TC4钛合金激光选区熔化成形性能研究

Study on TC4 Titanium Alloy Selective Laser Melting Forming Mechanical Properties

采用激光选区熔化(SLM)技术,使用北京隆源自动成型系统有限公司生产的AFS-M260金属快速成型机成功制备了Ti6Al4V(TC4)钛合金试件。为了研究不同激光功率和扫描速度对SLM成形TC4钛合金机械性能和显微组织的影响规律,利用扫描电子显微镜、万能拉伸试验机、Nikon ECLIPSE MA200金相显微镜等测试手段对SLM成形钛合金试件的断口形貌、显微组织及综合力学性能进行分析,结果表明,在合适工艺参数(P=300 W,v=1.5 m/s)条件下,成形试件的拉伸强度可达到1 227.13 MPa,伸长率至8.2%。严格控制成形气氛中杂质元素和氧含量有利于减少成形试件内部缺陷,提高机械性能。由于SLM成形过程中,显微组织不可避免会生成未熔合、小气孔等杂质相,造成塑性性能不高,为了进一步改善试件的塑性,采用SX-5-12型箱式热处理炉对试件进行热处理对比分析。实验表明,普通退火处理和再结晶退火处理方法都有利于改善材料的塑性性能,采用再结晶退火方法可以将伸长率提高19.6%,但拉伸强度被不同程度的削弱,而简单的固溶时效方法不能提高试样的伸长率,且强度略有下降。因此,采用再结晶退火+固溶时效的热处理方式,可以同时获得优良的合金强度和塑性性能,但对时效温度和固溶冷却速度还需要进一步研究。

Using selective laser melting technology（SLM）,the Ti6 Al4 Vtest specimens is successfully prepared with AFSM260 metal rapid prototyping machine by Beijing Longyuan AFS Co.Ltd.produced.In order to study the influence of different process parameters as laser power and scanning speed on mechanical properties and microstructure,using scanning electron microscopy,tensile testing machine,Nikon ECLIPSE MA200 metallographic microscope and other test methods,fracture morphology microstructure and mechanical properties were analyzed.The results show that in the appropriate process parameters（P=300 W,v=1.5 m/s）,the tensile strength can reach 1 227.13 MPa and elongation reach to 8.2%.Controlling the impurity elements and oxygen content in the forming atmosphere strictly is helpful to reduce the internal defects of the test specimens and improve the mechanical properties.Because the SLM forming process with incomplete fusion,small pore impurity phase were inevitably generated,resulting in lower plastic performance level.Using the SX-5-12 box type heat treatment furnace to analysis the influence of different heat treatment on improve the plastic performance.Experimental results show that both the ordinary annealing and recrystallization annealing treatment method can improve the performance of plastic performance,the recrystallization annealing method can increaseelongationof specimens by 19.6%,but the tensile strength are weakened in different levels,and simple solution ageing method can not increase the elongation of specimens,the tensile strength decreased slightly.Therefore,by using recrystallization annealing plus solution and aging heat treatment can help obtain excellent tensile strength and plastic properties,but the aging temperature and the cooling rate of solution needs further study.