Analysis Of Behaviour Of Dissimilar Steel Welded Joint In The Structure Of Reforming Process Pipeline Of A Reactor Block

2019 ◽  
Vol 2019 (4) ◽  
pp. 50-57
Author(s):  
S.Z. Stasyuk ◽  
2011 ◽  
Vol 391-392 ◽  
pp. 768-772 ◽  
Author(s):  
Li Yang ◽  
Zhan Zhe Zhang

The weldablity of dissimilar steel between 16MnR and S31803 was analyzed and researched. By means of optical microscope (OM), the microstructure of the weld joint was investigated, which is welded by tungsten inert gas arc backing welding (GTAW) and manual arc filling welding (SMAW). The mechanical properties and corrosion resistance of the welded joint was also tested and studied. Results indicate that austenite and acicular ferrite distribute uniformly in the weld metal, which strengths the toughness and ductility of the joint. The austenite content in weld is higher than that in over-heated zone of S31803.The SMAW joint structure is coarsening than that of GTAW and has more austenite content. It is also observed that there are a decarburization layer and a carbon-enriched zone nearby the fusion line. And very small amounts of the third phase of harmful metal phase are found in the fusion zone of S31803 side. The welded joint shows the excellent mechanical properties and corrosion resistance. The impact toughness of the weld metal is higher than in HAZ of 16MnR side, and the impact toughness at GTAW side and in HAZ is superior to the SMAW side.


2007 ◽  
Vol 561-565 ◽  
pp. 2245-2248
Author(s):  
Chun Xu Pan ◽  
Qiang Fu

The present work studied the corrosion property around the fusion boundaries of a dissimilar steel welded joint in as-welded condition and after post-weld heat treatment (PWHT) in H2S containing solution with different times. An “in-situ-tracking” observation was proceeded for evaluating corrosive progress at the fusion boundary by using a scanning electron microscope (SEM). The results revealed that the fusion boundary was the worst region for corrosion resistance when comparing with other zones, and a broad boundary had a stronger resistance for “hydrogen induced disbonding” than a narrow one.


Metals ◽  
2019 ◽  
Vol 9 (5) ◽  
pp. 509 ◽  
Author(s):  
Yuwen Qian ◽  
Jianping Zhao

The dissimilar steel welded joint is divided into three pieces, parent material–weldmetal–parent material, by the integrity identification of BS7910-2013. In reality, the undermatchedwelded joint geometry is dierent: parent material–heat aected zone (HAZ)–fusion line–weld metal.A combination of the CF62 (parent material) and E316L (welding rod) was the example undermatchedwelded joint, whose geometry was divided into four pieces to investigate the fracture toughness of thejoint by experiments and the extended finite element method (XFEM) calculation. The experimentalresults were used to change the fracture toughness of the undermatched welded joint, and the XFEMresults were used to amend the fracture toughness calculation method with a new definition of thecrack length. The research results show that the amendment of the undermatched welded jointgeometry expresses more accuracy of the fracture toughness of the joint. The XFEM models wereverified as valid by the experiment. The amendment of the fracture toughness calculation methodexpresses a better fit by the new definition of the crack length, in accordance with the crack routesimulated by the XFEM. The results after the amendment coincide with the reality in engineering.


2008 ◽  
Vol 575-578 ◽  
pp. 747-752 ◽  
Author(s):  
Guo Dong Zhang ◽  
Chang Yu Zhou

By the finite element analysis software ABAQUS and the function of coupling process between heat and stress, the welding residual stress of Cr5Mo and 20 steel joint was analyzed. In addition the heat treatment of dissimilar steel welded joint was simulated. The residual stress distributions of dissimilar steel welding and heat treatment after welding were obtained. The comparison of welding residual stress between the homogenous steel and dissimilar steel was carried out. The results indicate that the welding residual stress of the same steel is lower than that of dissimilar steel welded joint obviously. Because of the difference of thermal expansion coefficient for base metal and welding microstructure, the relatively higher residual stress is produced due to the bigger thermal expansion coefficient of base metal. The highest annular residual stress is in welding line root of internal wall, while the highest axial residual stress is in welding line surface of outer wall. The welding residual stress of dissimilar welded joint is reduced obviously after heat treatment. The research results provide the possibility for optimizing the welding procedure and improving the reliability of dissimilar steel welding joint.


The article is devoted to the actual problem of assigning optimal parameters for connecting steel plates on cover plates with angular welds that are widely used in construction practice. The article presents the results of a comprehensive study of operation of a welded assembly of the plates connection on cover plates. An algorithm is proposed for determining the optimal parameters of a welded joint with fillet welds on the cover plates, which makes it possible to obtain a strength balanced connection. The results of full-scale tensile tests of models were presented. These results confirmed the correctness of the assumed design assumptions, and made it possible to obtain a form of destruction, not characteristic and not described in the normative literature, expressed by cutting the main elements along the length of the overlap in the joint. The possibility of such a form of destruction was confirmed by the results of numerical research in a nonlinear formulation. The optimal parameters of the nodal welded joint determined by engineering calculation are confirmed by experimental studies, as well as by the results of numerical experiments on models of calculation schemes, taking into account the physical nonlinearity of the material operation. The obtained dependence for determining the bearing capacity of the joint by the cut-off mechanism and the expression for limiting the overlap length of the cover plates will make it possible to predict the nature of the fracture and design equally strong joints.


2019 ◽  
Vol 13 (4) ◽  
pp. 5804-5817
Author(s):  
Ibrahim Sabry

It is expected that the demand for Metal Matrix Composite (MMCs) will increase in these applications in the aerospace and automotive industries sectors, strengthened AMC has different advantages over monolithic aluminium alloy as it has characteristics between matrix metal and reinforcement particles.  However, adequate joining technique, which is important for structural materials, has not been established for (MMCs) yet. Conventional fusion welding is difficult because of the irregular redistribution or reinforcement particles.  Also, the reaction between reinforcement particles and aluminium matrix as weld defects such as porosity in the fusion zone make fusion welding more difficult. The aim of this work was to show friction stir welding (FSW) feasibility for entering Al 6061/5 to Al 6061/18 wt. % SiCp composites has been produced by using stir casting technique. SiCp is added as reinforcement in to Aluminium alloy (Al 6061) for preparing metal matrix composite. This method is less expensive and very effective. Different rotational speeds,1000 and 1800 rpm and traverse speed 10 mm \ min was examined. Specimen composite plates having thick 10 mm were FS welded successfully. A high-speed steel (HSS) cylindrical instrument with conical pin form was used for FSW. The outcome revealed that the ultimate tensile strength of the welded joint (Al 6061/18 wt. %) was 195 MPa at rotation speed 1800 rpm, the outcome revealed that the ultimate tensile strength of the welded joint (Al 6061/18 wt.%) was 165 MPa at rotation speed 1000 rpm, that was very near to the composite matrix as-cast strength. The research of microstructure showed the reason for increased joint strength and microhardness. The microstructural study showed the reason (4 %) for higher joint strength and microhardness.  due to Significant   of SiCp close to the boundary of the dynamically recrystallized and thermo mechanically affected zone (TMAZ) was observed through rotation speed 1800 rpm. The friction stir welded ultimate tensile strength Decreases as the volume fraction increases of SiCp (18 wt.%).


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