机械工程学报
機械工程學報
궤계공정학보
CHINESE JOURNAL OF MECHANICAL ENGINEERING
2014年
21期
152-158
,共7页
增材制造%电子束%选区熔化%表面形貌%扫描方法
增材製造%電子束%選區鎔化%錶麵形貌%掃描方法
증재제조%전자속%선구용화%표면형모%소묘방법
additive manufacturing%electron beam%selective melting%surface topography%scanning method
电子束选区熔化是一种利用电子束逐层熔化金属粉末制造三维实体零件的增材制造技术，在航空航天、医学植入体等领域有很好的应用前景。利用316L不锈钢粉末为材料，研究粉末熔化阶段电子束功率恒定、单遍扫描对成形件上表面粗糙度的影响。发现电子束功率P与扫描速度v的比值是影响上表面形貌的关键因素，随着P/v值的增加，上表面形貌由网结状变化为沟壑状，同时粉末材料的飞溅增加。研究上表面形貌随成形高度增加而演变的过程，发现形貌随高度增加不断恶化，并解释了形貌恶化的原因。提出电子束功率递增、多遍扫描的方法，先用低功率电子束使粉末材料熔化聚球但不飞溅，再用大功率电子束使材料重新熔化并充分流动、浸润。这种方法改善了成形件上表面的形貌，表面粗糙度Ra小于8μm，获得的组织均匀细密，致密度高达99.96%。相对于单遍扫描，多遍扫描不会造成主要元素的额外烧损。
電子束選區鎔化是一種利用電子束逐層鎔化金屬粉末製造三維實體零件的增材製造技術，在航空航天、醫學植入體等領域有很好的應用前景。利用316L不鏽鋼粉末為材料，研究粉末鎔化階段電子束功率恆定、單遍掃描對成形件上錶麵粗糙度的影響。髮現電子束功率P與掃描速度v的比值是影響上錶麵形貌的關鍵因素，隨著P/v值的增加，上錶麵形貌由網結狀變化為溝壑狀，同時粉末材料的飛濺增加。研究上錶麵形貌隨成形高度增加而縯變的過程，髮現形貌隨高度增加不斷噁化，併解釋瞭形貌噁化的原因。提齣電子束功率遞增、多遍掃描的方法，先用低功率電子束使粉末材料鎔化聚毬但不飛濺，再用大功率電子束使材料重新鎔化併充分流動、浸潤。這種方法改善瞭成形件上錶麵的形貌，錶麵粗糙度Ra小于8μm，穫得的組織均勻細密，緻密度高達99.96%。相對于單遍掃描，多遍掃描不會造成主要元素的額外燒損。
전자속선구용화시일충이용전자속축층용화금속분말제조삼유실체령건적증재제조기술，재항공항천、의학식입체등영역유흔호적응용전경。이용316L불수강분말위재료，연구분말용화계단전자속공솔항정、단편소묘대성형건상표면조조도적영향。발현전자속공솔P여소묘속도v적비치시영향상표면형모적관건인소，수착P/v치적증가，상표면형모유망결상변화위구학상，동시분말재료적비천증가。연구상표면형모수성형고도증가이연변적과정，발현형모수고도증가불단악화，병해석료형모악화적원인。제출전자속공솔체증、다편소묘적방법，선용저공솔전자속사분말재료용화취구단불비천，재용대공솔전자속사재료중신용화병충분류동、침윤。저충방법개선료성형건상표면적형모，표면조조도Ra소우8μm，획득적조직균균세밀，치밀도고체99.96%。상대우단편소묘，다편소묘불회조성주요원소적액외소손。
Electron beam selective melting (EBSM) is an additive manufacturing technology that utilizes an electron beam to build three-dimensional object layer by layer from metal powder, and can be applied in manufacturing aerospace components and medical implants. Effect of the single-pass scanning with constant power on the top surface topography is studied by using the 316L stainless steel powder material. It’s found that the ratio of the electron beam power P to the scanning velocity v is the key factor affecting the top surface topography. With the increase of P/v, the top surface topography changes to a gully type from a balling-net type, and the spatters increase. The evolution of the top surface topography with the increase of the fabricated height is also studied. And it’s found that the topography worsens with the increase of the fabricated height. The reasons for the topography worsening are explained in detail. A multi-pass scanning process with progressively increasing power is developed, and it largely improves the top surface topography of the fabricated parts. The roughness Ra of the top surface is lower than 8μm. Uniform and fine microstructures can be obtained, and the relative density of the fabricated sample reaches up to 99.96%. Compared to the single-pass process, the multi-pass process does not cause additional melting loss of the elements.
