1 Products Description

Because of its excellent corrosion resistance, titanium is widely used as a material for various chemical reaction vessels and heat exchangers, but the disadvantage is that the cost is high, and the use of titanium composite plates can effectively solve this problem. Titanium clad plate is a new type of bimetallic high-efficient energy-saving material, which is made of titanium as the cladding, carbon steel or low alloy steel as the base layer, by explosive bonding or rolling and crimping. The titanium clad steel plate for pressure has the high strength and the corrosion resistance of the coated titanium metal can not only save a lot of titanium materials, but also have the properties that any single metal does not have. Therefore, compared with pure titanium, the equipment barrel, tube plate and head made of titanium clad steel plate for pressure can not only ensure the performance, but also significantly reduce the project cost.

2 Difficulties analysis of titanium composite plate

The difficulty of titanium clad plate welding is the treatment of the transition layer between titanium and steel. If fusion welding is adopted directly, brittle intermetallic compounds such as FeTi and Fe2Ti will be formed in the fusion zone. These intermetallic compounds and eutectic with low melting point will sharply improve the strength of the material, greatly reduce the plasticity of the material, and directly affect the mechanical properties of the welded joint. In addition, due to the large difference in the thermophysical properties between titanium and steel, the shrinkage of the weld is uneven during the cooling process, resulting in large welding internal stress, and even leading to weld cracking in serious cases. Therefore, it is almost impossible to form a continuous welded joint between titanium and steel directly by fusion welding.

3Influence of gas flow and nozzle size on protection effect

When welding titanium coating, manual TIG welding is required. Compared with stainless steel, titanium coating has poor thermal conductivity and large weld pool diameter. Therefore, using the same nozzle as welding stainless steel cannot achieve ideal protection effect. For this reason, nozzles with different sizes of 5 #, 7 #, 9 # and 15 # were used respectively. Under the same other conditions, test whether changing the gas protection range has an impact on the welding quality.

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4 Welding method and equipment

Because the base layer is carbon steel or low alloy steel, its welding process is relatively mature in China. The most common welding methods are electrode arc welding and CO2 gas shielded welding. The electrode arc welding is used in this test. For the titanium coating, because of its high chemical activity, welding methods such as electrode arc welding and CO2 gas shielded welding cannot be used for welding. At present, the commonly used welding methods are argon tungsten arc welding, submerged arc welding and vacuum electron beam welding. Considering the production efficiency, welding cost and site construction environment, the commonly used argon tungsten arc welding method was finally selected.

5 Base metal Base metal material

The covering layer is GR3 titanium plate, and the base layer is Q345R steel plate.

Base metal thickness: 2mm for the covering layer and 16mm for the base layer. The titanium filler plate and titanium cover plate are made of GR3 with a thickness of 2mm.

6 Welding materials

(1) The base material is carbon steel or low alloy steel. Due to the stress, segregation, alloying elements and other reasons, the tendency of cracking will increase. To ensure the welding quality, the basic carbon steel electrode with the model of E5015 is selected as the welding material. In order to adapt to the groove size and ensure welding efficiency, two kinds of welding rods with diameters of d3.2mm and d4.0m are used

(2) The titanium coating adopts pure titanium welding wire GR3ELI with a diameter of 2.0mm.

7 Groove processing and weld bead arrangement

The groove form used in welding is shown in Figure 6. Generally, cold machining method can be used for groove processing, and plasma arc cutting method can also be used. During groove processing, attention should be paid to the protection of titanium coating surface. After groove processing, both sides of the groove and the surface of titanium coating shall be inspected. If scratch or damage is found on the surface of titanium coating, it shall be repaired in time. The titanium clad plate shall be welded with the carbon steel base weld first, and the titanium clad weld shall be welded after passing the inspection. Take the titanium composite plate with the thickness of base steel plate of 16 mm and titanium clad plate of 2 mm as an example, and the weld bead arrangement is shown in Figure 6.

Titanium Clad Steel Plate for Pressure price