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Analysis of impact forging of porous bodies
A model has been suggested of L,he effe-,t of porosity on crack initiation in low c~v!e fatigue. Ti was used tbr e x p e r i m e n t a l w o r k It was a s s u m e d t h a t porosiD- located a t the surface can be s i m u l a t e d ms a through. thickness hole under plane stress conditions. The model permits the p r e d i c t i o n of t h e n u m b e r of cTcles to m i c r o c r a c k i n i t i a t i o n in p r e s e n c e ,)f porosity. The prediction compares favourably with the m e a s u r e d n u m b e r of cycles to initiate a 15 p m crack a d j a c e n t to isolated a n d interconnected pores.
ROLLING CON"rACT F A T I G U E T E S T ~ ' G OF PM HIGH S P E E D S T E E L S (HSS) J A W h i t e h e a d , et al. ( P o w d r e x Ltd, T o n b r i d g e , Kent, UK), [nt J. Powder Metalluwy, Vol 26, No 4, t990, 345-349. A test rig for t h e evaluation of roiling c o n t a c t fatigue isdescribed. Application to s i n t e r e d tool steels a n d sintered m i x t u r e s of HSS a n d low alloy steels provides a basis lbr u n d e r s t a n d i n g failure m e c h a n i s m s in rolling c o n t a c t fatigue a n d t h e role of porosity.
AN.~LYSIS OF IMPACT F O R G I N G O F POROUS BODIES M S Kovalchenko, Poroskcrvaya MetaUury/a, No 4, 1990, 5-7. In Russian. I m p a c t hot forging of porous material h a s been analysed m a t h e m a t i c a l l y for t h e conditions of p l a n e tooling. Correlations between i m p a c t force and speed, specimen size a n d relative density have been found.
ANALYSIS O F HYDROMECHANICAL U P S E T T I N G O F A POROUS BILLET V S Tyutenko, et al, Poroskovaya Metallurg/a, No 4, 1990, 8-11. In Russian. High s p e e d steel billets h a v e b e e n d e f o r m e d by s i m u l t a n e o u s uniaxial compression and application of hydrostatic pressure. The process h a s been analysed mathematically. It is shown t h a t t h e billet porosiW after hydromechanical u p s e t t i n g is d e t e r m i n e d by t h e lateral p r e s s u r e applied. C H E M I C A L AND PHASE TRANSFORMATIONS DURING R E D U C T I O N O F W-Co COI~POUNDS A S Petukhov, Poroskovaya Metallurgia, No 4, 1990, 35-39. In Russian. ]'he reduction of complex W-Co oxide ~ ' s t e m s in H2, CH4 a n d solid C has been investigated in t h e t e m p e r a t u r e range 300II00~C with respect to t h e thermod:y~aamic relationships involved. It has been shown t h a t cobalt t u n g s t a t e has high stability within the p a r a m e t e r s studied. It has also
bee~ shc~',~T: t,~ be p,.,ssib[e to reduce rand carbur'z~o oxid~ mixhares both by CH4 and so :.:id ¢-arb,-_,n. E F ~ C T OF MORPHOLOGY OF POWDER PzMRTICLES ON P R O P E R T I E S OF POROUS ~L~TERLa.LS V M Kaptsev':ch, et al, P o r o s k o v a y a 3Ietallu(¢ia, No 4, t990, 62-68. In Russian. Properties of porous materials formed from powders of s h a p e factor 0.22 to 1.0 have been investigated_ Effects of powder p a r t i c l e s h a p e on p o r e s h a p e , sizes, permeabiliD ~ a n d effect on capillaD" flow have been established. It is shown t h a t as t h e s h a p e f a c t o r d i m i n i s h e s , so d o e s permeability, a n d capillaD' flow increases.
P H A S E DIAGR.~I F O R T H E S Y S T E M CrHfC
S V Sleptsov, A A Bondar, Poroskavaya ,Iletatlurg/a, No 4, 1990, 76-80. In Russian. D i f f e r e n t i a l t h e r m a l analysis, X-ray diffraction and spectroscopy and metallographic analysis have been used to investigat p h a s e relationships in Cr-Hf-C alloys. Phase b o u n d a r i e s a n d limits of solubility have been determined.
