Another wootz question

kisak · 16th December 2008, 10:22 AM

I suspect that it is at least largely dependant upon the ingot. Looking through Manouchehr's book he mentions that the finer pattern of Indian wootz would be due to quick cooling, resulting in a finer grain structure (which makes metallurgical sense). So that's one form of pattern which is ingot-dependant.

There would seem to be a limit to the amount of deformation you'd want to subject the steel to as well. Working it will tend to reduce the distances involved in the chemical segregation which forms the basis of the pattern, greatly reducing the time the steel can be kept hot before aid segregation starts to fade and disappear.

Also, taking the chance to add a question of my own. If we first look at http://www.tms.org/pubs/journals/JOM...even-9809.html it mentions that depending on how the steel was heat treated, we'd generally get bands of carbides in a pearlite matrix. In Manouchehr's book there's also mention of low-carbon variants (hypoeuctectoid) where the pattern is formed by ferrite banding instead.

This then raises the question of just how these blades would have been heat treated. To the best of my knowledge, any ferrite remaining in such low-carbon steel after the normal heat-quench-temper treatment would indicate that the heating stage wasn't properly done (too short soak time), whereas pearler turning up in the more high carbon steels would either indicate a rushed heating there as well, or an insufficient quenching leaving retained austenite (which can then decay into pearlite). In either case, as both ferrite and pearlite are considerably softer than martensite the hardened form of steel basically) and the carbides, I've been thought that the presence of either is to be considered a failure in most cases.

So all said and done I'm rather curious as to what forms of heat treatment may have been applied to crucible steel blades, why, and with what result.

16th December 2008, 10:22 AM	#2
kisak Member Join Date: Jul 2008 Location: Stockholm Posts: 182	I suspect that it is at least largely dependant upon the ingot. Looking through Manouchehr's book he mentions that the finer pattern of Indian wootz would be due to quick cooling, resulting in a finer grain structure (which makes metallurgical sense). So that's one form of pattern which is ingot-dependant. There would seem to be a limit to the amount of deformation you'd want to subject the steel to as well. Working it will tend to reduce the distances involved in the chemical segregation which forms the basis of the pattern, greatly reducing the time the steel can be kept hot before aid segregation starts to fade and disappear. Also, taking the chance to add a question of my own. If we first look at http://www.tms.org/pubs/journals/JOM...even-9809.html it mentions that depending on how the steel was heat treated, we'd generally get bands of carbides in a pearlite matrix. In Manouchehr's book there's also mention of low-carbon variants (hypoeuctectoid) where the pattern is formed by ferrite banding instead. This then raises the question of just how these blades would have been heat treated. To the best of my knowledge, any ferrite remaining in such low-carbon steel after the normal heat-quench-temper treatment would indicate that the heating stage wasn't properly done (too short soak time), whereas pearler turning up in the more high carbon steels would either indicate a rushed heating there as well, or an insufficient quenching leaving retained austenite (which can then decay into pearlite). In either case, as both ferrite and pearlite are considerably softer than martensite the hardened form of steel basically) and the carbides, I've been thought that the presence of either is to be considered a failure in most cases. So all said and done I'm rather curious as to what forms of heat treatment may have been applied to crucible steel blades, why, and with what result.