Influence of casting process on titanium castings
The effect of casting channel on casting integrity
Due to the poor casting performance of titanium, the setting of the casting channel of the titanium casting mold is particularly important. If the vertical casting channel is cast by the method of casting cobalt-chromium alloy and stainless steel, casting incompleteness often occurs. The casting channel for casting titanium investment mold has the following requirements:
The diameter of the casting channel should be thick (not less than 4mm) and short, to ensure that the titanium liquid has a sufficient amount and be injected into the casting cavity through the shortest way; the connection between the casting channel and the investment mold should be properly thickened; the number of casting channels should be 3 ~ 4; parallel interpolation or lateral interpolation can be used; avoid forming right angles. Effect of the temperature of the second mold on the surface properties of titanium castings
Titanium liquid is contaminated by the embedding material, in addition to the vacuum degree of the melting casting chamber and the composition of the embedding material, but also the mold temperature. When the mold temperature is high, the titanium liquid easily reacts with the embedding material, and Zr, Al, Si and other elements easily diffuse into the titanium matrix to become interstitial elements, forming a thicker hardened layer, thereby making the tensile strength and yield of the casting Strength increases, ductility decreases, and brittleness increases. Among them, the increase of oxygen content has the most obvious change on the mechanical properties of castings. When the mold temperature is low, the hardened layer also becomes thinner. But when the mold temperature is low, it will affect the casting flow rate, so the mold temperature should be properly selected, and sometimes the mold temperature should be determined according to different purposes.