Wear behaviour of nitrided steel

Wear behaviour of nitrided steel

P o w d e r production PRODUCTION OF GAS ATOMIZED BRONZE POWDER B. Xinguo (Beijing Non-Ferrous Powder Factory, Beijing, China), PM Technology, Vol 11...

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P o w d e r production PRODUCTION OF GAS ATOMIZED BRONZE POWDER

B. Xinguo (Beijing Non-Ferrous Powder Factory, Beijing, China), PM Technology, Vol 11, No 4, 1993, 189-192. (In Chinese). The p r o d u c t i o n of gas atomized bronze powder, on a n e w p r o d u c t i o n line, is described. The technological features are discussed. The properties of 6 / 6 / 3 bronze p o w d e r p r o d u c e d by t h e old a n d new processes are compared. Production p r o b l e m s are analysed.

Fundamentals DETERMINATION OF SPECIFIC SURFACE OF POWDERS BY GAS ADSORPTION M E T H O D S

L. Zhongquan, L. Yulian (Central Iron a n d Steel research Inst., Beijing, China), PM Technology, Vol 11, No 4, 1993, 289-294. (In Chinese). M e t h o d s for t h e d e t e r m i n a t i o n of specific surface of powders by m e a n s of gas a d s o r p t i o n are described. Static a n d dynamic techniques a n d N a n d i n e r t gases are used. Using Kr a m i n i m u m specific surface of 0.001 m2/gm was measured.

Products: Aluminium STRUCTURES AND PROPERTIES OF RAPIDLY SOLIDIFIED ALUMINIUMSILICON-COPPER-MAGNESIUM ALLOY

C. Guiyun et al (Academia Sincia, Shenyang, C h i n a ) , PM Technology, Vol l l , No 1, 1993, 3-7. (In Chinese). The p r o d u c t i o n of RS Al-18.6wt%Si4.3%Cu-0.66%Mg powder is described. The relationship between structure and properties is established. Tensile s t r e n g t h s at room t e m p e r a t u r e up to 430 MPa after h e a t t r e a t m e n t are r e p o r t e d a n d a t 200°C t h e s t r e n g t h is 370 MPa. G o o d w e a r resistance is also reported.

Iron and steel PROPERTIES AND MICROSTRUCTURE OF SINTERED MOLYBDENUM S T E E L S

J.M. Riuz-Prieto et al (Polytechnic University of Madrid, Madrid, Spain), Powder Metallurgy, Vol 37, No 1, 1994, 53-56. T h e e f f e c t s of %C, p o w d e r t y p e , prealloyed or e l e m e n t a l m i x t u r e s , a n d

38 MPR October 1994

heat treatment on the physical and mechanical properties of sintered 1.5wt% Mo steels were investigated using process conditions similar to those used industrially. S I N T E R E D DUPLEX AUSTENITICFERRITIC STAINLESS S T E E L S FROM PREALLOYED AND MIXED POWDERS

J.M. Ruiz-Prieto et al (Polytechnic University of Madrid, Madrid, Spain), Powder Metallurgy, Vol 37, No l, 1994, 57-60 I n v e s t i g a t i o n s of s i n t e r e d d u p l e x austenitic-ferritic stainless steels are described. Prealloyed and elemental powder mixtures were used and structures, mechanical properties and dimensional stability during processing were studied. The results for prealloyed a n d m i x e d powders were similar for given sintering conditions and the same austenite:ferrite ratio. S t r e n g t h is reported to increase with increase in t h e p r o p o r t i o n of ferrite. D i m e n s i o n a l s t a b i l i t y d u r i n g s i n t e r i n g was b e t t e r for t h e prealloyed p o w d e r s . Low s i n t e r i n g t e m p e r a t u r e s r e s u l t e d in a lack of h o m o g e n e i t y a n d poor properties. EQUILIBRIA AND KINETICS OF GASMETAL REACTIONS DURING SINTERING OF STAINLESS S T E E L

