Titanium is an ideal structural material. The density of titanium is only 4.5g/m3, which is 43% lighter than steel, but its strength is twice as high as iron and almost 5 times higher than pure aluminum. It has low density and high strength performance. The combination of this high strength and low density makes titanium occupy an extremely important position in technology. At the same time, the corrosion resistance of titanium is close to or higher than that of stainless steel, so it has been widely used in petroleum, chemical industry, pesticides, dyes, papermaking, light industry, aviation, space development, ocean engineering, etc.
1. Before heat treatment, oil stains, paints, fingerprints and other foreign objects (rag wire, fine iron filings, etc.) on the surface of titanium parts should be cleaned, otherwise, it will easily cause pollution during heating and affect the performance of the parts. In particular, the hazards of fingerprints should be pointed out. The high-temperature test shows that when the sample is stressed and is in contact with pure NaCl, the sample will crack, which is the result of hot salt stress corrosion. In 1955, it was discovered abroad that there were surface cracks in Ti-6Al-4V alloy samples after creep test at 371℃. Research and analysis have determined that the appearance of these cracks is usually related to fingerprints. Since fingerprints are harmful to the workpiece, you should avoid direct contact between your fingers and the workpiece during operation, and you must wear clean white gloves when taking parts at room temperature. In addition, titanium alloys must not be processed in the same furnace as aluminum, copper, etc., let alone processed in the same tray.
2. During heat treatment, the titanium parts are heated to a higher temperature and kept at the high temperature for a certain period of time. As the heated material is soft and easily deformed, the position of the parts on the tray or bracket is very important. If the tray itself is not flat, the parts will deform. If heat treatment fixtures are used to improve the deformation of parts, the expansion of parts and fixtures after heating should be taken into account at this time.
