Coalescence of carbides in martensite crystals

Conclusions

• 1. The coalescence of carbides is a martensite needle occurs at various rates: the rate of carbide growth along the periphery is much faster than inside the needles. The difference in the stability of the carbides is apparently the result of a redistribution of elements contained in the solid solution.

• 2. The carbides which precipitated inside the grain have enough time to dissolve during tempering. The carbides which precipitate along the grain periphery at first form platelets which then spheroidize and arrange themselves in the form of chains along the contour of the former martensite needles. This explains the apperance of sorbite with a martensitic orientation during the tempering of alloy steels.