The huffman-louat theory and the temperature dependence of yielding in iron and iron binary alloys
- PDF / 234,761 Bytes
- 2 Pages / 594 x 846 pts Page_size
- 115 Downloads / 206 Views
The Huffman-Louat Theory and the Temperature Dependence of Yielding in Iron and Iron Binary Alloys W. C. L E S L I E AND F. C. SCHWERER H U F F M A N and Louat ~-3 have r e c e n t l y studied the d e f o r m a t i o n of m e t a l s with the a s s u m p t i o n that the p r i n c i p a l mode of e n e r g y d i s s i p a t i o n is through d i s l o cation i n t e r a c t i o n with the conduction e l e c t r o n s . T h e y c o n c l u d e d that the a p p l i e d s t r e s s r e q u i r e d f o r s t e a d y motion of a d i s l o c a t i o n in a b c c m e t a l i s p r o p o r t i o n a l to the d i s l o c a t i o n v e l o c i t y divided by the e l e c t r i c a l r e s i s t i v i t y . As they i n d i c a t e d , it follows that a plot of the i n v e r s e of the y i e l d s t r e s s v s the i d e a l r e s i s t i v i t y should be a s t r a i g h t line whose slope is p r o p o r t i o n a l to the r e c i p r o c a l of the d i s l o c a t i o n v e l o c i t y and whose i n t e r c e p t r e p r e s e n t s a r e s i d u a l r e s i s t a n c e c h a r a c t e r i s t i c of the d i s l o c a t i o n c o r e . Huffman and Louat find that the y i e l d s t r e s s - r e s i s t i v i t y data f o r s e v e r a l b c c m e t a l s obey this r e l a t i o n quite well b e l o w t e m p e r a t u r e s of about ~ of the Debye t e m p e r a t u r e . The Debye t e m p e r a t u r e of i r o n is 420~ In v i e w of the s i m p l i c i t y of the r e l a t i o n s h i p of y i e l d s t r e s s to r e s i s t i v i t y and the r e l a t i v e e a s e of r e s i s t i v i t y m e a s u r e m e n t s , it i s i m p o r t a n t to t e s t f u r t h e r the validity of this r e l a t i o n . In this l e t t e r we r e p o r t our t e s t s of the a p p l i c a t i o n of the H u f f m a n - L o u a t r e l a tion to the y i e l d s t r e s s of i r o n and s o m e i r o n - b a s e s o l i d s o l u t i o n s in the t e m p e r a t u r e range 77 ~ to 300~ In any a c c e p t a b l e t e s t of t h i s t h e o r y , the y i e l d s t r e n g t h and r e s i s t i v i t y m e a s u r e m e n t s m u s t be made on s p e c i m e n s of the s a m e c o m p o s i t i o n . A l s o , the s p e c i m e n s m u s t be at l e a s t r e a s o n a b l y f r e e f r o m c o m p l i c a t i o n s c a u s e d by the p r e s e n c e of i n t e r s t i t i a l solute a t o m s . A c c o r d i n g l y , r e s i s t i v i t y m e a s u r e m e n t s w e r e made on s p e c i m e n s f r o m a heat of an F e - 0 . 1 5 wt pct T i al l o y whose y i e l d s t r e n g t h s had b e e n d e t e r m i n e d p r e v i o u s l y a s a function of t e m p e r a t u r e . 4'5 They w e r e t e s t e d in the a n n e a l e d condition, with a g r a i n s i z e of ASTM 5- 6. The function of the t i t a n i u m in this a ll oy i s to g e t t e r C, N, O, and S. One e f f e c t of such g e t t e r i n g is a s h a r p r e d u c t i o n in y i e l d and flow s t r e s s e s at t e m p e r a t u r e s n e a r a m b i e n t b e c a u s e of e l i
Data Loading...
