Effect of substrate structure on cutting performance of coated cemented carbide tools in milling cast iron

Effect of substrate structure on cutting performance of coated cemented carbide tools in milling cast iron

b e t w e e n c o a t i n g a n d s u b s t r a t e s were e x a m i n e d by electron microscopy. Laaice o r i e n ~ t i o n relanonships, a n d mism...

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b e t w e e n c o a t i n g a n d s u b s t r a t e s were e x a m i n e d by electron microscopy. Laaice o r i e n ~ t i o n relanonships, a n d mismatches b e ~ v e e n c o a t i n g a n d s u b s t r a t e s were d e t e r m i n e d , a n d c o a t i n g s h o w n to be epitaxial with t h e substrates.

decrea~.~:~ ~ t ~ F-.Se in ?emperar.ure. Three p h a s e ~!oys have iow~r t h e ~ a i di~isi~i~¢ t h a n v-,vo ph:~e, Increase in %Co reduces t h e r m ~ diffusiviF~'. Four ~ha~a WC-TiCTaC-Co aiioys have m u c h lower t h e ~ a l diffusi~fft3" t h a n wvo p h a s e WC-Co.

an increase in the % TiC. A tool containing 20-30% TiC of fine grain size gave o p t i m u m cutting performance in m a c h i n i n g an alloy steel with improved resistance to flaking. M ~ h a n i s m s of flank wear a n d flaldng are discussed.

ZrO S T R E N G T H .~N'D PLASTICITY ( I I ) ZrC D E F O R M A T I O N STRUCTURE

P R O P E R T I E S :~ND : ~ P L I C A T I O N S OF DL-kMOND-LIK~ CARBON ( D L C ) COATrNGS

N~EW HARD METAL GIk4DES DESIGN~ED FOR ROLLS

A G Lanin, et at, (Research Technological Institute, Podolsk, USSR), Int J. Refractory $Ietals & Hard Ma~tvrials, Vol 9, No 3, 1990, 139-142. T h e m o r p h o l o g y , of ZrC a n d t h e development of plastic deformation t h e r e i n w e r e s t u d i e d . M e c h a n i s m s of carbide deformation at different t e m p e r a t u r e s are suggested. The essential differences in t h e deformation beha~4our of carbides a n d metals are discussed. STUDY O F T H E D E C O M P O S I T I O N O F TiC-WC SOLID SOLUTIONS S Zhenhui, (Zhuzhou Cemented Carbide Industry Co, Hunan, China), Int J. Refractory Metals & Hard Materials, Vol 9, No 3, 1990, 154-156. The decomposition of the TiC-WC solid solution, used in the p r o d u c t i o n of h a r d metals, was studied by X-ray diffraction a n d microscopy. It was found t h a t t h e solid solution decomposes during c o m m i n u t i o n t r e a t m e n t a n d in t h e presence of a liquid p h a s e d u r i n g sintering. CHEMICAL VAPOUR D E P O S I T E D (CVD) CHROMIUM CARBIDE COATINGS ON WC-Co HARD METALS AND HOT WORK STEEL

C Wohlrab, et al, (Technical University, Vienna, Austria), Int J. Refractory Metals & Hard Materials, Vol 9, No 3, 1990, 157-166. In German. Chromium carbide coatings were applied to WC-Co h a r d m e t a l s a n d to h o t work steel by CVD. Reactions b e t w e e n coating a n d s u b s t r a t e s were e x a m i n e d as a function of deposition p a r a m e t e r s by optical a n d e l e c t r o n microscopy, X-ray diffraction a n d energy dispersive analysis. Distribution of elements across t h e interface yeas measured. The p h a s e s observed were c o m p a r e d w i t h d a t a from p h a s e d i a g r a m s d e d u c e d from thermocbynamic data. Oxidation tests were carried out to assess high t e m p e r a t u r e performance. THERbLA:L DIFFUSIVITY O F HARD METALS Z Li, et al, (Powder Metallurgy Factory, Changsha, Hunan, China), Int J. Refractory Metals & Hard Materials, Vol 9, No 3, 1990, 167-169. A l a s e r f l a s h m e t h o d was used to m e a s u r e t h e r m a l diff~siviw of WC-Co a n d WC-TiC-TaC-Co. It is s h o w n t h a t t h e thermal d i f f u s i v i t y o f W C - 1 0 % Co

