激光成形工艺对TB18钛合金微观组织的影响

Effects of Laser Forming on Microstructure of TB18 Titanium Alloy

采用BLT-C1000型SLM增材制造设备进行了TB18钛合金激光立体成形,通过3因素3水平正交试验法研究了激光功率、扫描速度、送粉率对单道沉积层和块体微观组织、形貌特征的影响,并优化了成形工艺参数。结果表明,单道沉积层柱状晶组织特征,随扫描速度和激光功率增大、送粉率降低,单道沉积层宽高比增大,对宽高比影响程度依次为扫描速度>激光功率>送粉率。块体微观组织均为双态组织,提高扫描速度,合金组织由α+β相分明的双态组织向次生α相均匀分布在β基体的组织特征转变。从获得良好组织考虑,成形工艺参数应采取扫描速度为800~1000 mm/min、激光功率为3.0~3.5 kW、送粉率为25~30 g/min适宜。

Laser solid forming of TB18 titanium alloy was carried out by BLT-C1000 SLM additive manufacturing equipment.The effects of laser power,scanning speed and powder feeding amounts on the microstructure and morphology characteristics of single channel deposition layer and block were investigated by three-factor and three-level orthogonal test method,and the forming parameters were optimized.The results indicate that the single channel deposition layer is characterized by columnar grain,and the width to height ratio is increased with the increase of scanning speed and laser power and the decrease of powder feeding amount,of which the influence degree is in the sequence of scanning speed>laser power>powder feeding amounts.The microstructure of the block is characterized by two-state.With the increase of scanning speed,the microstructure of the alloy is transformed from the two-state microstructure with distinctα+βphase to that with uniform distribution of secondaryαphase in theβmatrix.In order to obtain desirable microstructure,the optimal parameters of forming process is scanning speed of 800~1000 mm/min,laser power of 3.0~3.5 kW and powder feeding rate of 25~30 g/min.