No abstract

A study has been carried out on an Fe--Q.11 % G-1.58% Si-Q.4% Mn-dual phase steel. The dual-phase microstructures and properties are significantly affected by both the intercritical temperature and cooling rate from (ex + y) field. Upon rapid cooling (water or oil quench) from the temperature range 735-820°C, the structure comprises ferrite + martensite. On the other hand, slow cooling (air cooling) from the temperature range 735-820°C produces microstructures containing ferrite + martensite + pearlite/bainite and more favourable mechanical properties as: 0"0.2 = 281-296 MPa, O"UTS = 632-690 MPa, TE = 26-30% and continuous yielding behaviour. MikrogefUge und Eigenschaften eines e-Mn-Si-Dualphasenstahls. Es wurde ein Fe--Q, 11%-G-1 ,58%-Si-Q,4%-Mn-Dualphasenstahl untersucht. Das Dualphasen-MikrogefUge und die Eigenschaften werden durch die interkritische Temperatur und die Abkuhlqeschwindiqkeit aus dem ex-y-Gebiet beeinfluBt. Bei schneller Abkuhlung (mit Wasser oder 01) von 735 bis 820°C besteht das GefUge aus Ferrit und Martensit. Andererseits besteht das GefUge nach langsamer Abkuhlung von 735 bis 820°C aus Ferrit, Martensit und PerlitiBainit mit sehr guten Eigenschaften wie R O • 2 = 281-296 MPa, R m = 632-690 MPa, A = 26-30 % und einer kontinuierlichen Streckgrenze.

The objective of this investigation was to study the effect of the intercritical temperature and percentage of cold‐deformation on the kinetics auf austenite formation during the intercritical annealing in the alpha + gammy (α + γ) phase field of the iron‐carbon phase diagram. This investigation was carried out on an Fe–0.11 C–1.58Mn–0.4 Si ferritic‐pearlitic alloy with different structures of 0% (hot‐rolled), 25% and 50% cold‐deformation. The intercritical annealing temperatures were 735, 750°C and the intercritical annealing time ranged from 15 to 1815 s. It has been observed that recrystallization of the deformed ferrite was completed before any austenite formation. Surprisingly, it was noted that the recrystallized ferrite grain size was independent of percentage cold‐deformation. Furthermore, it was expected that cold‐deformation accelerates the kinetics of austenite formation. Nevertheless, the amounts of austenite formed from pearlite dissolution were mostly equal, irrespective of the starting condition. As has been previously reported, increasing the intercritical annealing temperature was found to increase the amount of austenite.