The Study Of Preparation And Formability Of TC21 Titanium Alloy Powder For Laser 3D Printing

3D printing technology developed fast in recent years,metal laser 3D printing as the most advanced laser technology in the 3D printing system,widely used in astronavigation,automobile,ship,medical equipment and other fields,and titanium alloy is one of the most widely used metal materials in laser 3D printing aircraft parts.The characteristics of titanium alloy powder for laser 3D printing is the key factor to the quality of forming products,now the high performance laser 3D printing titanium alloy powder used in our country is mostly imported from abroad.Therefore,it has great values both on scientific research and practical applications to study on preparing key technologies of high performance titanium alloy powder for laser 3D printing with independent intellectual property rights.In this paper,the TC21 titanium alloy powder was prepared by electrode induction melting gas atomization(EIGA)equipment,chemical composition,morphology,phase,microstructure,hollow powder rate,particle size,fluidity,bulk density and formability of laser 3D printing of the powder were systematically studied with optical microscopy(OM),scanning electronic microscopy(SEM),X-Ray diffraction(XRD),nitrogen hydrogen oxygen analyzer,laser scattering particle size distribution analyzer,hall flowmeter and bulk density meter and other means of detection.The results are as follows:TC21 titanium alloy powder was successfully prepared under the optimized parameters(power is 65kW and gas pressure is 6MPa).The morphology of the powder is mainly spherical,particle size is between 1?180?m,oxygen content is 0.1%,the bulk density and fluidity of the 54-180?m powder is 2.77g/cm3 and 21.19s/50g,hollow powder rate is less than 3%;The surface structure of the powder is mainly dendrite and a small amount of cellular crystal crystals,the internal structure of the powder is dendrite;the main phases of powder are ?',? and intermetallics such as AlTi3,Ti2AlNb,Zr3Al.TC21 titanium alloy deposited samples were successfully printed,under the optimized laser 3D printing parameters:send powder flow is 4L/min,powder feeding rate is 6.4r/min,current is 155A,frequency is 50Hz,pulse width is 1.1ms,scanning speed is 4mm/s,Z offset is 0.4mm.Microstructure of deposited samples was composed of ? columnar crystal,which grown along deposited direction and was through multiple deposited layers,and phases are ?',? and intermetallics of AlTi3,Ti2AlNb,Zr3Al.Microstructure of deposited samples can be divided into three parts of light area,transitional area and dark area,light area consisted of ?'martensite needles and dark area consisted of basketweave structure;microhardness of this two regions were 541HV and 470HV;Ultimate tensile strength of deposited samples can reach 1150MPa and elongation was about 8%.Thus,the TC21 titanium alloy powder prepared by the method has good laser 3D printing formability.