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采用金相法测量了TC18钛合金相变温度,利用L78 RITA型快速加热热膨胀仪,测定了不同焊接冷却速率下TC18钛合金的膨胀量曲线,结合金相分析和硬度测试,得到了不同冷却速率下试样的显微组织和硬度,测绘了TC18钛合金的焊接条件下的CCT曲线。结果表明:TC18钛合金的相变温度为(855±5)℃;随着冷却速率增加,析出α相的数量逐渐减少,且由片层状向团簇状结构转变。当冷却速率低于0.8℃/s时,α相以片层状形貌析出,当冷却速率高于0.8℃/s时,α相以团簇状析出,且析出的片层或团簇状颗粒均随冷却速率的增加而细化;当冷却速率超过10.0℃/s后,亚稳β相的转变受到抑制,基本上被完全保留下来。
The phase transition temperature of TC18 titanium alloy was measured by metallographic method. The expansion of TC18 titanium alloy with different welding cooling rate was measured by L78 RITA rapid heating dilatometer. Combining the metallographic analysis and hardness test, Like the microstructure and hardness, mapping the TCT titanium alloy welding conditions CCT curve. The results show that the phase transition temperature of TC18 titanium alloy is (855 ± 5) ℃. With the increase of cooling rate, the amount of precipitated α phase decreases gradually and changes from lamellar to clustered structure. When the cooling rate is lower than 0.8 ℃ / s, the α phase precipitates in lamellar morphology. When the cooling rate is higher than 0.8 ℃ / s, the α phase precipitates in clusters and the precipitated lamellar or cluster particles When the cooling rate exceeds 10.0 ℃ / s, metastable β-phase transformation is inhibited, basically completely preserved.