Fatigue properties of sintered steels

Fatigue properties of sintered steels

H at 1120°C a n d 1280°C. M i c r o s t r u c t u r m evolution w a s investigated. It w a s s h o w n t h a t h o m o g e n i s a d o n takes place b...

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H at 1120°C a n d 1280°C. M i c r o s t r u c t u r m evolution w a s investigated. It w a s s h o w n t h a t h o m o g e n i s a d o n takes place by r e d i s tribution of Mn through the vapour p h a s e followed by d i f f u s i o n o f N i a n d ~ In a l o n g a u s t e n i t c g r a i n b o u n d a r i e s a n d into bulk Fe particlcs. Cr diffuses m o r e slowly. D i m e n s i o n a l c h a n g e s were m o n i t o r e d by dilatometr~: Properties were e v a l u a t e d by h a r d n e s s m e a s u r e m e n t s .

Fatigue properties of sintered steels

S,Saritas et al (Gazi University, Ankara, Turkey.) T h e factors which d e t e r m i n e the structure of

sintcred

steels

were

outlined

Interaction of m a t e r i a l a n d process p a r a -

Porous materi a ,s

It w a s n o t e d t h a t p o r o u s m e t a l s arc u s e d as filters a n d t h a t m e a n s of a c c u r a t e l y

Not isostatic processing of open porosity PM composite material

m e a s u r i n g porosity, a n d it's d i s t r i b u t i o n ,

E,I.Figueredo. P.Beiss, (Inst, for Viaterials Science. Aachen, Germany.) It w a s n o t e d t h a t d a m a g e to blades m a y o c c u r i~ s t e a m t o ' h i n e s t h r o u g h erosion n n p a c t of water droplets. Blade life c a n be e x t e n d e d by removal o f droplets t h r o u g h vents in the t u r b i n e casmg. In order re m a k e f u r t h e r i m p r o v e m e n t in blade life it was p r o p o s e d re d r a w off water t h r o u g h pores in all s t a t i o n a r y surfaces. For this o p c n pore steel w a s developed based o n Cr alloy steel m a d e f r o m Fc and h i g h - C r steel p o w d e r s by h o t isostatic p r e s s i n g followed by electrochemical leaching o f the Fe.

m e m r s were reviewed in relation to structural features a n d a t t e n d a n t fatigue properties. Structural features were e x a m i n e d with

regard

m

aspects

of

fatigue

Guidelines for o p t l m i s a t i o n of material a n d process variables re fatigue life were established.

Porous powder materials for cleaning of fluids

LRPilinevich et aL (PM Research Inst.. Minsk. Belarus.) It w a s suggested d~at p o r u u s P M m a t e r i -

is required. Use of e d d y c u r r e n t techn i q u e s , in c o n j u u c n o n with m e t a l l o g r a phy, for s t u d y o f p o r o s i t y was described. D e v e l o p m e n t of a m e t h o d for n o n destructive d e t e r m i n a t i o n a n d c o n t r o l o f p o r o s i t y was r e p o r t e d .

Use of microhardness as a measure of uniformity of porous tungsten

J,V,Wood et al. (University of Nottingham, Nottingham, UK,) Application of

p o r o u s W as a high cur-

rent d e n s i t y c a t h o d e w a s d i s c u s s e d w i t h r e g a r d to p r o p e r t i e s , particularly porostty, it's c o n t r o l a n d t h e n e e d for u n i f o r m i t y S a m p l e s of p o r o u s W were m a d e by various methods, Microhardness measurem e n t s were u s e d to e v a l u a t e the u n i f o r m i ty of p o r o s i t y o f p o r o u s W s a m p l e s as a f u n c t i o n of p r o c e s s p a r a m e t e r s . T h e s t u d y w a s s u p p o r t e d by u s e of optical a n d electro n microscopy.

als could be u s e d as filters for cleani;lg

Production of sintered carbon steel from iron and cast iron powders

g a s e s a n d liquids. [t w a s s h o w n t h a t t h e r e

5 aperhard materia{s

is a lack of d a t a c o n c c r n m g t h c p r o p e r t i e s

l.Chicinas et aL (University of ClujNapoca, Cluj-Napoca, Romania.)

