Solidification of M2 high speed steel
- PDF / 2,827,447 Bytes
- 8 Pages / 612 x 792 pts (letter) Page_size
- 94 Downloads / 168 Views
The m e t a l l u r g y of t u n g s t e n - m o l y b d e n u m high speed s t e e l s is v e r y s i m i l a r to that of the t u n g s t e n types due to the s i m i l a r i t y of the t e r n a r y s y s t e m s F e - W - C and Fe-Mo-C. Nevertheless there are significant differe n c e s between T1 s t e e l and the n e w e r M2 grade designed as a s u b s t i t u t e for it. T h e r m a l a n a l y s i s i n d i c a t e s lower r e a c t i o n t e m p e r a t u r e s in M2, 9 and the c h a r a c t e r i s t i c morphology of the c a r b i d e n e t w o r k f o r m e d by e u t e c t i c s o l i d i f i c a t i o n of the i n t e r d e n d r i t i c liquid is d i s t i n c t l y different. ~'~7 Hence the p u r p o s e of the following work was to exa m i n e in d e t a i l the f r e e z i n g p r o c e s s and a s - c a s t m i c r o s t r u c t u r e of M2 high speed steel. M e t a l l o g r a p h i c and t h e r m a l a n a l y s i s e x p e r i m e n t s were d e s i g n e d to c o r r e l a t e m a j o r m i c r o s t r u c t u r a l f e a t u r e s with the s o l i d i f i c a t i o n r e a c t i o n s which p r o d u c e d them. Also c a r b o n and v a n a d i u m r e s p e c t i v e l y were added to the M2 s t e e l to o b s e r v e the effect on cooling c u r v e s and m i c r o s t r u c t u r e of s y s t e m a t i c i n c r e a s e s i n t h e c o n c e n t r a t i o n of an a u s t e n i t e s t a b i l i z e r and a f e r r i t e s t a b i l i z e r . F u r t h e r m e t a l l o g r a p h y and q u a n t i t a t i v e m i c r o a n a l y s i s were then c a r r i e d out to d e t e r m i n e the solute content of the d e n d r i t e s and the c o m p o s i t i o n s of the eutectic c a r b i d e s in M2 and in the high c a r b o n and high v a n a d i u m alloys. I) EXPERIMENTAL
PROCEDURES
A) U n i d i r e c t i o n a l F r e e z i n g and M e t a l l o g r a p h y of Solidification S t r u c t u r e s U n i d i r e c t i o n a l solidification was e m p l o y e d to p r o vide m e t a l l o g r a p h i c s e c t i o n s in which r e c o g n i z a b l e d e n d r i t i c growth f o r m s of known o r i e n t a t i o n facilitated interpretation of the m i c r o s t r u c t u r e . The s p e c i m e n s were p r e p a r e d by induction m e l t i n g ~ in. diam M2 b a r stock* in a modified c r y s t a l - g r o w i n g a p p a r a t u s and *Thebar stockwas suppliedby Universal-CyclopsSpecialtySteelDivision,CyclopsCorporation.The heat analysisof the materialwas 0.82 pet C, 6.11 pet W, 4.95 pet Mo, 4.18 pet Cr, 1 88 pet V, 0 009 pct S, 0.020 pct P, 0.26 pct Mn,0.31 pet Si, 0.20 pet Ni, 0.17 pet Co, 0.08 pet Cu, and 0.021 pct A1. withdrawing the c r u c i b l e v e r t i c a l l y downward at a VOLUME 3, APRIL 1972-919
'
.
I
I
I I 30
] I L
',:
. ~
~0
- -
"
i'-.L
. . . .
,.
~
.
=. .
1 ,
. .
I
~
'~.
:; . . . . . . . . . . . . . ,
I
,
I '
/
- ",
T'"
"
'"
I-:
....
....
:_
L.i
.....
:
.
.
'
~ .,'!
.
'
.
.
.
!
'
=' ' ; 1...,.I
' =' : ' "
:"
.
"
,.
Data Loading...
