Abnormal ferrite in hyper-eutectoid steels
The microstructural characteristics of ultra-high carbon hyper-eutectoid Fe-C and Fe-C-Cu experimental steels have been examined after isothermal transformation in a range just beneath the eutectoid temperature. Particular attention was paid to the formation of so-called abnormal ferrite, which refers to coarse ferrite grains which can form, in hyper-eutectoid compositions, on the pro-eutectoid cementite before the pearlite reaction occurs. Thus it is confirmed that the abnormal ferrite is not a result of pearlite coarsening, but of austenite decomposition before the conditions for coupled growth of pearlite are established. The abnormal ferrite formed on both allotriomorphic and Widmanstaetten forms of pro-eutectoid cementite, and significantly, it was observed that the pro-eutectoid cementite continued to grow, despite being enclosed by the abnormal ferrite. Under certain conditions this could lead to the eventual formation of substantially reduced amounts of pearlite. Thus, a model for carbon redistribution that allows the proeutectoid cementite to thicken concurrently with the abnormal ferrite is presented. The orientation relationships between the abnormal ferrite and pro-eutectoid cementite were also determined and found to be close to those which have been reported between pearlitic ferrite and pearlitic cementite.
- Research Organization:
- Chiang Mai Univ. (TH)
- OSTI ID:
- 20034190
- Journal Information:
- Acta Materialia, Vol. 48, Issue 7; Other Information: PBD: 19 Apr 2000; ISSN 1359-6454
- Country of Publication:
- United States
- Language:
- English
Similar Records
Microscopic characterization of {epsilon}-Cu interphase precipitation in hypereutectoid Fe-C-Cu alloys
A microscopic examination of the precipitation phenomena occurring during the isothermal pearlitic transformation in high carbon-copper nickel steels