126 Prakt. Met. Sonderband 46 (2014)
High-Temperature furnace (HT-LSCM), the formation of AF can be observed in situ [5-11]. 3. RESUL
Using a laser as a light source, even luminous materials such as steel can be observed up
to 1700 °C [5]. Due to the inert furnace atmosphere, the accurate adjustment of 3.1 SETTIM
austenitizing temperature and the well controllable cooling conditions, the interactions
between steel composition, austenite grain size, cooling rate, non-metallic inclusions and The austen
the AF amount can be analysed in detail. The present work focuses on the Therefore t
characterization of AF microstructures in HSLA steels using a combination of conventional the formatic
metallographic methods and modern high temperature microscopy. Samples are heat for a syster
treated in the high-temperature furnace attached to a LSCM. The determination of the final A standard
microstructure is done by etching and optical microscopy. Special attention is paid to the within this |
analysis of austenite grain size, which is one of the major influencing parameters on the less time e
formation of AF. The advantages of HT-LSCM and the essential benefits of the grain size i
combination of conventional and modern metallographic methods shall be pointed out. determinati
thermal etc
inside the ¢
2. EXPERIMENTAL PROCEDURE of austenit
evaluation.
The present study focuses on the characterization of acicular ferrite structures in Ti-alloyed determinec
HSLA steels with 0.23 % C, 1.5 % Mn and 0.05-0.4 % Ti. All investigations are done with grains per
so-called dipping samples. Therefore a steel melt was produced in a vacuum induction
furnace, wherefrom samples were taken by dipping a submerged body into the melt on
which the steel solidified. The detailed procedure of the dipping tests was already
described in a previous work [12]. The dipping samples are heat treated in the HT-LSCM.
[5,13-14]. Afterwards the samples are examined concerning AF amount and austenite
grain size by etching and optical microscopy. Fig. 1 gives an overview about the
experimental setup for the systematic analysis of the AF formation done within the project.
The present work focuses on the metallographic analysis of this setup. Therm:
Di . TN ED sample
ipping etallo- HT-LSCM allo-
Test os graphy ' graphy J
In Fig. 3 th
It can be s
1500 +
41 mm
ora, submerged boty dipping samples observation of Le es X 1000
vacuum furnace into met, sample by etching + phase transitions by etching +
with defined solidifies and is optical during heat optical
inclusion cooled with microscopy and treatment of Microscopy
landscape varying rates SEM/EDS dipping samples
Steel composition
Cooling rate 5
Austenite grain size
Non-metallic inclusions x Fig. 3
Fig. 1: Experimental setup and considered parameters of AF formation
