Since steel and titanium are not mutually fusible, it is necessary to separate steel welding and titanium welding when welding titanium-steel clad plates. It is particularly important that no titanium material exists in and around the molten pool when steel materials are welded. In the same way, when titanium material is welded, there can be no steel material in and around the molten pool. If titanium is mixed into the steel weld, welding defects such as slag inclusion in the weld will occur, resulting in the unqualified radiographic inspection of the weld. Rework. When steel is mixed into the titanium weld, the corrosion resistance of the titanium weld will drop sharply. After the equipment is in service, serious corrosion will occur in a short time. The corrosive medium will directly corrode the steel layer through the titanium layer, causing a major safety hazard.
The function of titanium cladding is to isolate the medium from the steel layer and prevent direct contact between the medium and the steel layer. It is necessary to set a cover plate on the back of the steel weld to weld the cover plate and the composite plate cladding because the cladding will directly bear the medium. Pressure, the part of the cladding that needs to be removed due to the welding of the steel layer cannot be vacant, otherwise, the cover plate will be in a suspended state, and the pressure formed by the medium will fracture the cover plate or the welding seam between the cover plate and the cladding layer, so it is necessary to install the cover plate in the cover plate. Set the pads below.
Steel base welding is submerged arc welding, which has the advantages of high efficiency and few welding defects, so submerged arc welding can be preferred, but submerged arc welding has large power and large heat input. If submerged arc welding is directly used in the first welding, The bottom edge of the V-shaped groove is thin, and a large heat input will cause the bottom edge to be melted in a large range. At this time, there is no base metal support of a certain thickness under the molten pool, which will cause the molten pool to leak due to gravity. It will cause welding failure and damage to the base metal. Therefore, the scheme of argon arc welding primer + manual arc welding filling + submerged arc welding cover can be used.
The main function of the cladding of titanium clad welding clad plate equipment is to resist medium corrosion. Titanium is a kind of active material. In the unprotected state, it starts to absorb oxygen above 300 ℃ and absorb nitrogen above 700 ℃, especially in the high-temperature molten state, and The chemical reaction of oxygen, nitrogen and hydrogen is fast, which reduces the corrosion resistance, toughness, and plasticity of the material, and requires higher cleanliness of the base metal, filler material, welding torch or welding environment during welding, and impurities will also make the material The corrosion resistance, toughness and plasticity of the titanium weld are reduced. Once the titanium weld is oxidized, its corrosion resistance will drop rapidly, and the medium will corrode the weld and the heat-affected zone in a short time. The cleanliness of the material, torch, and welding environment are very high.
First of all, do a good job of cleaning before welding, wipe the base metal within 15-20mm on both sides of the weld with a special cleaning cloth dipped in absolute ethanol, and seal it with a 20mm wide special paper tape for welding after wiping to prevent foreign matter and dust entering, and anhydrous ethanol should also be used to wipe the welding wire. Welding protection is also an important part of the welding of titanium materials. The gun gas and protective cover can protect the front of the weld, but it is impossible to protect the back of the weld with inert gas. Back protection can be achieved by introducing argon gas from the leak detector. , the welding process should be adjusted in time according to the protective effect of the weld, and a protective cover should be added if necessary. The welding method adopts GTAW, and the welding voltage, current, wire diameter, gun gas flow, and welding speed should be strictly in accordance with the parameters of the welding process. After welding, the original color of the weld should be inspected. Silver white, golden yellow, blue, and gray represent the level of weld protection quality in turn. Blue and gray are not allowed.
The above are the main points of titanium steel clad plate welding. As a professional metal-clad plate manufacturer, Baoji Taicheng Clad Metal Materials Co., Ltd can provide you with all kinds of customized metal-clad plates and answer all related questions for you. If you have any product-related questions or needs, welcome to communicate!
