激光选区熔化成形ZK61工艺及组织性能研究.docx

激光选区熔化成形ZK61工艺及组织性能研究摘要：镁合金因其密度小、比强度高等优点被广泛应用于汽车、航空航天等领域，是当今绿色制造的首选材料。激光选区熔化(Selectivelasermelting,SLM)技术在制造性能优异、结构复杂的镁合金零部件方面有巨大的潜力。本文以ZK61高强镁合金为实验材料，研究了基板材质对ZK61成形性能的影响、SLM工艺参数对ZK61成形样致密度的影响、优化SLM参数成形样的组织和力学性能。结果表明：SLM成形ZK61镁合金对基板材质要求严格，须采用成分大致相同、润湿性好的基板。ZK61成形窗口窄，成形件相对致密度对SLM参数比较敏感，在最优参数下可成形出相对致密度高达99.3%的试样。在SLM成形快速冷却的作用下，ZK61合金中β'(Mg0.97Zn0.03)替换了常规的β(MgZn)相，晶粒尺寸仅为铸造ZK61的1/25。SLM成形ZK61镁合金显微硬度为100HV左右，约比铸造ZK61高出40%；在孔洞缺陷制约下，SLM成形ZK61镁合金的压缩性能与轧制ZK61性能有一定差距。关键词：激光选区熔化；ZK61；工艺优化；组织性能TG146；V19StudyonProcessandMicrostructureandPropertiesofZK61AlloyfabricatedbyLaserSelectiveMeltingYuanHongwei(GuizhouAerospaceFenghuaprecisionequipmentCo.,Ltd,GuizhouGuiyang,550009)Abstract:Magnesiumalloyhasbeenwidelyusedinautomotive,aerospaceandotherfieldsduetoitslowdensityandhighspecificstrength,andisthepreferredmaterialforgreenmanufacturing.SelectiveLasermelting(SLM)hasgreatpotentialinfabricatingmagnesiumalloypartswithexcellentperformanceandcomplexstructure.Inthispaper,ZK61highstrengthmagnesiumalloywasusedasexperimentalmaterialtostudytheinfluenceofsubstratematerialonthefabricatingperformanceofZK61,theinfluenceofSLMprocessparametersonthedensityofZK61.MicrostructureandmechanicalpropertiesofZK61fabricatedbySLMwithoptimizationparameterswereanalyzed.TheresultsindicatedthatSLMformingZK61alloyhasstrictrequirementsonthesubstrate,andsubstratewithroughlythesamecompositionandgoodwettabilitywasrequired.TheSLMformingwindowofZK61wasnarrow,andtherelativedensityoftheformingpartwassensitivetoSLMparameters.Undertheoptimalparameters,specimenswiththerelativedensityupto99.3%canbeformed.Duetorapidcooling,theconventionalβ(MgZn)phasewasreplacedbyβ'(Mg0.97Zn0.03)phaseinSLMZK61alloy,andthegrainsizeofSLMZK61alloywasonly1/25ofthatofthecastZK61.ThehardnessofZK61alloyfabricatedbySLMwasabout100HV,whichwasabout40%higherthanthatofcastingZK61.Duetotherestrictionofholedefects,therewasagapbetweenthecompressionpropertiesofSLMZK61alloyandthatofrollingZK61.Keywords:selectivelasermeltingZK61processoptimizationmicrostructurea