Corrosion resistance of austenitic stainless steels sintered in a commercial furnace

Corrosion resistance of austenitic stainless steels sintered in a commercial furnace

PM The p r o d u c t i o n of a B i ( P b ) S r C a C u O s u p e r c o n d u c t o r p o w d e r by m i c r o w a v e heating of a m i x t u r e of ...

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PM

The p r o d u c t i o n of a B i ( P b ) S r C a C u O s u p e r c o n d u c t o r p o w d e r by m i c r o w a v e heating of a m i x t u r e of m e t a l n i t r a t e s in presence of a catalyst was described. The powder was r e p o r t e d to have a plate-like morphology a n d to be 1 to 2 ~ m in size. Superconducting specimens w i t h a high critical c u r r e n t density were r e p o r t e d to have been produced. Details of t h e process were given. E L E C T R O N BEAM T E C H N I Q U E FOR FORMATION OF CARBIDE FILMS TO GIVE R O U G H N E S S O F METAL ROLLS

LITERATURE

REVIEW

WEAR A N D C O R R O S I O N R E S I S T A N C E OF ADVANCED HIGH VANADIUM PM TOOL S T E E L S K.E. P i n n o w et al ( C r u c i b l e Research, Pittsburg, USA). Work to develop high V a n d high Cr PM steels for b a r p r o d u c t s a n d HIP/composite applications was described. Wear and c o r r o s i o n p r o p e r t i e s were o u t l i n e d a n d c o m p a r e d with conventional a n d PM tool steels used in m e t a l forming, plastics a n d food processing industries.

Tool design L_A~ Barkov et al (State Technical University, Russia). A t e c h n i q u e for increasing t h e surface h a r d n e s s a n d r o u g h n e s s of high s t r e n g t h rolls was described. A Cr coating is applied by electrodeposition or by deposition from a n o x i d e / m e t a l powder mixture. The Cr is converted into carbide by s i m u l t a n e o u s s p u t t e r i n g of C o n t o t h e surface a n d electron beam bombardment. The application was said to be t h e cold rolling of p h o t o g r a p h i c film.

Corrosion C O R R O S I O N R E S I S T A N C E OF AUSTENITIC STAINLESS STEELS S I N T E R E D IN A COMMERCIAL FURNACE C. Lall et al (Midwest Sintered Products Corp, Riverdale, USA). A n u m b e r of austenitic stainless steels were c o m p a c t e d u n d e r various conditions, d e l u b r i c a t e d a n d s i n t e r e d in d i f f e r e n t a t m o s p h e r e s in o r d e r to d e t e r m i n e t h e effects of composition and process variables on corrosion resistance. The d a t a on corrosion in 5wt% salt solution were p r e s e n t e d a n d d i s c u s s e d in t e r m s of m i c r o s t r u c t u r e a n d N, O a n d C contents. CORROSION R E S I S T A N C E O F STAINLESS STEELS AND OTHER S T E E L S IN M E T H A N O I ~ B A S E D F U E L S C. Lall et al (Midwest Sintered Products Corp, Riverdale, USA). The corrosion of PM steels, in m e t h a n o l b a s e d automotive fuels, was discussed in t h e light of t h e aggressive a t t a c k by t h e s e fuels. The m o s t serious p r o b l e m s were said to occur with Cu bearing or Cu infiltrated s t e e l s a n d it w a s s u g g e s t e d t h a t t h e difficulty could be overcome by t h e use of PM s t a i n l e s s steels. The corrosion resistance of s a m p l e s of 304L, 316L, Fe0.8%C a n d Fe-0.8%C-2%Cu, in 'aggressive m e t h a n o l ' were compared. The plain steels were r u s t e d w i t h i n 24 h o u r s b u t t h e stainless steels were s h o w n to be very c o r r o s i o n r e s i s t a n t . Various fuels were identified for corrosion testing and suggestions were m a d e for f u r t h e r research.

