A review of processing science of additive manufacturing(AM)(增材制造工艺综述)

A review of processing science of additive manufacturing(AM)

on metal

Y. P. Ren

Additive manufacturing(AM),known by people as 3D printing,is a manufacturing method which using a computer controlled laser form component layer by layer from powder,sheets or wire.additive manufacturing(AM) has grown and developed prosperous in the past decades years,many techniques such as:SLM,SLS,LOM,LENS,FDM,SLA have been developed to manufacturing complex shaped functional metallic components,which also has tremendously potential in the area of aerospace, defence,bio-medical industries and automotive.In this review,the processing science of metal manufacturing is focused,the follow parts will be explore d:the theory of metal AM techniques,processing defects,solidification,solid-state precipitation,mechanical properties and post-processing.the present review has established the relation between metallurgical mechanism,material and process for laser based AM,furthermore,the more processing techniques will be discussed more detailed in this review.

Keywords:Additive manufacturing, Processing science, Metals

Introduction

Additive manufacturing (AM),known by people as three dimensional (3D) printing,has developing for decades years since 1980s and becoming one of the most advanced manufacture techniques over the world.though there still are several problems limit the application of AM,the processing and materials both face unique issues.understanding the processing of various techniques and dilemma will be help for improving the capabilities of the components.

The earliest patented process relevant to metal AM is selective laser sintering (SLS),which form parts from mixed metal and polymer powder.the first reported metal AM part was manufactured in 1990 by Bourell and Manriquez-Frayre form metal alloy powders (Manriquez-Frayre, 1990).it is significant though the mechanical property and quality is far from application.A new process was patented by EOS GnbH,which can full melting the metal powder,called selective laser melting (SLM).SLM is widely used to make metal parts at now,many companies such as 3D Systems,Optomec have entered this market with laser powder-bed hardware and software for metal production.another process called “three dimensional printing”was patented by a group of researches at MIT,and now we named it Binder Jetting,which

can be used for form metal parts and other materials.The name of “3D printing”has been used to described all kind of AM.Inspired by selective melting of a powder bed,some researches innovated the direct energy deposition (DED),which deposit feed-stock directly into a molten pool.The LENS was the first commercialised DED technology developed by Sandia National Laboratories In 1995.Sheet lamination,the last category of metal AM patented by Dawn White of Solidica in 1999,which uses ultrasonic welding technology and computer numerical control (CNC)form 3D parts.At the start of this century,another metal AM technology:electron beam melting (EBM) patented by Sweden,which also use power-bed feed-stock.

AM technology has been widely used for Rapid prototyping (RP) and rapid manufacturing(RM) (Gu, 2015).Applied at the area of aerospace structures,Part repairs,biomedical implants and high temperature components.but there still have big questions need to discuss ,especially for the processing science.The basic purpose of this essay is to review the current situation of research and development of metal AM. Classification of AM technologies

The category of AM technology diverse from metal to polymer,materials changes from powder to sheet,the mew techniques developed more and more.While,both of them must consolidate the feed-stock into a dense part,form the component layer by layer.For the purpose of discuss distinct classes of machines,the ASTM F42 Committee of Additive Manufacturing has released a standard on process terminology (ASTM, 2012).There are four categories to metal AM:

●Powder bed fusion (PBF)

➢Selective laser melting (SLM)

➢Electron beam melting (EBM)

●Direct energy deposition (DED)

➢Laser vs.e-beam

➢Wire fed vs.powder fed

●Binder jetting

➢Infiltration

➢Consolidation

●Sheet lamination

➢Ultrasonic additive manufacturing (UAM) (Sames, 2015)

In this review,we will focus on PBF and DED,these two kinds of AM technology were widely used to manufacture metal parts.Both two could achieve highly quality micro-structure and mechanical property.