J Franks, e t a ! , (Ion Tech Ltd, Teddington, Middlesex, UK), Metals and Materials, Vol 6, No 11, 1990, 695-700. The p a p e r describes t h e d e p o s i t i o n , properties a n d applications of DLC films on to a range of different materials. The ¥Sckers h a r d n e s s of DLC is in the range 2000-9000, compared with diamond > 10 000. DLC a d h e r e s well to metallic s u b s t r a t e s a n d has a low coeflicient of friction. Applications include coatings on cutting tools which are not subjected to high t e m p e r a t u r e a n d bearing parts. E F F E C T OF SUBSTRATE S T R U C T U R E ON C U T T I N G P E R F O R M A N C E O F COATED C E M E N T E D CARBIDE TOOLS IN MILLING CAST IRON K Kobofi, et al, J. Japan Soc.Powdvr and Powder" Metallurgy, Vol 37, No 4, 546-550. In Japanese. C e m e n t e d carbide tools were coated with a layer of TiC 2 l~m in thickness. The tool life in milling a ductile cast iron ~ s investigated with respect to t h e carbide grain size in t h e substrate. It ~ a s found t h a t tool life increased as t h e carbide grain size was reduced.

P R O P E R T I E S O F WC-TLN-Co ALLOYS N Tsuchiya, et al, J. Japan Soc. Powdvr and Powder Metallurgy, Vol 3, No 4, 562-565. In Japanese. Microstructure a n d properties of WCTiN-Co were m e a s u r e d a n d c o m p a r e d with t h o s e of WC-TiC-Co using 0-15% TiC or TLN a n d 10% Co. There was m u c h tess solid solution in t h e nitride alloys t h a n in t h e carbide alloys. The nitride alloy h a d h i g h e r s t r e n g t h a n d lower h a r d n e s s t h a n t h e carbide alloy.

E F F E C T S O F TiC C O N T E N T AN-I) GRAIN SIZE ON T H E C U T T I N G P E R F O R M A N C E O F TiC,-AI203 C U T T I N G TOOL MATERIALS Y Katsumura, et al, J.Japan Soc. Pawcl~r and Pmvder Metallurgy, Vol 37, No 4, 566570. In J a p a n e s e . The cutting performance of Alz03-0 to 50% TiC, h o t pressed cutting tools was assessed. Flank wear in m a c h i n i n g grey cast iron was reduced by reduction in the %TiC a n d increasing its grain size. In the case of ductile cast iron, flank wear was reduced by

T K a r w a t a , J Bujok, ( H u t a B a i l d o n , Katowice, Poland), Metalturcfia Proszkow, No 2, 1990, 55-57. In Polish. Production a n d characteristics of coarse grain sized h a r d metal grades are described. It is suggested t h a t these give improved p e r f o r m a n c e in r o l l s w i t h e c o n o m i c ad~"antage. STRUCTURE AND PROPERTIES OF A Co-FREE HIGH S P E E D STEEL - ATOMIZED ANrD HIPed

A S Fareed, et al, (Lanxide Corporation, Newark, Delaware, USA), [nt J. Powder Metallurgy, Vol 26, No 4, 1990, 351-365. The m i c r o s t r u c t u r e of REX25 HSS (Fe1.8%C-3%Cr- 13.3%W-4.6%V-6.5%Mo) p r e p a r e d from gas a t o m i z e d a n d HIP consolidated powder was characterized. In atomized condition MC a n d M2C carbides in a f e r r i t i c m a t r i x w e r e o b s e r v e d . On annealing, M2C decomposes to M6C. After HIPing, MC, M6C a n d M2~C6 carbides in a ferritic matrix are observed. Carbide volume fractions are i n d e p e n d e n t of prior p a r t i c l e size a n d / o r HIP t e m p e r a t u r e . Increase of HIP t e m p e r a t u r e leads to a coarsening of t h e structure. STRUCTURE AND PROPERTIES OF A HEAT T R E A T E D Co-FREE HIGH S P E E D STEEL

A S Fareed, et al, (Lanxide Corporation, Newark, Delaware, USA), Int J. Powder Metallurgy, Vol 26, No 4, 1990, 367-381. Processing and structure/property r e l a t i o n s h i p s have been e s t a b l i s h e d for h e a t t r e a t e d PM REX25 with regard to HIP conditions a n d austenitizing temperature. Austenite grain size is i n d e p e n d e n t of prior particle size b u t d e p e n d s on b o t h HIP a n d austenitizing temperature. Carbides p r e s e n t a n d carbide particle size were studied. Bend a n d impact s t r e n g t h s were increased by forging a n d low austenitizing t e m p e r a t u r e s . F r a c t u r e was seen to be initiated at c a r b i d e / m a t r i x interfaces. STRUCTURE DEVELOPMENT IN TiN-Ni ALLOYS

F F Egorov, et al, Poroskavaya Metalturgia, No 4, 1990, 25-30. In Russian. Development of microstructures in TiNNi alloys which have been high t e m p e r a t u r e liquid p h a s e sintered a n d low t e m p e r a t u r e solid p h a s e sintered are investigated. U n d e r liquid p h a s e sintering the TiN is depleted of N2, Ti is dissolved in the Ni m a t r i x a n d TiNi

MPR January 1991 53