Effect of manganese on annealing texture, plastic anisotropy, and mechanical properties of low-carbon steels containing
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THE
r e s u l t s of an e a r l i e r investigation1 indicated that the p l a s t i c a n i s o t r o p y p a r a m e t e r s r r n and At. and the strength of l o w - c a r b o n low-manganese (0.11 pct Mn) s t e e l s were m a r k e d l y improved by the additions of phosphorus. These b e n e f i c i a l effects w e r e o b s e r v e d in both v a c u u m - m e l t e d and a i r - m e l t e d s t e e l s , which were c o l d - r o l l e d 80 pct and subsequently annealed at t e m p e r a t u r e s in the range 710 to 820~ (1310 to 1508~ F o r the v a c u u m - m e l t e d s t e e l s , the i n c r e a s e in r m was a l m o s t l i n e a r with the concentratioh of phosphorus in the range 0.015 to 0.12 pct. F o r the a i r - m e l t e d s t e e l s , the i n c r e a s e in rrn with i n c r e a s i n g phosphorus a p p e a r e d to go through a maximum that o c c u r r e d at i n t e r m e d i a t e concentrations (~0.04 to 0.08 pct P). The o b s e r v e d a n i s o t r o p i c p r o p e r t i e s were consistent with the annealing textures developed in these s t e e l s . To explore the p o s s i b i l i t y for p r a c t i c a l a p p l i c a t i o n s of these phosphorus-containing s t e e l s , it is d e s i r a b l e to e s t a b l i s h the r a n g e s of manganese and carbon conc e n t r a t i o n s that yield excellent p r o p e r t i e s for deepdrawing applications. The p r e s e n t investigation was undertaken to d e t e r m i n e the effect of manganese content on the annealing texture, p l a s t i c anisotropy, and other mechanical p r o p e r t i e s of phosphorus-containing low-carbon steels. MATERIALS AND EXPERIMENTS Vacuum-Melted and A i r - M e l t e d Steels F o u r levels of manganese in the range 0.06 to 0.30 pct in v a c u u m - m e l t e d and a i r - m e l t e d s t e e l s having a base composition of 0.02 pct C, 0.02 pct Si, and 0.07 pct P, w e r e s e l e c t e d . A 200-pound (90.8 kg) split heat was melted in vacuum and was c a s t into four 50-tb HSUN HU is ResearchConsultant with U.S. Steel Research Laboratory, Monroeville,PA 15146. Manuscript submitted April 1, 1977. METALLURGICALTRANSACTIONSA
(22.7 kg) ingots, 3 by 5-1/2 by I0 inches (7.5 by 14 by 25 cm), each with a different amount of manganese. The a i r - m e l t e d s t e e l s were produced from four individual lO0-1b (45.5 kg) heats with the s a m e a i m compositions as the v a c u u m - m e l t e d s t e e l s , and were c a s t into ingots 3 by 8 by 14 inches (7.5 by 20 by 36 cm). To control the r i m m i n g action in solidification, s m a l l amounts of aluminum w e r e added to the a i r melted steels. Hot-Processing Procedures The h o t - p r o c e s s i n g p r o c e d u r e s employed were e s s e n t i a l l y the s a m e as those d e s c r i b e d in an e a r l i e r investigation. I F o r the v a c u u m - m e l t e d s t e e l s , the ingots were heated to 1230~ (2250~ and h o t - f o r g e d to a p p r o x i m a t e l y 2-3/4 by 4-1//2 inches (7 by 11 cm) in c r o s s section. The forged p i e c e s were the
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