Effect of cold rolling process on weld organization and properties of industrial pure titanium plate

Industrial pure titanium has excellent corrosion resistance in oxidizing and neutral media, and has been widely used in various fields such as petrochemical and salt production. It has been reported in the literature, industrial pure titanium by argon arc welding weld will exist in the melt pool area, heat affected zone, these two regions of the organization and the parent material organization is very different, while the melt pool area and the heat affected zone will occur in the preferential corrosion phenomenon. The plasma welding has the advantages of high energy density, line energy, efficiency and so on, with this method of welding pure titanium plate, can overcome the single-pass tungsten argon arc welding because the tungsten electrode from the molten pool closer to the tungsten electrode corrosion may occur, so that the weld seeps into the tungsten inclusions and other shortcomings.
A company sheet and strip plant coil production line using sheet welding technology to produce titanium coil, so there will be a number of deformed welds in the cold rolled coil products, these deformed welds can be used with the other parts of the coil together with the normal use of the coil has an important impact on the utilization of the coil. Researchers on the weld processing area and base material area organization, performance research, aimed at the production of welded coils for the production of the use of reference.

The experimental material is 3.5mm thick industrial pure titanium plate, grade TA1. using Nertamatic 450 automatic plasma welding machine, the two annealed state pure titanium plate welded into a whole sheet of cold rolled slab with the dimensions of 3.5mm × 1350mm × 1520mm. XXH2005 X-ray flaw detector on the weld after welding the sample plate weld non-destructive flaw detection, and metallurgical microscope to observe the base material and weld microstructure. Qualified by the flaw detection and inspection of the slab in the 1780mm cold rolling mill for two rolling process: the first rolling deformation of 43%, plate thickness reduced to 2mm, rolled 680 ℃ × 30min/AC annealing treatment; the second rolling deformation of 50%, to get the thickness of 1mm of the finished product plate, rolled 650 ℃ × 30min/AC annealing treatment.
X-ray non-destructive flaw detection inspection of the plate weld processing area of the two rolling processes; metallographic microstructure observation of the two rolling processes of the cold rolled state and the annealed state of the weld specimens; two rolling processes of the annealed state of the specimens for hardness and room temperature mechanical properties test; the use of Meters ETC1604 cupping tester for the annealed state of the finished plate for the cupping test, to examine the process performance; the use of PARSTAT-2273 electrochemical synthesis test. 2273 electrochemical integrated test system (reference electrode using saturated calomel electrode, auxiliary electrode using platinum electrode, corrosion solution is 3.5% NaCl aqueous solution), anodic polarization test on the annealed state of the finished sheet to examine the corrosion resistance. Test results:
(1) The weld quality of the pure titanium plate after plasma welding and the pure titanium plate after two times of cold deformation and annealing meets the requirements of JB/T 4730.2 standard Ⅰ.
(2) Two cold deformation plate annealed weld processing area grain size are slightly smaller than the base material area, strong plasticity is slightly better, Vickers microhardness is also slightly higher.
(3) After annealing by two rolling process cold deformation, the elongation of welded seam processing area of the plate is not much different from that of the base material, and the cupping value is similar, which has comparable process performance with that of the base material.
(4) The anodic polarization behavior of the weld processing zone is not significantly different from that of the parent material, and the corrosion resistance of the two in 3.5% NaCl aqueous solution is basically the same.