Temper embrittlement response and toughness of a rare earth treated Ni-Cr-Mo steel
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with r a r e e a r t h s in the ingot molds, was made a v a i l able f o r rials investigation by c o u r t e s y of the Naval Ship R e s e a r c h and Development L a b o r a t o r y . 12 Since the m a t e r i a l was not intended for elevated t e m p e r a ture s e r v i c e , its t e m p e r e m b r i t t l e m e n t c h a r a c t e r i s t i c s had not been e s t a b l i s h e d . 1~ T e s t coupons were r e c e i v e d from three 2-in. thick p l a t e s which had been roUed f r o m ingots t r e a t e d with i n c r e a s i n g amounts of m i s c h m e t a l , 50 pct of which was c e r i u m . The f i r s t t e s t coupon, DUZ, was f r o m the control plate and contained no r a r e e a r t h s . The second and third coupons, DVA and DVB, w e r e f r o m p l a t e s made f r o m ingots t r e a t e d with 1 lb/ton and 1 l b / t o n of r a r e e a r t h m e t a l s , r e s p e c t i v e l y . The base c h e m i s t r y of this heat according to the m a n u f a c t u r e r ' s ladle a n a l y s i s was: 0.17 pct C, 0.37 pct Mn, 0.014 pct P , 0.015 pct S, 0.22 pct Si, 2.75 pct Ni, 1.62 pct C r , and 0.34 pct Me. EXPERIMENTAL PROCEDURE The t e s t coupons were sectioned horizontally into three slabs about k - i n . thick. The two outer slabs 15 14 1:5 12
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In the e a r l y 1960's s e v e r a l f u l l - s i z e production heats of a N i - C r - M o s t e e l b e t t e r known as HY-80 s t e e l w e r e t r e a t e d with r a r e e a r t h s 9'~~ in an attempt to i m prove weldabitityxl and mechanical p r o p e r t i e s . F o r tunately, m a t e r i a l from an o p e n - h e a r t h heat, t r e a t e d
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I. R. SPRUNGand K. R. OLEN are Research Metallurgistand Group SupervisorProcessesMetallurgy,respectively,The Babcock and WilcoxCompany, Researchand DevelopmentDivision,Alliance,Ohio 44601. Manuscript submitted December 17, 1971. METALLURGICALTRANSACTIONS
0 -200
I
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-150
-I00 TEST
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-50 0 50 TEMPERATURE, F
I I00
150
Fig. 1--Impact properties of Cr-Ni steel with varying lanthanum concentrations. 2 VOLUME 3, NOVEMBER 1972-2939
f r o m each coupon w e r e heat t r e a t e d for 1 h at 1700~ w a t e r quenched, then t e m p e r e d 3 h at 1200~ and w a t e r quenched. M e t a l l o g r a p h i c e x a m i n a t i o n for p r i o r
Hate
Added
DUZ DVA DVB
0 1 lb/ton 1 ~ lb/ton
Element, Wt Pet Sb
Sn
P
As
S
Ce
The r e s u l t s of c h e m i c a l a n a l y s e s for the t r a c e e m b r i t t l i n g e l e m e n t s , s u l f u r , and c e r i u m * a r e given in *It was assumedthat recoverieswouldbe similarfor all the rare earth elements, therefore onlyanalysisfor total ceriumwas carriedout.
Table I. Concentration of the Embrittling Elements, Sulfur, and Cerium in the Test Plates
Mischmetal
RESULTS
Ce/S
0.001 0.005 0.016 0.003 0.019 0 0 0.001 0.004 0.017 0.003 0.015 0.013 0.87 0.001 0.005 0.017 0.004 0.009 0.01
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