Compared with other pipes, titanium plates of mechanical equipment have higher resistance to internal force and pressure, better corrosion resistance and wear resistance. It has the advantages of convenient construction, good sealing performance of the interface, and large safety factor of operation. In recent years, the momentum of development in the market of titanium casting materials has been rapid.
This kind of material is easy to show three quality problems: crack, heavy skin and slag inclusion. Cracking occurs with the process of centrifugal pouring, and the pouring criterion occurs unreasonably; heavy skin is related to pouring temperature and pouring speed; slag inclusion is related to the content of metal chemical elements and slag disposal.
Avoidance and manipulation methods are:
1. Improve the centrifugal equipment to avoid cracks
Reducing the residence time of titanium liquid at high temperature, strengthening the inoculation, especially the inoculation effect. The amount of inoculant participating in the flow control is 0.1-0.25% of the amount of titanium liquid; ensure that the powder of the pipe mold is evenly distributed, and the dosage of the inside and outside of the pipe mold is 20-30g / m2. Control the technical parameters of water-cooled metal centrifuge exercise.
The centrifuge should avoid the turbulence of the trough to form a splash of titanium liquid, and the socket sand core should be placed properly to avoid burrs. To control the composition of the titanium liquid and reduce the silicon content of the titanium liquid, it is appropriate to control the W (Si) at 0.8-1.2% after the spheroidizing agent is punched in. The arc-shaped spray cooling pipes are evenly arranged in the centrifuge casing, and are arranged in sections to avoid the mutual influence of the cooling water of each section.
2. Optimize the technical parameters and reduce the weight of the tube body
Reasonably control the pouring temperature and the inlet and outlet temperature of the cooling water of the fuselage, shorten the interval between two castings. The inlet temperature of the cooling water of the control fuselage is 28-36 ℃, and the outlet temperature is 50-57 ℃.
In the water-cooled metal-type centrifugal casting technology, excessive casting speed should be avoided, and the appropriate ladle turning speed and host walking speed should be adjusted; ensure that the depth of the pipe mold is 0.25-0.3mm, the diameter is 4-5mm, points and points The marginal distance is 0.5-0.7mm.
3. Control the material to participate, and reduce the disadvantages of slag inclusion
In order to deal with the reduction of the sulfur content in the titanium liquid and reduce the occurrence of sulfides, the W (S) <0.02% should be controlled; the casting temperature should be appropriately increased to help the slag float up; It is better to control it at 1-2%; strengthen the slag picking and slag blocking effect of the titanium liquid; the residual magnesium flow in the titanium liquid is not easy to be too high (controlling at 0.035-0.045%) to reduce the external oxidation of the titanium liquid.
After adopting the above corresponding methods, the quality of the titanium plate of mechanical equipment has been significantly improved, and the defects of cracks, heavy skin, and slag inclusion have been greatly reduced, scraps have been reduced, and the rate of induction has been greatly improved.