Zr and Ti in first IV class element in the periodic table, is live dial, metal of C, N, O2, H2 has a strong affinity. Zirconium has high chemical activity. When heated to 200, it reacts with oxygen; When you heat up to 300, you start to react with the hydrogen; When you heat up to 400, you start to react with nitrogen. A small amount of dissolved hydrogen, oxygen and nitrogen can increase the hardness of zirconium and reduce the ductility of zirconium. Zirconium will also react with carbon and carbide at high temperatures to increase brittleness. 1.5 USES for the reactor structural materials, neutron radiation resistance, chemical corrosion resistant materials, corrosion resistance of zirconium is better than stainless steel, nickel and nickel alloy, titanium zirconium is second only to the resistance to sulfate corrosion of metal materials, the hydrochloric acid corrosion resistance is superior to other metals, about the titanium.
Zirconium materials are used in chemical corrosion resistant materials, which are still in the initial stage in China and lack of mature welding experience. Titanium as chemical corrosion resistant material, is widely used, according to relevant data, zirconium good weldability, crack tendency is very small, can use a variety of methods of welding, usually adopt tungsten argon arc welding (GTAW), melting pole argon arc welding (GMAW), plasma arc welding (PAW), vacuum electron beam welding to welding zirconium metal, zirconium welding usually do not need to preheat. Preheating can be used in places with low temperature or high humidity as an auxiliary means of dehumidification. Welding, greater than 300 ℃ the area (including the weld seam and heat affected zone, parent metal and weld back) must be argon gas protection. Zirconium above 590 ℃, the sensitivity to the brittleness of O2, N2 and H2, so the metal welding must be preserved, to prevent air pollution. Zirconium wire must be chemically cleaned to ensure no serious oxidation, no water, gasoline, rust and other contaminants.
Zirconium and zirconium alloy welding should be carried out indoors, the ground clean, clean air clean. The welding site should be isolated from the steel work area and avoid the production of dust. The relative humidity of the environment should be less than 80%, the ambient temperature should not be less than 5, the wind speed is less than 0.5m/s, and the fan shall not be used to send the fan to the welding zone to smoke.
