of monopolymer blends made by virgin and reprocessed components is proposed. A polypropylene sample has been reprocessed more times in an extruder and monopolymer blends have been prepared by simulating an industrial process. The scraps are exposed to regrinding and are melt reprocessed before mixing with the virgin polymer. The reprocessed polymer is, then, subjected to some thermomechanical degradation. Rheological and mechanical experimental data have been compared with the theoretical predictions. The results obtained showed that the values of this simple additive model are a very good fit for the experimental values of both rheological and mechanical properties.

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