The welded joint design of titanium equipment is similar to that of other metals, but titanium has small thermal conductivity, low melting point and greater fluidity of molten titanium. Therefore, the pure edge gap is smaller than other metals. Because of this, if the weld stays in the high-temperature area for a long time, it is easy to cause coarse grains in the weld area and reduce stray. Therefore, measures should be taken to accelerate the cooling of the weld area. However, if it is cooled too fast, acicular martensite is easy to form, which makes the weld brittle. Therefore, when designing titanium equipment, it should be noted that titanium is often used for welded joints. The weakest link of pressure vessel shall be large-size titanium plate as far as possible to reduce welds and avoid cross welds.
Titanium equipment industrial pure titanium is very sensitive to crevice corrosion, so crevices should be eliminated as much as possible in the design of titanium equipment. For example, use corrosion-resistant cavity mud or plastic to gamble the gap, or use welding instead of bolt connection or expansion, etc. For gaps that cannot be eliminated (such as sealing surface of flange connection), permeability, expansibility and surface wettability shall be guaranteed. Selected. The gasket is made of small materials, and the flange sealing surface is made of crevice corrosion-resistant titanium alloy.
8. At room temperature, the tensile curve section of industrial pure titanium has obvious physical yield phenomenon. The conditional yield strength is very close to the tensile strength. The ratio of yield strength such as 0 to tensile strength increases with the increase of strength. However, when the tensile strength is about 390mpa, the yield ratio is 0 and 75; When the tensile strength is about 680mpa, the yield ratio is 0 and 85. Therefore, the safety factor should be selected according to the yield ratio when designing titanium equipment.
