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Technical notes
- 18
~Votes a n d C o m m e n l s .
[J. F. I.,
VANADIUM STEEL. Willans & R o b i n s o n are now p r o d u c i n g special v a n a d i u m steel alloys at the rate of 8oo t o n s per a u u u m at their Q u e e n s f e r r y works, E n g l a n d . T h e f e r r o - v a n a d i m n used for the m a n u f a c t u r e of t h e s e special alloys is o b t a i n e d fr~r.m the Llanelly w o r k s of the N e w V a n a d i u m Alloys C o m p a n y , in S o u t h Wales, a n d c o n t a i n s up to 3o per cent. of v a n a d i u m . T h e c h r o m e - v a n adium steels s h o w the m o s t r e m a r k a b l e properties. T h e s e contain f r o m IO to 2o per cent. v a u a d i u m . T h e v a n a d i u m steel i n d u s t r y is a l t o g e t h e r an E n g l i s h i n d u s t r y ; 8o per cent. of t h e p r o d u c t i o n is taken by the m o t o r car and m o t o r omni'bus m a n u f a c t u r e r s . In one case 15o axles of c h r o m e v a n a d i u m steel were o r d e r e d amt arc n o w r u n n i n g with satisfactory resuits, and a repeat order for 4o0 axles of the s a m e alloy has b e e n given. C h r o m e v a n a d i m n steel has also b e e n e x p o r t e d to France, a l t h o u g h an imp o r t duty of ~£5 per t o n has to be paid u p o n it. The effect of v a n a d i u m u p o n t e r n a r y and q u a t e r n a r y steels is to increase t h e resistance to b o t h static a n d d y n a m i c tests. T h e h i g h e s t t e s t yet o b t a i n e d from a c h r o m e - v a n a d i u m steel, after special heat t r e a t m e n t , was a m a x i m u m b r e a k i n g s t r a i n test of I93 t o n s p e r s q u a r e inch; this steel s h o w i n g at the s a m e time g r e a t r e s i s t a n c e to d y n a m i c and t o r s i o n a l tests. T h i s is a c o m b i n a t i o n of p r o p e r t i e s which has n e v e r been obtained before, and is t h e peculiar feature of the c h r o m e - v a n a d i u m steels, T h e nickelv a n a d i u m steels are of g r e a t s t r e n g t h , b u t s h o w m u c h lower resistance to d y n a m i c a n d torsional t e s t s . - - E n g , and Mining Jour. TECHNICAL NOTES. Care s h o u l d be o b s e r v e d in p l a c i n g d i r e c t - c u r r e n t m o t o r s where t h e r e is risk of g a s ; for the explosive m a y be ignited by s p a r k or heat. Not only does m o i s t u r e in coal cause it to c r u m b l e on e x p o s u r e to the air, but each per cent. of m o i s t u r e p r e s e n t m e a n s 2o lbs. less fuel for each t o n of coal. A coal that r u n s h i g h in m o i s t u r e , will usually break or c r u m ble on e x p o s u r e to air; this s l a c k i n g b e i n g due to a toss of m o i s t u r e f r o m the c o m p o s i t i o n of the coal. T h e safest cable to use for d i r e c t - c u r r e n t w o r k in the mines, is t h e c o n c e n t r i c cable with double g a l v a n i z e d iron wire a r m o r i n g , a n d for t h r e e - p h a s e machines, the t h r e e - c o r e cable with similar protection. E x perience a n d careful o b s e r v a t i o n h a v e s h o w n that the wear on a rope increases with the speed. It is t h e r e f o r e better, if m o r e work is to be done, to increase the load and run at the s a m e speed, than to c a r r y the s a m e load at a g r e a t e r speed. In the c o n v e y a n c e of c o m p r e s s e d air, it should be r e m e m b e r e d t h a t t h e efficiency is diminished practically as the d i a m e t e r of the pipes is decrca,ed, which mean~, of course, t h a t the pipes should be as large as c o n veniently practicable, with c o m m o d i o u s receivers a d j o i n i n g the air c o m pressors. T h e fixed carbon of a coal will n o t e v a p o r a t e as m u c h water as a n equal w e i g h t of volatile c o m b u s t i b l e m a t t e r w h e n properly fired; h o w ever, in practice, so m u c h of the latter is lost that in d e t e r m i u i n g t h e s t e a m value of a coal, we m a y a s s u m e the c a r b o n to be the only useful c o n s t i t u e n t . ~ E n g , a*,d Min. Jour.
