Reverse Transformation from Ferrite/Pearlite to Austenite and Its Influence on Structure Inheritance in Spring Steel 60Si2MnA

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Abstract

Reverse transformation at 725–800°C × 0–35 s from a ferrite/pearlite to austenite was investigated in spring steel 60Si2MnA with various pearlite fineness obtained by isothermal transformation. Then, its influence on the structure inheritance in the spring steel during heat treatment process was discussed. The results indicated that various pearlite fineness influences clearly start temperature of the reverse transformation. Austenite preferentially nucleates at the ferrite/cementite interface within pearlite, the neighboring pearlite colony boundary and the proeutectoid ferrite/pearlite boundary during the reverse transformation process. And the angle between pearlite lamellae and austenite growth direction has an important influence on austenite growth rate. Besides, the ferrite/pearlitic structure has structure inheritance phenomenon, because various hot-rolled microstructure affect the austenite nucleation and growth during heat treatment process.

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