STUDIES ON CEMENTITE CRACKS OF HIGH CARBON STEEL (I)
1956 Volume 42 Issue 12 Pages 1111-1117
Details
1956 Volume 42 Issue 12 Pages 1111-1117
This investigation deals with the causes of cavities which are occasionally observed at the centre of the rolled high-carbon bearing steel.
Conclusions are as follows:
(1) When some pressed or hammered billets are cooled down, very fine cracks, the width of which are less than 1/10μ, are formed in Acm cementite. These "Acm cementite cracks" are considered to be caused by the super-saturated hydrogen contained in the billets (hydrogen content are above 3.0cc/100) at the temp of below 200°C.
(2) These "Acm cementite cracks" grow to cavities during rolling process.
(3) These "Acm cementite cracks" can be observed in the form of macro-hair-cracks by etching of HCl, but cannot be observed by etching of oxidizing solutions like HNO3 and ammonium persulphate.
(4) These "Acm cementite cracks" cannot be observed in the form of flakes on fractured surface as far as the billets are simply cooled down.
