Tuesday, January 19, 2016

PERITECTIC Rn_Tn

      a few months back we started to take trial castings of peritectic grade steels. more than generally expected breakouts, we had start of casting failures due to tundish inner-working lining temperature losses in large tundishes (~ 30T working capacity) with relatively smaller dia nozzle openings (~12mm overlapping round ports) and smaller billets (150mm * 150mm ).


      some 5 years back, while working in bloom (250 *250 & 320 *250) casters, we had to face the menace of breakouts that are an inherent threats in casters where the mould levels were controlled manually.

      the approach for breakouts analysis was sooooo unsystematic, we became fed up with the entire workculture. esp, when breakdowns are blamed on us, we wanted to have a better understanding of casting PERITECTIC grade steel. that naturally led to the very basic of physical metallurgy, iron-iron carbide equilibrium phase diagram, more focussed on the top-left of it. that is the peritectic region was given full attention. and to understand that portion better, i drew up this pic in ms-paint.

       to my understanding, peritectic reactions involve 2 different reactants( solid-A + liquid ::::: delta ferrite +liquid steel) giving a product (solid-B ::::: austenite). and `transform'ation involves the conversion of delta-ferrite into austenite without reacting with liquid steel. tried my best to make the image self-explanatory.... here it is....



that was a time, when i had almost no knowledge of computers and image formats. i saved this pic in lossy " .JPG " format rather than lossless " .gif / .png " formats; lead to a compromise in quality. and thanks to my friend-bap=B.ArunPrasad for gifting me the first PC.      

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