In Situ Tensile Deformation of TRIP Steel / Mg-PSZ Composites

2013 ◽  
Vol 738-739 ◽  
pp. 77-81 ◽  
Author(s):  
Anja Weidner ◽  
Harry Berek ◽  
Christian Segel ◽  
Christos G. Aneziris ◽  
Horst Biermann
Keyword(s):  
Phase Transformation ◽  
Tensile Deformation ◽  
Electron Backscatter Diffraction ◽  
Deformation Energy ◽  
Martensitic Phase ◽  
Martensitic Phase Transformation ◽  
Steel Matrix ◽  
Austenitic Phase ◽  
Martensitic Phase Transformations

Composite material on the basis of a TRIP (transformation induced plasticity) steel with zirconia particles as reinforcement was produced by powder metallurgical technology and conventional sinter process. The goal of such type of material is to obtain exceptional mechanical properties like high deformation energy absorption due to the combination of martensitic phase transformations both in steel and ceramic. The steel matrix was made of the commercial steel AISI 304, which shows a deformation-induced martensitic phase transformation from the austenitic phase (fcc) into the α’-martensite (bcc). The zirconia particles were partially stabilized with MgO and show a stress-assisted martensitic phase transformation from the tetragonal to the monocline phase. Flat specimens were tensile deformed in-situ in a scanning electron microscope in order to follow the damage behaviour of the material. Some zirconia particles were characterized before and after tensile testing both by backscattered electron contrast as well as by electron backscatter diffraction (EBSD) in combination with energy dispersive X-ray spectroscopy (EDS).

In situ investigations of the fcc to hcp martensitic phase transformation in CoNi

1990 ◽  
Vol 48 (4) ◽  
pp. 546-547
Author(s):  
H.P. Karnthaler ◽  
T. Waitz
Keyword(s):  
Phase Transformation ◽  
High Temperature Phase ◽  
Martensitic Phase ◽  
Martensitic Phase Transformation ◽  
Stable Configuration ◽  
Temperature Phase ◽  
Spark Erosion ◽  
Fcc Phase ◽  
Low Temperature Phase

CoNi alloys show like pure Co a martensitic phase transformation between the fcc high temperature phase and the hcp low temperature phase. In Co+32%Ni the mean transformation temperature is at room temperature RT. Since the hysteresis is rather large (± 150°C) both phases can be observed in a stable configuration at RT. The two close packed lattices can transform into each other by the movement of a Shockley partial dislocation on every other close packed plane. In the case of the fcc → hcp transition there are four {111} planes which can act as habit planes. Therefore, caused by topological reasons the growing lamellas will hinder each other during their expansion. This seems to be an important difference to the reversed transformation where only one habit plane exists.Single crystals of Co+32%Ni were grown under vacuum by a modified Bridgeman technique. The crystals were in the fcc phase at RT. Discs of 1mm diameter with 〈112〉 orientation were prepared by spark erosion.

Effect of Stress State and Temperature on the Kinetics of Martensitic Phase Transformation in TRIP-Assisted Steel

2015 ◽  
Vol 651-653 ◽  
pp. 27-31 ◽  
Author(s):  
Hwi Geon Kim ◽  
Jin Woo Lee ◽  
Frederic Barlat ◽  
Dae Yong Kim ◽  
Myoung Gyu Lee
Keyword(s):  
Phase Transformation ◽  
Stress State ◽  
Simple Shear ◽  
Magnetic Measurements ◽  
Martensitic Phase ◽  
Martensitic Phase Transformation ◽  
Plane Strain Tension ◽  
Martensite Content ◽  
Stress States

The effects of the stress state and temperature on the martensitic phase transformation behavior in TRIP 780 steel were investigated using multi-axial experimental techniques. Various mechanical experiments are performed to differentiate the stress state and temperature effects. For this purpose, five different stress states were considered; i.e., uniaxial tension, uniaxial compression, equibiaxial tension, plane strain tension and simple shear. A temperatures both 25 and 60 °C for each stress state condition except the simple shear test were investigated. In-situ magnetic measurements were performed to mesure the evolution of the martensite content throughout each experiment. Finally, a new martensitic transformation kinetics model for the TRIP 780 steel is proposed to take the effect of stress state and temperature into account.

Sign in / Sign up

Export Citation Format

Share Document