Because titanium plates, titanium rods, and titanium tubes have special physical and chemical properties, their welding process is very different from other metals. Titanium welding is a TiG welding process that effectively protects the welding area through inert argon gas. Before using argon gas, check the factory certificate on the bottle body to verify the purity index of the argon gas, and then check whether the bottle valve leaks Or failure first.
When welding titanium plates and rods, it must be ensured that:
(1) The metal in the welding zone is not polluted by active gases N, 0, H and harmful impurity elements C, Fe, Mn, etc. above 250°C.
(2) Argon gas: industrial grade pure argon, the purity shall not be less than 99.98%, and the water content shall be less than 50Mg/m3.
(3) Coarse grain structure cannot be formed.
(4) Can not produce large welding residual stress and residual deformation. Therefore, the welding process must be carried out in accordance with the predetermined construction sequence, strictly in accordance with the process quality management standards, and implement the entire process quality control. Make the factors of human, machine, material and method in a good controlled state, so as to ensure the welding quality of titanium pipe within a reasonable period of time.
Titanium welding equipment and materials:
Welding machine: DC TiG welding machine is used. The welding machine should ensure excellent working characteristics and adjustment characteristics, and be equipped with a complete ammeter and voltmeter.
Welding torch: adopt QS-75°/500 type water-cooled TiG welding torch. The welding torch should have the characteristics of simple structure, light weight and durability, tight gun body, good insulation, stable air flow, firm tungsten clamping, and suitable for welding in various positions.
Argon gas delivery pipe; semi-rigid plastic pipe is used instead of rubber hose and other hygroscopic materials. It should be dedicated when used, and should not be used in series with other gas pipes. The argon pipe should not be too long to avoid excessive pressure drop and cause instability of air flow, generally not more than 30m.
Welding fixture: Use austenitic stainless steel or copper pipe collars, locking bolts, etc. to align titanium plates and accessories. It should be ensured that there is a certain clamping force on the titanium plate and accessories to ensure that the axis is consistent and the gap is uniform and suitable.
Auxiliary equipment and tools: argon protective cover, polisher, special file, stainless steel wire brush, etc.
Titanium welding wire: The welding wire grade is ERTi-2, and the selection of welding wire should meet the following requirements:
(1) The chemical composition and mechanical properties of the welding wire should be equivalent to the base metal;
(2) If the weldment requires higher plasticity, welding wire with higher purity than the base metal should be used. The welding wire should be re-inspected before use, and the factory certificate and quality certificate should be checked; the surface of the welding wire should be clean and free of defects such as oxidation color, cracks, peeling, scars and slag inclusion.