PRODUCTS: Aiuminium
POWDER FORGLNG OF RAPIDLY SOLIDIFIED ( R S ) AI ALLOY POWDERS ANq) MECHANICAL PROPERTIES OF PARTS PRODUCED
M Ohtsuki, et al, J.Japan Soc. Powder and Pmr,der Metallurgy, Vol 37, No 4, 1990, 513520. In Japanese. The m e c h a n i c a l p r o p e r t i e s of p a r t s p r o d u c e d from RS / d alloy powders by powder forging were investigated. It was found t h a t for a n Al-18%Si alloy which h a d been rigid h o t die coined a n d hot forged the p r o p e r t i e s w e r e as good as t h o s e of e x t r u d e d m a t e r i a l . The forging of AI25%Si-3%Cu-l%Mg-l%Fe a n d Al-10%Fe1.5%Mo-l%Valloys also gave p r o p e r t i e s equal to those of e x t r u d e d materials. It was sho~-a t h a t powder forging gave good yields of products, with cost s a ~ n g s a n d a reduced need for machining. PROPERTIES ANq) APPLICATIONS O F RAPIDLY S O L I D I F I E D ( R S ) A1 POWDER ALLOY WITH LOW THERMAL EXPANSION .4~N'D HIGH ELASTIC MODULUS
H Inoue, S O K Yoshikawa, (Materials R e s e a r c h Laboratory., Kobe Steel Ltd, Kobe, Hyogo, J a p a n ) , Kobetco Technology Rewiew, No 8, 1990, 47-50. The applications of p a r t s m a d e from RS AI-Si powders are discussed. Structure, properties a n d applications of alloys with up to 35% Si are considered. The alloys are
s h o ~ to have high specific modulus, low t h e ~ a l e x p a n s i o n a n d good machinabili~-. LNTLUENCE OF OXIDES ON T H E P R O P E R T I E S O F PM At-Li-Cu ALLOYS T S Srivatsan, et al, (University of Akron, . ~ o n , Obdo, USA), Int J. Pawder Metalhtmyy, Vol 26, No 4, 1990, 321-334. The formation of oxides, carbonates a n d oxide films during production of rapidly. solidified (RS) .aA-IA-Cu powders has been i n v e s t i g a t e d w i t h r e f e r e n c e to a l l o y evaporation, environment and metal/ e n ~ o n m e n t interactions. Effects of oxides etc. on mechanical properties are examined, in particular t h e d e t r i m e n t a l e f f e c t s of o x i d e s t r i n g e r s . P o s s i b l e i m p r o v e m e n t s in processing technique are discussed. Comparisons are m a d e between PM m a t e r i a l s a n d c a s t a n d w o r k e d materials to highlight the effects of oxides etc. on mechanical properties.
Chromium I
I
M
.......
STRUCTURE AND PROPERTIES OF SLNTERED Cr
I O A n d r u s h c h i k , et al, Poroskovaya Metalluwia, No 3, 1990, 34-39. In Russian. Powdered Cr compacts were sintered by e l e c t r o c o n t a c t h e a t i n g a n d c h a n g e s in ~ r u c t u r e a n d properties measured. It is said t h a t most change takes place during rapid heating to the sintering t e m p e r a t u r e a n d t h e r e are only small changes during the s u b s e q u e n t i s o t h e r m a l h e a t i n g period. Rapid heating to 1400°C a n d holding for five m i n u t e s are said to be the o p t i m u m sintering conditions giving minimal porosity a n d incidence of defects. REFINING ADDITIVES FOR PM Cro BASED ALLOYS
A N Volchkov, et al, Poroskovaya Metallurg/a, No 3, 1990, 44-46. In Russian. Thermodynamic analysis has been used to determine the most promising interstitial impurities and refining additives for use in PM Cr-based alloys. The required a m o u n t s of a d d i t i o n s have been calculated.
