| The metal composite plates have excellent comprehensive properties, and they are widely used inmany industry fields such as petrochemical, construction industry, transportation and daily products,etc. Due to the great difference of chemical composition and physical and chemical propertiesbetween the cladding plate and the base plate, it can easily result in the weld dilution, compositionsegregation and the occurrence of other weld defects during welding, thus it is difficult to obtain awelded joint with good quality. In the practical application, when the composite plate is welded, thecladding plate and the base plate of composite plate are often welded respectively, and a transitionlayer is adopted between the base plate and the cladding plate, so as to decrease the weld dilutionduring welding. In order to get welded joint with good quality, the technology control of welding forthe transition layer is of great concern. Based on these, the welding technology and weldability of304L/SA516Gr70、405/Q245R stainless steel composite plate are investigated respectively in thecurrent work..According to the welding characteristics of the stainless steel composite plates, the stainlesssteel/carbon steel composite plates are welded by tungsten inert gas arc welding (GTAW) andshielded metal arc welding (SMAW) respectively, and the filler metals such as welding wire ER309L,welding wire ER316L and electrode A302which contain high contents of Cr and Ni elements areadopted, and the groove pattern of welded joint are X-groove and slotted X-groove respectively. Inorder to optimize the welding technology and get the most suitable joint, the mechanical properties,microstructure and corrosion resistance of welded joints under different condition are evaluatedrespectively.Reasults of mechanical properties tests show that the tensile strength of both of the two compositeplates welded joints are similar with the tensile strength of base metal, and all the tensile samplesbroke at the position of base material distant from fusion line. Consequenly, it can meet therequirement of tensile strength for practical engineering structure. The tensile strength of slottedX-groove joint A2weled by SMAW is the highest among all of the304L/SA516Gr70joints, while inthe405/Q245R joints, the tensile strength of joint B2weled by SMAW is higher than that of joint B1weled by GTAW.Joint microstructure analyses including the transition layer weld metal, the interface betweencladding layer stainless steel and weld metal (WM-SS), the interface between base layer carbon steel and weld steel (WM-CS), and chemical compositions and phase constitution of stainless steel/carbonsteel composite plate joints are conducted by means of optical microscopy (OM), scanning electronmicroscopy (SEM) and transmission electron microscopy (TEM), together with X-ray diffraction(XRD) respectively. Results show that the microtructure of weld metal is that the ferrite distributes inthe austenite matrix. In the WM-CS interface, both of the two stainless steel composite plate jointsexist the migration of carbon element to a certain extent. In addition, the304L/SA516Gr70joint stillhas a solidification transition region which its width is30~50μm. The analyses of element linescanning and energy spectrum indicate that the variations of Cr, Ni contents obviously present thecharacteristic of gradient distribution, but there is not element segregation and precipitation ofdeteriorative phases in the interface.Chemical immersion method and electrochemical test are used respectively to evaluate the pittingcorrosion resistance of joint transition layer. Reasults show that the pitting corrosion resistance ofjoint A4weled by GTAW with welding wire ER316L is better than that of the other304L/SA516Gr70joints, and the pitting corrosion resistance of joint B2weled by SMAW is betterthan that of the joint B1weled by GTAW.In a word, under such experiment conditions, the welded joint of stainless steel/carbon steelcomposite plates can be successfully welded to a certain extent. |
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