R.M. Larsen, I~A. Thorsen (Technical University of Denmark, Lyngby, D e n m a r k ) , Powder Metallurgy, Vol 37, No 1, 61-66. A study, in w h i c h t h e removal of C a n d O from 316L stainless steel was m o n i t o r e d by m a s s s p e c t r o s c o p y of f u r n a c e gases, is described. Thermodynamic calculations were applied to the m e a s u r e m e n t s . The removal of O is r e p o r t e d to be aided by increased %C a n d h i g h s i n t e r i n g t e m p e r a t u r e . The lowest %C was o b t a i n e d by v a c u u m sintering. CORROSION RESISTANCE OF SINTERING STAINLESS S T E E L CONTAINING NICKEL BASED ADDITIVES

A. S h a r o n et al (University of t h e Negev, Beer Sheva, Israel), Powder Metallurgy, Vol 37, No 1, 1994, 67-71. The c o r r o s i o n b e h a v i o u r of s i n t e r e d austenitic stainless steel, containing a d d i t i o n s of Ni base brazing powder, was investigated in 0.5 M sulphuric acid. It is reported t h a t t h e corrosion resistance is increased for a d d i t i o n s in t h e range 1 to 5wt%. This is a t t r i b u t e d to reduction in porosity due to a t r a n s i e n t liquid p h a s e during sintering.

WEAR BEHAVIOUR OF N I T R I D E D STEEL

B. Ralph et al (Brunel University, Uxbridge, UK), Materials World, Vol 2, No 7, 1994, 365-368. Wear m e c h a n i s m s in steels are discussed with regard to nitriding a n d o t h e r surface h a r d e n i n g t r e a t m e n t s . It is s h o w n t h a t nitriding reduces wear r a t e s by two orders of magnitude. S h a r p t r a n s i t i o n s in wear, mild to severe to extremely severe, are n o t e d in u n t r e a t e d steels. In nitrided steels only mild a n d severe wear are observed. Wear m e c h a n i s m m a p s are c o n s t r u c t e d a n d t h e s e are r e p o r t e d to assist in m a t e r i a l s selection a n d to allow c o m p a r i s o n between surface t r e a t m e n t processes.

Titanium FORMING OF S I N T E R E D TITANIUM ALLOY BY HOT ISOSTATIC P R E S S I N G

L. Tae et al (North Western Inst. for NonFerrous Metals Research, Baoji, China), PM Technology, Vol 11, No 3, 1993, 184-188. The consolidation of Ti-14%A1-2%Nb by H I P is d i s c u s s e d w i t h r e f e r e n c e t o properties. The s t r u c t u r e is shown to be c(2/~ a n d t h e c o n c e n t r a t i o n of ~2 decreases with increase in HIP t e m p e r a t u r e . O p t i m u m h a r d n e s s a n d s t r e n g t h are r e p o r t e d to be given by HIP at ll00°C.

Tungsten CHEMICALLY ACTIVATED LIQUID PHASE SINTERING OF T U N G S T E N COPPER

J.L. J o h n s o n , R.M. G e r m a n (Pennsylvania State University, Pennsylvania, USA), Int J PowderMetaUurgy, Vol 30, No l, 1994, 91102. It is r e p o r t e d t h a t u p to lwt% Co h a d been a d d e d to W-Cu as a sintering e n h a n c e r a n d t h e r e b y improved properties. Sintering is i n h i b i t e d by t h e immiscibility of W a n d Cu. Effects of p o w d e r characteristics, alloy composition a n d process variables were investigated. Density, strength and microhardness were measured and correlated with microstructures, fracture surfaces and grain sizes. Optimum composition for W-10wt%Cu is 0.35%Co, sintered a t 1300°C for 1 h o u r in H giving a d e n s i t y of 16.8 g m / c m 3, a Vicker's h a r d n e s s of 3 0 4 t r a n s v e r s e r u p t u r e s t r e n g t h of 1110 MPa.