Copper
~,[ECtIANIC.4oL AND PHYSICAL PROPERTIES OF Cu-Mo ALLOYS A G Kostornov, V P Semenets, Poroskovaya Metallurgia, No 4, 1990, 59-62. In Russian. Cu-Mo alloys were produced by pressing followed by either solid or liquid p h a s e sintering. The properties of t h e solid p h a s e sintered specimens d e p e n d e d mainly on the
MPR January 1991 51
ROLLING CON"rACT F A T I G U E T E S T ~ ' G OF PM HIGH S P E E D S T E E L S (HSS) J A W h i t e h e a d , et al. ( P o w d r e x Ltd, T o n b r i d g e , Kent, UK), [nt J. Powder Metalluwy, Vol 26, No 4, t990, 345-349. A test rig for t h e evaluation of roiling c o n t a c t fatigue isdescribed. Application to s i n t e r e d tool steels a n d sintered m i x t u r e s of HSS a n d low alloy steels provides a basis lbr u n d e r s t a n d i n g failure m e c h a n i s m s in rolling c o n t a c t fatigue a n d t h e role of porosity.
AN.~LYSIS OF IMPACT F O R G I N G O F POROUS BODIES M S Kovalchenko, Poroskcrvaya MetaUury/a, No 4, 1990, 5-7. In Russian. I m p a c t hot forging of porous material h a s been analysed m a t h e m a t i c a l l y for t h e conditions of p l a n e tooling. Correlations between i m p a c t force and speed, specimen size a n d relative density have been found.
ANALYSIS O F HYDROMECHANICAL U P S E T T I N G O F A POROUS BILLET V S Tyutenko, et al, Poroskovaya Metallurg/a, No 4, 1990, 8-11. In Russian. High s p e e d steel billets h a v e b e e n d e f o r m e d by s i m u l t a n e o u s uniaxial compression and application of hydrostatic pressure. The process h a s been analysed mathematically. It is shown t h a t t h e billet porosiW after hydromechanical u p s e t t i n g is d e t e r m i n e d by t h e lateral p r e s s u r e applied. C H E M I C A L AND PHASE TRANSFORMATIONS DURING R E D U C T I O N O F W-Co COI~POUNDS A S Petukhov, Poroskovaya Metallurgia, No 4, 1990, 35-39. In Russian. ]'he reduction of complex W-Co oxide ~ ' s t e m s in H2, CH4 a n d solid C has been investigated in t h e t e m p e r a t u r e range 300II00~C with respect to t h e thermod:y~aamic relationships involved. It has been shown t h a t cobalt t u n g s t a t e has high stability within the p a r a m e t e r s studied. It has also
bee~ shc~',~T: t,~ be p,.,ssib[e to reduce rand carbur'z~o oxid~ mixhares both by CH4 and so :.:id ¢-arb,-_,n. E F ~ C T OF MORPHOLOGY OF POWDER PzMRTICLES ON P R O P E R T I E S OF POROUS ~L~TERLa.LS V M Kaptsev':ch, et al, P o r o s k o v a y a 3Ietallu(¢ia, No 4, t990, 62-68. In Russian. Properties of porous materials formed from powders of s h a p e factor 0.22 to 1.0 have been investigated_ Effects of powder p a r t i c l e s h a p e on p o r e s h a p e , sizes, permeabiliD ~ a n d effect on capillaD" flow have been established. It is shown t h a t as t h e s h a p e f a c t o r d i m i n i s h e s , so d o e s permeability, a n d capillaD' flow increases.
P H A S E DIAGR.~I F O R T H E S Y S T E M CrHfC
S V Sleptsov, A A Bondar, Poroskavaya ,Iletatlurg/a, No 4, 1990, 76-80. In Russian. D i f f e r e n t i a l t h e r m a l analysis, X-ray diffraction and spectroscopy and metallographic analysis have been used to investigat p h a s e relationships in Cr-Hf-C alloys. Phase b o u n d a r i e s a n d limits of solubility have been determined.