~Votes a n d C o m m e n l s .
[J. F. I.,
VANADIUM STEEL. Willans & R o b i n s o n are now p r o d u c i n g special v a n a d i u m steel alloys at the rate of 8oo t o n s per a u u u m at their Q u e e n s f e r r y works, E n g l a n d . T h e f e r r o - v a n a d i m n used for the m a n u f a c t u r e of t h e s e special alloys is o b t a i n e d fr~r.m the Llanelly w o r k s of the N e w V a n a d i u m Alloys C o m p a n y , in S o u t h Wales, a n d c o n t a i n s up to 3o per cent. of v a n a d i u m . T h e c h r o m e - v a n adium steels s h o w the m o s t r e m a r k a b l e properties. T h e s e contain f r o m IO to 2o per cent. v a u a d i u m . T h e v a n a d i u m steel i n d u s t r y is a l t o g e t h e r an E n g l i s h i n d u s t r y ; 8o per cent. of t h e p r o d u c t i o n is taken by the m o t o r car and m o t o r omni'bus m a n u f a c t u r e r s . In one case 15o axles of c h r o m e v a n a d i u m steel were o r d e r e d amt arc n o w r u n n i n g with satisfactory resuits, and a repeat order for 4o0 axles of the s a m e alloy has b e e n given. C h r o m e v a n a d i m n steel has also b e e n e x p o r t e d to France, a l t h o u g h an imp o r t duty of ~£5 per t o n has to be paid u p o n it. The effect of v a n a d i u m u p o n t e r n a r y and q u a t e r n a r y steels is to increase t h e resistance to b o t h static a n d d y n a m i c tests. T h e h i g h e s t t e s t yet o b t a i n e d from a c h r o m e - v a n a d i u m steel, after special heat t r e a t m e n t , was a m a x i m u m b r e a k i n g s t r a i n test of I93 t o n s p e r s q u a r e inch; this steel s h o w i n g at the s a m e time g r e a t r e s i s t a n c e to d y n a m i c and t o r s i o n a l tests. T h i s is a c o m b i n a t i o n of p r o p e r t i e s which has n e v e r been obtained before, and is t h e peculiar feature of the c h r o m e - v a n a d i u m steels, T h e nickelv a n a d i u m steels are of g r e a t s t r e n g t h , b u t s h o w m u c h lower resistance to d y n a m i c a n d torsional t e s t s . - - E n g , and Mining Jour. TECHNICAL NOTES. Care s h o u l d be o b s e r v e d in p l a c i n g d i r e c t - c u r r e n t m o t o r s where t h e r e is risk of g a s ; for the explosive m a y be ignited by s p a r k or heat. Not only does m o i s t u r e in coal cause it to c r u m b l e on e x p o s u r e to the air, but each per cent. of m o i s t u r e p r e s e n t m e a n s 2o lbs. less fuel for each t o n of coal. A coal that r u n s h i g h in m o i s t u r e , will usually break or c r u m ble on e x p o s u r e to air; this s l a c k i n g b e i n g due to a toss of m o i s t u r e f r o m the c o m p o s i t i o n of the coal. T h e safest cable to use for d i r e c t - c u r r e n t w o r k in the mines, is t h e c o n c e n t r i c cable with double g a l v a n i z e d iron wire a r m o r i n g , a n d for t h r e e - p h a s e machines, the t h r e e - c o r e cable with similar protection. E x perience a n d careful o b s e r v a t i o n h a v e s h o w n that the wear on a rope increases with the speed. It is t h e r e f o r e better, if m o r e work is to be done, to increase the load and run at the s a m e speed, than to c a r r y the s a m e load at a g r e a t e r speed. In the c o n v e y a n c e of c o m p r e s s e d air, it should be r e m e m b e r e d t h a t t h e efficiency is diminished practically as the d i a m e t e r of the pipes is decrca,ed, which mean~, of course, t h a t the pipes should be as large as c o n veniently practicable, with c o m m o d i o u s receivers a d j o i n i n g the air c o m pressors. T h e fixed carbon of a coal will n o t e v a p o r a t e as m u c h water as a n equal w e i g h t of volatile c o m b u s t i b l e m a t t e r w h e n properly fired; h o w ever, in practice, so m u c h of the latter is lost that in d e t e r m i u i n g t h e s t e a m value of a coal, we m a y a s s u m e the c a r b o n to be the only useful c o n s t i t u e n t . ~ E n g , a*,d Min. Jour.