SS316L Stainless Steel Clad Steel Plate

The welding groove of clad plate can be machined by mechanical cutting. There are three specific methods: plasma cutting, gas cutting and oxygen flux cutting. Rust must be removed before cutting. The shearing equipment shall be selected according to the capacity. The SS316L Stainless Steel Clad Steel Plate shall be cut mechanically and measures shall be taken to prevent surface damage and delamination. The groove processing shall be carried out on the edge planer or other machine tools as far as possible. When punching, the multiple layers shall be upward to avoid layering or scratching. The groove of the welding element shall be inspected, and there shall be no cracks or layering, otherwise, repair shall be carried out. Before welding, the size of welding edges shall be checked. The gap between edges shall meet the requirements of drawings and relevant standards. The groove type of welding joints is shown in Figure 1.

Fig. 1 Groove Type of Welded Joint

 

Refer to Table 1 for the selection of welding materials according to various stainless steel materials.

The current of argon arc welding is generally 130~160 A. DC reverse short arc fast welding (arc length is 2 The current is generally 20% lower than that of carbon steel welding (less than 5 mm). I welding=(25-35) d, and transverse swing is not allowed during welding. The selected welding methods and specifications are shown in Table 2.

Table 1 Selection of Common Welding Materials

Table 2 Recommended Welding Methods and Specifications

Due to the large linear expansion coefficient of stainless steel, the interpass temperature (below 150 ℃) shall be strictly controlled during multi-layer welding to avoid serious deformation and reduction of intergranular corrosion resistance due to overheating of the weld. If necessary, cold water can be applied at the back. Argon arc welding and welding rod arc welding shall be conducted in the groove. The arc striking part shall be re fused once during welding, and the arc crater shall be filled during arc extinguishing. The arc striking and arc extinguishing of automatic submerged arc welding are carried out on the run-on plate and arc extinguishing plate. During multi-layer welding, pay attention to the cleaning of the flux for the welding rod arc welding.

And the welding rod joints of the two adjacent layers must be staggered, and the weld in contact with the medium shall be welded finally. All welds requiring non-destructive testing must be back gouged or argon arc welded. In order to ensure that the composite plate will not lose its original comprehensive performance, when the composite plate is butt jointed, the base layer shall be welded first, and the welding materials corresponding to the base layer shall be selected; Then, weld the transition layer, and select the welding materials with high chromium and nickel content; Finally, the welding materials corresponding to the cladding shall be selected for welding the surface layer. After each weld is welded, the slag and spatter shall be cleaned up, and the appearance inspection shall be carried out. The weld surface shall be free of undercut, and non-destructive testing can be carried out only after it is qualified. For the maintenance of welding equipment and welding process technology, refer to the relevant welding rod electric arc welding process specification. The welders engaged in tack welding shall be qualified welders. The welding materials used for tack welding are the same as those used for formal welding process. The distance between spot welding is smaller than that of carbon steel. The length of spot welding is generally 20~25 mm. The height of spot welding shall not exceed 2/3 of the groove depth. Cracks on the weld surface and heat-affected zone are not allowed. The welding seams of weldments are shown in Figure 2. must not undercut, over burning and air hole are found on the surface of the weld seam of the cladding layer, and the undercut depth of the weld seam of the base layer must be ≤ 0 5 mm, continuous length ≤ 100 mm, the total length of each weld undercut (i.e. the sum of both sides of the weld) shall be greater than 10% of the weld length. The clad weld shall be subject to penetrant testing in accordance with JB/T4730-2005 Nondestructive Testing of Pressure Equipment, and it is qualified if the testing result reaches Grade I.