聚晶金刚石刀具铣削Ti40阻燃钛合金失效机理

Failure Analysis of PCD Tools in Milling Ti40 Burn-Resistant Titanium Alloy

选用3种不同粒度金刚石（0.5,10和30μm）的聚晶金刚石（Polycrystalline diamond,PCD）刀具铣削加工Ti40阻燃钛合金,结合三维视频显微镜与扫描电镜观测刀具形貌,分析金刚石粒度对刀具磨损和破损行为的影响,揭示PCD刀具的失效机理。研究发现,金刚石粒度越小,PCD刀具的耐用度越高。在铣削加工的力-热冲击作用下,PCD刀具的磨损主要表现为磨粒磨损和粘结磨损,而破损初期表现为以微裂纹、前后刀面剥落和微崩刃为主,后期发生了局部碎裂。剥落和微崩刃主要发生在PCD刀具的前、后刀面临界切深2.5~3.0mm处,微裂纹是导致发生剥落和微崩刃的主要因素。

Milling experiments of Ti40burn-resistant titanium alloy are performed using three kinds of polycrystalline diamond（PCD）tools with various diamond grain sizes（i.e.,0.5,10 and 30μm）.The morphology of PCD tools after milling is observed using three-dimensional optical microscope and scanning electron microscopy.Failure mechanisms of PCD tools and their relation between various diamond grain sizes and tool wear are analyzed.The results indicate that the PCD tool life is longer when the contained diamond grain size is smaller.With the mechanical-thermal effects during milling,abrasion and adhesion are the main wear mechanisms of PCD tools.However,the main fracture mechanisms are micro-crack,micro-chipping and spalling of rake face and flank face,which usually take place at the position with a critical depth（i.e.,2.5—3.0mm）in the initial wear stage.Local fragmentation occurs in the latter wear stage.Micro-cracks are the main factor leading to micro-chipping and spalling of tool rake face and flank face.