Nickel is a rare metal, it is better weldability, but during the welding process, as the temperature increases, its performance begins to change, the absorption of nitrogen, hydrogen, oxygen, along with a marked increase in capacity, the gas impurity contamination easy to cause embrittlement of welded joints. Therefore, during the welding process the nickel tube, a series of protective measures must be taken to improve the quality of welding of nickel tube, TNTI company through self-argon shield to achieve this purpose.
This protective cover is based on the joint form, welding process parameters selected, dragging cover structure and size is determined by the geometry of the weldment, usually with 0.8mm thick copper plate do grow 40mm ~ 100mm, width 30mm ~ 60mm shell thin weldments shorter, thick weldment longer, wider. Argon from the intake manifold into the distribution pipes, distribution pipes φ6mm × 1mm stainless steel tubing, drill pipe at the top two rows of holes 0.8mm ~ 1.0mm in diameter, pitch of 8mm ~ 10mm, the filter with a 0.152mm × 0.152 (100 mesh) made of copper mesh, filter weldment distance to not less than 8mm, inflatable indoor should not have corners, in order to achieve all of argon air out, as far as possible inside the protective cover made of smooth transition, prevent too large a stream of argon to form a vortex, so the process of welding the nickel tube argon inlet pipe into the distribution pipe above the discharge by a homogeneous distribution and buffering. When the air flow through the copper mesh, the right again to get re-distribution, which improves the flow of argon gas state, so the pool of metal directly under argon stratospheric protection solidified forming. Gun and dragged integral cover during use in order to operate.
Welding fixture should be of sufficient strength and good thermal conductivity, with a water-cooled copper plate fixture can meet the above requirements. After determining the fixture and protective cover, choose a purity of 99.99% argon gas (argon purity test method, in an argon gas bottle before use, according to the norms of normal spot welding nickel plate number of points, with silver solder white surface such as a mirror is qualified), different gas flow adjustment, observe the protective effect, and finally determine the appropriate shielding gas flow. Nickel pipe before welding the nickel surface oxide film should be cleaned, as soon as possible to clean up after welding, storage time is generally not more than four hours.
TNTI company to avoid during welding of nickel oxide high temperature region a serious problem with a homemade argon shield, combined with other protective measures and reasonable welding specification, significantly improves the quality of welding of nickel tube.