Gr.12钛管加工工艺研究

Study on Manufacturing Process of Gr.12 Titanium Tubes

采用相同模具不同挤压工艺、相同挤压工艺匹配不同的模具硬度及表面粗糙度制取Gr.12钛管坯,对挤压后管坯内壁有缺陷部位进行了SEM、EDS分析;将不同轧制工艺制备的管材进行超声探伤、矫直对比分析。发现管坯内壁有缺陷部位存在钛/铜共晶现象;当模具硬度HRC≤35、表面粗糙度Ra≥1.6μm时,挤压后的管坯表面质量不稳定;当采用单铜包套挤压制取管坯时,挤压针的硬度下降较快,管坯内壁质量较差;挤压制坯时采用内孔铜/钢双包套,挤压温度760～790℃,挤压比不大于18时,可以稳定地得到表面质量较高的Gr.12管坯,挤压针的硬度下降较为平缓。当在管坯开坯前预先对管坯进行Q≤0.1、ε≤35%的加工,然后再进行轧制且轧制时道次间的变形量不大于52%时,可以得到表面质量较好的成品管材。按照以上工艺进行批量加工时,管材轧制及矫直时的裂纹发生率≤1‰,其无损超声检验合格率可以达到95%以上。

Gr.12 titanium extrusion tube billets were obtained adopting same mould and different extrusion processes, the defect parts of the extrusion tube billet wall were analyzed by SEM, EDS. The tubes obtained with different rolling processes were comparatively analysised by ultrasonic test and straightening. Titanium copper eutectic phenomenon is found in the defective parts of the extrusion tube billet. The surface quality of the extrusion tube billet is not stable when mold hardness HRC is less than 35 and surface roughness Ra is greater than 1.6 μm. The hardness of extrusion needle decreases rapidly and the inside surface quality is poor when the sheath is the copper material. The hardness of extrusion needle decreases slowly and the inside surface quality is better when extrusion temperature is 760- 790 ℃, extrusion ratio is less than 18 and the sheath is the steel/copper composite. The surface quality of the finished product tube is better adopting pre-rolling by Q≤0.1, ε≤35% and deformation degree per pass is less than 52%. The rolling and straightening cracking rate is less than 1‰ and ultrasonic inspection qualification rate can achieve to 95% using the above process for the mass production.