A new materials wRh increased damping capacity for superhard cutting tools

some

h w e s t i g a t i o n s into p r o d u c t i o n o f simered C-steel f r o m m t x t u r e s ot Fe a n d cast Fe p o w d e r s were described, h is s h o w n m a t the c o m p r e s s i b i l i t y o f t h e m i x t u r e s decreases w i t h increase in t h e cast Fe content, T i m e for h o m o g e m s a t i o n o f t h e mixtures was optimised. Sintering was in c n d o - g a s or v a c u u m . S a m p l e s with 0.4 o~ Jo C were sintered to ferrite/pcarlitc structure a n d 0 . 8 % C to a fine lametlar pearlite. H a r d n e s s a n d p i n - o n - d i s c wear tests were carried our.

Optimisation of sintering of iron-coppePgraphite powder mixtures

o f t h e s e a n d their suitability A s t u d y o f a r a n g e of p o r o u s metallic m a t e r i a l s , a n d polymeric

described

materials,

was

It w a s d e d u c e d t h a t the m o s t

effective m a t e r i a l consists of two layers, a m e t a l s u b s t r a t e , to provide s t r e n g t h a n d a n o u t e r layer of a p o l y m e r .

Application of PM for production of aluminium foams

E,Koza etal, (Warsaw University of Technology, Warsaw, Poland.)

A,D .Shevchenko. Onst, of Metal Physics, Kiev, Ukraine.) It was r e p o r t e d that a new" N i - T i alloy, w i t h high d a m p i n g capacity, h a d beer p r o d u c e d f o r m p o w d e r s , by u s e o f h i g h p r e s s u r e technology. T h e alloy was u s e d in v i b r a t i o n d a m p i n g e l e m e n t s o f c u t t i n g machinery using superhard proved to be effective, T h i s reduced tool wear.

tools and resulted in

It was r e p o r t e d t h a t At f o a m h a d been p r o d u c e d f r o m full y d e n s e e x t r u d e d At-Si alloy p o w d e r - f o a m i n g a g e n t m i x t u r e s by h e a t i n g above t h e m e l t i n g p o i n t o f A1.. F o a m s w i t h relative densities o f 0.1 to 0.5 were p r o d u c e d . Stereological

analysis of

t h e structural features was carried o u t

increase in service life of diamond tools through strong chemical bonding of cutting elements in matrix

Y.Naidich,. ~ nst. for Problems of Materials Science. Kiev, Ukraine.)

I.Ciupitu et al. (University of Craiova, Craiova, Romania.)

u s m g c o m p u t e r i m a g e analysis, m e c h a n i -

It was n o t e d t h a t t r a d i t i o n a l d i a m o n d tools t h e d i a m o n d grit is only m e c h a n i -

cal a n d electrical

p r o p e r t i e s wcre deter-

cally b o n d e d to t h e m a t r i x . It was r e p o r t -

An investigation to o p t i m i s e sintering, at

m i n e d . O p t i m u m p r o p e r t i e s were f o u n d

1050°C, 1100°C or 1150°C, o f F e - 5 % C u !, 1.6 or 2 } % g r a p h i t e p o w d e r m i x t u r e s was described. T h e rests were m accor-

at a relative d e n s i t y o f 0.2.

ed t h a t c h e m i c a l b o n d i n g h a d bccn develo p e d to give i n c r e a s e d b o n d s t r e n g t h

Determination of porosity by use of eddy currents

between d i a m o n d a n d m a t r i x . T h i s w a s a~tained by use o f e l e m e n t s with s t r o n g chemical a ffinity for C, i n c l u d i n g Ti, Cr.

LRPitinevich et at. (PM Research Inst,, Minsk, Belarus,)

matri× were p r o d u c e d

d a n c e w i t h a r e g r c s s m n analysis. It was s h o w n t h a t a n efficient s m t e r m g p r o c e s s could be d e d u c e d .

meta|-powderonet

V. D i a m o n d grit tools w i t h a W C - C o - C u a n d tested. Usc

AprR =oo3

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