46 MPR January 1993

TOOLING D E F L E C T I O N S IN COMPACTION J. Porter et al (Cincinnati Inc, Cincinnati, USA). Tool deformations, in a fully instrumented compaction press, were m e a s u r e d as a f u n c t i o n of c o m p a c t i o n loads, for Fe p o w d e r s . F i n i t e e l e m e n t m e t h o d s were used to c o n s t r u c t a model of t h e process a n d deflections a n d spring back were calculated. The ability of t h e model to simulate densification, resulting stresses a n d tool deflections was r e p o r t e d to provide t h e m e a n s to b a l a n c e deflection a n d spring back a n d to avoid c o m p a c t i o n defects. S T R E S S D I S T R I B U T I O N IN R I N G S D U R I N G COMPACTION AT THE START OF EJECTION L. A c k e r m a n n (Sintertech, France). S p r i n g b a c k in c o m p a c t e d p a r t s w a s discussed w i t h reference to t h e factors w h i c h c o n t r i b u t e , die d e f o r m a t i o n a n d elastic recovery of t h e part. The a m o u n t of s p r i n g b a c k was related to t h e interference between p a r t a n d die d u r i n g p a r t ejection. The interference was calculated using Lame's e q u a t i o n s . The objective of t h e s t u d y was to check t h e a s s u m p t i o n t h a t t h e p r e s s u r e in a ring s h a p e d p a r t was u n i f o r m in a h o r i z o n t a l layer. F u r t h e r investigations of this topic were outlined.

Wear resistant materials WEAR R E S I S T A N T S T E E L MATRIX METAL MATRIX C O M P O S I T E S ( M M C ) P R O D U C E D BY HIP V.O.G. Bryggman et al (Swedish Inst. of Production Engineering Research, Sweden). Steel m a t r i x MMCs w i t h SiC or A1203 particles were processed to full density by HIP. The m e c h a n i c a l p r o p e r t i e s a n d wear resistance data were determined and structures examined by electron microscopy. It was shown that the abrasive wear was 35 t i m e s greater t h a n

t h a t of AISI/SAE grade A2 steel a t h a r d n e s s 53Rc. Dry a n d lubricated adhesive wear was 7 a n d 28 t i m e s greater a t 59Rc, respectively. The coefficients of friction were r e p o r t e d to be similar to t h o s e for steel. E F F E C T S O F A D D I T I O N S O F ALLOYED IRON POWDERS ON P R O P E R T I E S O F PM TOOL S T E E L S L.E.G. C a m b r o n e r o et al (Polytechnical University of Madrid, Spain). The effects of diluting PM M2 a n d T15 high speed steels with alloyed Fe powders was investigated as a m e a n s of p r o d u c i n g w e a r r e s i s t a n t p a r t s at reduced cost. An a n a l y s i s of s t r u c t u r e a n d m e c h a n i c a l p r o p e r t i e s of t h e alloys was presented. WEAR R E S I S T A N T H I G H S P E E D S T E E L ( H S S ) METAL MATRIX C O M P O S I T E S (MMC) H. C a r v a l h i n o s e t al (LNETI, Lisbon, Portugal). A n i n v e s t i g a t i o n of t h e e f f e c t s of a d d i t i o n s of A l 2 0 p a r t i c l e s , p l a i n o r coated with TiN, on t h e s t r u c t u r e s a n d p r o p e r t i e s of M2/3 HSS, was reported. It was f o u n d t h a t t h e wear resistance was i n c r e a s e d by b o t h t y p e s of c e r a m i c particles. The u n c o a t e d particles r e s u l t e d in a reduction of t r a n s v e r s e r u p t u r e stress from 1600 to 1250 MPa a n d t h i s was a t t r i b u t e d to p o r o s i t y a t t h e p a r t i c l e / m a t r i x interface. In t h e case of t h e coated particles it was considered t h a t a reaction occurred at t h e interface w h i c h resulted in a s t r e n g t h c o m p a r a b l e with t h a t of t h e m a t r i x alloy. CONTROL OF P R O P E R T I E S A N D M I C R O S T R U C T U R E IN PM WEAR R E S I S T A N T ALLOYS G. Raisson et al (TECPHY, Imphy, France). It was r e p o r t e d t h a t t h e m e c h a n i c a l p r o p e r t i e s of PM Co b a s e alloys were s u p e r i o r to t h o s e of cast m a t e r i a l s due to m i c r o s t r u c t u r a l r e f i n e m e n t a n d t h e use of thermo-mechanical treatment. Increased s t r e n g t h was a c c o m p a n i e d by increased ductility a n d machinability. Applications for t h e alloys were discussed in relation to t h e properties. APPLICATION OF HIP TO MANUFACTURE O F PARTS WITH WEAR R E S I S T A N T COATINGS E.P. Kratt et al (NPO Vils, Russia). The a p p l i c a t i o n of w e a r r e s i s t a n t powder coatings, u p to 10 m m thick, consisting of 30 to 60% carbides in a m e t a l matrix, to p a r t s using HIP to consolidate t h e powder, was described. I n t e r a c t i o n s a t t h e coating/ s u b s t r a t e interface were studied a n d t h e results were presented. Applications of t h e w e a r r e s i s t a n t p a r t s were discussed.