Can anyone have any idea about this type of defect observed in TMT made from semi killed steel? The steel chemistry is: - C:-0.23%, Mn:-1.2%, S+P < 0.075%, Si-0.05%. What is the reason of origin of this type of solid core in TMTs?
The SEM EDS analysis of the core material is 78% Fe, 18% Oxyegn and 2% Mn.
Figure attached for reference.
Dear Dr Kumar:
Some insight at about the origin of problem can be find in previous question of RG system:
https://www.researchgate.net/post/What_is_the_reason_for_Voids_in_steel_bar_after_forging
Further attention should be pay to answer provided by Dr Himmelblau, despite another.
Kind regards
Marcos Nobre
Have you studied the phase diagram, see http://www.msiport.com/. I am a layman in this field, but I would say this is a different phase due to the different temperature upon cooling.
With best regards,
Alexander Kos
stochiometric composition of solid core shows that it should be FeO-MnO oxide entrapped inside the cast product. As it is semi killed product, complete removal of dissolved oxygen is not possible and slightly rimming action would happen and as a result oxygen moves to the core of cast. ultimately it is stochimetricaly sufficient to form FeO-MnO oxide core.... Theoretical composition should be 78% Fe and 22%O for FeO.... The solid core composition is almost equal to that....As the solid core dosent shows any lustre, it also confirms that solid core is non-metallic stuffs.
Actual thermodynamic conditions are not getting a homogenous phase therefore the deviation. You should find the temperature, time, and heat treatment to make of your mixture a single phase material (to solubilize the carbon).
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