1.Experimental conditions
The base layer of the titanium steel composite plate is a 30mm thick carbon steel plate, designated as (JIS) SB410, and the cladding layer is a 5mm thick industrial pure titanium plate, designated as (JIS) TP28H. The chemical composition and mechanical properties are shown in Table 1. The low-carbon steel plate is Q235-A with a thickness of 20mm. The welding rod is J422, p5mm. The welding equipment is a 2-400 silicon rectifier welding machine, which is used for reverse welding.
2. Joint form and welding parameters: According to the design structure of the condenser, T-joint welding test and post weld inspection shall be conducted. (1) After welding, the appearance size of the T-joint shall be inspected, and the deformation shall be 2mm.
(2) Cross section dye penetrant testing shows no peeling phenomenon on the bonding surface of the composite board.
(3) Composite strength test, shear specimen Figure 31. Titanium layer 2. Carbon steel layer: Take the specimen at the position of maximum deformation in the composite plate
Sample preparation of titanium steel composite tube plate sample material, tube plate hole+0.05 diameter size of p25+0.1omm, hole wall roughness of Ra6.3. Tube specification of p25mmx0.5mm, chemical composition and mechanical properties of the tube
3. Welding quality inspection
(1) The dye penetrant inspection of the weld seam shows no defects.
(2) The tensile test results of the welded parts showed that there was no pull-out phenomenon in all three groups of samples, and the final fracture occurred in the middle section of the titanium tube, with the maximum tensile breaking force
(3) The longitudinal section inspection of the sample shows that the longitudinal penetration depth of the weld is 1.5-2.0mm, and the residual height is 0.4-0.5mm. There is no peeling phenomenon on the joint surface of the composite board of the three groups of samples
)The welding of composite plates and steel plates is carried out using a high welding current, and there is no peeling phenomenon on the bonding surface between the composite layer and the base layer of the composite plate, and the bonding strength is not significantly reduced. However, while ensuring the performance of the joint, a slightly lower current and faster welding speed should be used as much as possible, and the heat input should be controlled as much as possible to prevent the impact of overheating. The T-shaped joint undergoes a certain amount of deformation after welding, and the protruding part happens to be the part where the sealing strip is pressed, which is beneficial for sealing. Therefore, there is no need to try to prevent welding deformation in production.
(2) The welding test between composite tube plate and titanium tube proves that when the thickness of titanium coating is not less than 2.5mm, argon arc welding has no effect on the bonding of the composite plate joint surface. Therefore, there is no need to increase the thickness of the composite layer to increase the cost. The welding process parameters can basically refer to the parameters of sealing welding between pure titanium tube plates and titanium tubes.
