The densities of high-purity iron-carbon alloys in the spheroidized condition
- PDF / 433,813 Bytes
- 4 Pages / 612 x 792 pts (letter) Page_size
- 112 Downloads / 161 Views
ME 6A, JANUARY 1975-55
about 40 y e a r s ago. In 1934, T a m m a n n and Bandel 4 r e viewed the r e s u l t s of five such a t t e m p t s known to t h e m . We found a sixth r e f e r e n c e 5 not l i s t e d in t h e i r r e v i e w . Of the i n v e s t i g a t i o n s noted, only the r e s u l t s of Ishigaki s and Scheil 6 (pFe3C ~ 7.66 g//cc) a r e in f a i r a g r e e m e n t with the m o r e r e c e n t l y d e t e r m i n e d X - r a y d e n s i t i e s of Fe3C 7-14 (7.680 g//cc • 0.004).* The r e a d e r is r e f e r r e d *TheformulaFe3Cis usedexclusivelyin this paperin referenceto cementite havingthe composition6.6895 pct C (25.0 at pct C). to the e a r l y p a p e r s for p r o b l e m s r e l a t e d to s a m p l e p u r i t y , lack of s p h e r o i d i z i n g a n n e a l s , l i n e a r e x t r a p o l a t i o n s a c c o r d i n g to p v s W r a t h e r than p-X v s W , etc. SPECIMEN PREPARATION A m o r e d e t a i l e d account of alloy p r e p a r a t i o n will be given l a t e r in conjunction with a p a p e r d e a l i n g with the d e n s i t i e s of the quenched s p e c i m e n s . Suffice it to say h e r e that the f i r s t t h i r t e e n a l l o y s l i s t e d in T a b l e I were p r e p a r e d by a r c - m e l t i n g 280 g r a m b a r s f r o m p r e weighed q u a n t i t i e s of p u r i f i e d iron* and s p e c t r o s c o p i c *Themajorsubstitutionalimpuritiesin thisironin ppm(1 ppm = 0.0001 wt pct) wereas follows:55 Ni, 40 Si, 30 A1,20 Cu, 20 W, 12 Mo, 12 Mn, 10 Cr, 10 S and lOP. c a r b o n r o d s . A t r a c e of b o r o n was also added to s a t isfy c e r t a i n r e q u i r e m e n t s of the quenched d e n s i t y exp e r i m e n t . The b a r s had roughly c i r c u l a r c r o s s - s e c t i o n s with diam of about 15 ram. They w e r e s e a l e d in i n d i v i d u a l , e v a c u a t e d q u a r t z t u b e s , h o m o g e n i z e d , then hot swaged at the h o m o g e n i z i n g t e m p e r a t u r e to 11 m m diam r o d s . A single d e n s i t y s p e c i m e n , 7 m m in diam by 38 m m in length, was m a c h i n e d f r o m each alloy. The s u r f a c e s of t h e s e s p e c i m e n s w e r e polished through 600 grit e m e r y p a p e r then e l e c t r o - p o l i s h e d . The homoge n i z i n g t r e a t m e n t r e f e r r e d to above c o n s i s t e d of the following: (i) alloys c o n t a i n i n g l e s s than 1 pct C w e r e held at 1000~ for 72 h, (ii) those c o n t a i n i n g f r o m 1.1 to 1.9 pct C w e r e held at 1150~ for 72 h. The 4.17 pct C s p e c i m e n was cut f r o m a m u l t i p l y a r c - m e l t e d s l a b whose d i m e n s i o n s were a p p r o x i m a t e l y 3.8 • 2.5 • 0.6 cm 3. A s l a b was u s e d in o r d e r to app r o a c h chill c a s t i n g conditions, a n e e d which a r o s e b e c a u s e this alloy could not be h o m o g e n i z e d by heating into a s i n g l e phase field. The d e n s i t y s p e c i m e n cut from the s l a b was 1.5 • 1.5 • 0.3 cm 3. Its s u r f a c e s w e r e polished in a m a n n e r
Data Loading...
