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5. H. Harvig: Jernkont. Ann., 1971, vol. 155, pp. 157-66. 6 . M. Hillert andM. Jarh Met. Trans. A, 1975, vol. 6A, pp. 553-59. 7 . M. Hillert andM. Jarl: Acta Met., 1977, vo]. 25, pp. 1-9. 8 . M. Jarl: Calphad, 1977, vol. 1, pp. 91-95. 9 . S. Hertzman andM.Jarl: TRITA-MAC-0144, Royal Institute of Technology Report, Stockholm, Sweden, 1978. 10. H. Schenck, M. Frohbert, andW. Kranz: Arch. Eisenhuettenwesen, 1963, vol. 34, pp. 825-30. 11. L, Kaufman andH. Bernstein: Computer Calculation o fPhase Diagrams, Academic Press, New York, 1970.

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The Relationship Between Solidification and Microstructure in Austenitic and Austenitic-Ferritic Stainless Steel W e l d s

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e . o T s e.too 0 t2s e.tse X-N F i g . 2--The 7 / ~ p h a s e b o u n d a r i e s in the Mn-N s y s t e m a c c o r d i n g t o calculation (full lines) and v a r i o u s experimental data. t o the t w o p h a s e s a n d p u t GMn e q u a l a n d t h e n t o s o l v e f o r °G~Mn - ° G ~ n . T h e r e s u l t w a s 760 J / m o l . In o r d e r t o estimate the temperature dependence o f the d i f f e r e n c e i n G i b b s e n e r g y the t w o t w o - p h a s e s p e c i m e n s a t 8 2 0 ° C w e r e a s s u m e d t o r e p r e s e n t the p h a s e boundaries. T h e p h a s e e q u i l i b r i u m was c a l c u l a t e d a n d t h e d i f f e r e n c e in G i b b s e n e r g y was a d j u s t e d u n t i l t h e c a l c u l a t e d p h a s e b o u n d a r i e s a g r e e d w i t h the e x p e r i m e n t s . A t e m p e r a t u r e d e p e n d e n t v a l u e was t h u s obtained as °G~Mn - °G~Mn = 530 + 0 . 1 7 . T J / / m o l .

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T h i s made it p o s s i b l e t o c a l c u l a t e t h e p h a s e boundaries b e t w e e n ~ a n d ~ as f u n c t i o n s o f t e m p e r a t u r e , T h i s was d o n e by s t a n d a r d m e t h o s z' a n d the r e s u l t i s c o m p a r e d w i t h the e x p e r i m e n t a l p o i n t s a c c o r d i n g t o K u d i e l k a , w h i c h a r e s i t u a t e d c l o s e s t t o the p h a s e b o u n d a r i e s a n d Kudielka's X - r a y s p e c i m e n s . See Fig. 2 . T h e r e s u l t is encouraging. T h e c a l c u l a t e d p h a s e boundaries a g r e e w e l l w i t h m o s t o f the e x p e r i m e n t a l p o i n t s a n d t h e s m a l l d e v i a t i o n s do not s e e m t o be s e r i o u s . T h e a u t h o r is i n d e b t e d t o P r o f e s s o r M a t s Hillert f o r d i s c u s s i o n s o f t h i s m a n u s c r i p t . T h i s w o r k was f i n a n c i a l l y s u p p o r t e d