PRODUCTS: Aiuminium
POWDER FORGLNG OF RAPIDLY SOLIDIFIED ( R S ) AI ALLOY POWDERS ANq) MECHANICAL PROPERTIES OF PARTS PRODUCED
M Ohtsuki, et al, J.Japan Soc. Powder and Pmr,der Metallurgy, Vol 37, No 4, 1990, 513520. In Japanese. The m e c h a n i c a l p r o p e r t i e s of p a r t s p r o d u c e d from RS / d alloy powders by powder forging were investigated. It was found t h a t for a n Al-18%Si alloy which h a d been rigid h o t die coined a n d hot forged the p r o p e r t i e s w e r e as good as t h o s e of e x t r u d e d m a t e r i a l . The forging of AI25%Si-3%Cu-l%Mg-l%Fe a n d Al-10%Fe1.5%Mo-l%Valloys also gave p r o p e r t i e s equal to those of e x t r u d e d materials. It was sho~-a t h a t powder forging gave good yields of products, with cost s a ~ n g s a n d a reduced need for machining. PROPERTIES ANq) APPLICATIONS O F RAPIDLY S O L I D I F I E D ( R S ) A1 POWDER ALLOY WITH LOW THERMAL EXPANSION .4~N'D HIGH ELASTIC MODULUS
H Inoue, S O K Yoshikawa, (Materials R e s e a r c h Laboratory., Kobe Steel Ltd, Kobe, Hyogo, J a p a n ) , Kobetco Technology Rewiew, No 8, 1990, 47-50. The applications of p a r t s m a d e from RS AI-Si powders are discussed. Structure, properties a n d applications of alloys with up to 35% Si are considered. The alloys are
s h o ~ to have high specific modulus, low t h e ~ a l e x p a n s i o n a n d good machinabili~-. LNTLUENCE OF OXIDES ON T H E P R O P E R T I E S O F PM At-Li-Cu ALLOYS T S Srivatsan, et al, (University of Akron, . ~ o n , Obdo, USA), Int J. Pawder Metalhtmyy, Vol 26, No 4, 1990, 321-334. The formation of oxides, carbonates a n d oxide films during production of rapidly. solidified (RS) .aA-IA-Cu powders has been i n v e s t i g a t e d w i t h r e f e r e n c e to a l l o y evaporation, environment and metal/ e n ~ o n m e n t interactions. Effects of oxides etc. on mechanical properties are examined, in particular t h e d e t r i m e n t a l e f f e c t s of o x i d e s t r i n g e r s . P o s s i b l e i m p r o v e m e n t s in processing technique are discussed. Comparisons are m a d e between PM m a t e r i a l s a n d c a s t a n d w o r k e d materials to highlight the effects of oxides etc. on mechanical properties.
Chromium I
I
M
.......
STRUCTURE AND PROPERTIES OF SLNTERED Cr
I O A n d r u s h c h i k , et al, Poroskovaya Metalluwia, No 3, 1990, 34-39. In Russian. Powdered Cr compacts were sintered by e l e c t r o c o n t a c t h e a t i n g a n d c h a n g e s in ~ r u c t u r e a n d properties measured. It is said t h a t most change takes place during rapid heating to the sintering t e m p e r a t u r e a n d t h e r e are only small changes during the s u b s e q u e n t i s o t h e r m a l h e a t i n g period. Rapid heating to 1400°C a n d holding for five m i n u t e s are said to be the o p t i m u m sintering conditions giving minimal porosity a n d incidence of defects. REFINING ADDITIVES FOR PM Cro BASED ALLOYS
A N Volchkov, et al, Poroskovaya Metallurg/a, No 3, 1990, 44-46. In Russian. Thermodynamic analysis has been used to determine the most promising interstitial impurities and refining additives for use in PM Cr-based alloys. The required a m o u n t s of a d d i t i o n s have been calculated.
Copper
~,[ECtIANIC.4oL AND PHYSICAL PROPERTIES OF Cu-Mo ALLOYS A G Kostornov, V P Semenets, Poroskovaya Metallurgia, No 4, 1990, 59-62. In Russian. Cu-Mo alloys were produced by pressing followed by either solid or liquid p h a s e sintering. The properties of t h e solid p h a s e sintered specimens d e p e n d e d mainly on the
MPR January 1991 51