Titanium is widely used in Marine industry because of its good corrosion resistance. Most Marine titanium alloys have excellent welding properties. Alloy used in the process, according to the characteristics of various kinds of alloy, the structure of the working conditions of use, joint form, properly design to choose reasonable welding material and make reasonable welding process, provide a good and reliable welding high gas protection and adopt measures to eliminate stress, correctly is to ensure that get the key to good comprehensive performance of Marine titanium alloy welded joint.

Titanium is widely used in Marine industry because of its good corrosion resistance. Most Marine titanium alloys have excellent welding properties. Alloy used in the process, according to the characteristics of various kinds of alloy, the structure of the working conditions of use, joint form, properly design to choose reasonable welding material and make reasonable welding process, provide a good and reliable welding high gas protection and adopt measures to eliminate stress, correctly is to ensure that get the key to good comprehensive performance of Marine titanium alloy welded joint. Existing a seawater cooler manufactured by our company for China national offshore oil corporation, with the following equipment parameters: heat exchange area of 30m2, diameter of 400mm. Pipeline medium: seawater; Design pressure: 1. 3Mpa; Design temperature: 35℃; Main material :TA2. Shell side medium: natural gas; Design pressure: 1. 0Mpa; Design temperature 175℃; Main material :Q345R. Wherein, the tube section is made of material TA2 with a thickness of 10mm; Tube plate material :TA2, thickness: 45mm; Specification of heat exchange tube: phi 19×2, material: TA2. Heat exchange tube and tube plate are connected by strength welding.

Titanium and titanium alloys are widely used in aerospace, petrochemical, shipbuilding and other parts due to their low density, high strength, excellent heat and corrosion resistance. Titanium is a very active metal, which has a strong affinity with carbon, hydrogen, oxygen and nitrogen at high temperature, and generates brittle compounds such as titanium hydride, titanium carbide, titanium oxide and titanium nitride in the welding seam, so as to reduce the ductility and toughness of the welding seam. Due to its low thermal conductivity and high melting point, titanium is prone to heat concentration during welding. Too long residence time at high temperature will lead to large weld grains and reduce the comprehensive performance of welded joints. At present, high performance aircraft, tanks are using titanium alloy parts, and in the petrochemical part of titanium alloy parts are gradually expanding the scope of use. And titanium alloy in aircraft and its engines and petrochemical applications, inevitably need to use welding means to connect, which is of great significance to expand the application range of titanium alloy. With the rapid development of science and technology and economy, more and more extremely strict requirements have been put forward for steel materials. Light energy-saving vehicles, high-speed railways, heavy-duty Bridges, oil and gas transmission pipelines, engineering machinery, large ships and other fields all need a large amount of steel with good performance, long service life and low price. This problem has aroused the attention of the governments and experts in the field of steel and iron materials. Microalloy steel has developed rapidly in many fields because of its excellent performance and relatively low cost. With the expanded use of steel in various fields, it is necessary to adopt increasing welding molding process Settings, studies have shown that high strength steel, low alloy using micro alloying elements such as Ti, Nb, V, TiN in steel, NbN,.vn particles such as inhibition of the austenitic grain size grew up, which can effectively improve the strength of the using method of large heat input welding steel, and improve welding coarse grain heat affected OuDeRen degrees. By proper heat treatment after welding can make Ti mainly take the form of TiC/N in the weld, TiC/N face-centered cubic structure and steel face-centered cubic, a coherent body centered cubic matrix, under certain conditions can either into and precipitation, through its carbon, nitrogen, particle size (less than 5 nm) dispersion of precipitation and Ti solid solution refining grain precipitation strengthening, greatly improve the strong toughness of weld metal. Therefore, it has a great application prospect to study the existing form of titanium in weld metal and its influence on the microstructure and properties of weld metal under post-welding heat treatment.