Loading…

Flash Player 9 (or above) is needed to view presentations.
We have detected that you do not have it on your computer. To install it, go here.

Like this presentation? Why not share!

Raabe MS&T Maraging Steel 2010 Houston

on

  • 522 views

Segregation and partitioning phenomena at phase boundaries of complex steels are important for their microstructural, mechanical, and kinetic properties. We present nanoscopic atom probe tomography ...

Segregation and partitioning phenomena at phase boundaries of complex steels are important for their microstructural, mechanical, and kinetic properties. We present nanoscopic atom probe tomography results across martensite/austenite phase boundaries in a precipitation-hardened maraging TRIP steel after aging at 450°C for 48 hours (12.2 at.% Mn, 1.9 at.% Ni, 0.6 at.% Mo, 1.2 at.% Ti, 0.1 at.% Si, 0.3 at.% Al, 0.05 at.% C). The system reveals compositional changes at the phase boundaries: Mn and Ni are enriched ~2.1 and 1.2 times, respectively, relative to the average matrix content. In contrast, Ti is depleted ~6.9 times relative to the average content, Al ~6.6 times, Mo ~2.0 times, and Fe ~1.2 times. The strong accumulation of Mn at the interfaces is of particular interest as it strongly affects the transformation equilibrium and kinetics in steels. We observe up to 27 at. % Mn in a 20 nm thick layer at the martensite/austenite phase boundary. This can be explained by a large difference in diffusivity between martensite and austenite. The high diffusivity in martensite leads to a Mn-flux towards austenite. The low diffusivity in austenite does not allow accommodation of this flux within the matrix. Consequently, the phase boundary moves towards martensite with a Mn-composition given by the local equilibrium condition. This interpretation relies on diffusion calculations performed with the method DICTRA. A mixed-mode approach involving finite interface mobility was also applied to refine the agreement with the experiments. In order to achieve a good agreement the diffusivity in martensite had to be increased compared to ferrite. This can be attributed to a high defect density.

Statistics

Views

Total Views
522
Views on SlideShare
522
Embed Views
0

Actions

Likes
0
Downloads
10
Comments
1

0 Embeds 0

No embeds

Accessibility

Categories

Upload Details

Uploaded via as Microsoft PowerPoint

Usage Rights

© All Rights Reserved

Report content

Flagged as inappropriate Flag as inappropriate
Flag as inappropriate

Select your reason for flagging this presentation as inappropriate.

Cancel

11 of 1

  • Full Name Full Name Comment goes here.
    Are you sure you want to
    Your message goes here
    Processing…
Post Comment
Edit your comment

    Raabe  MS&T  Maraging  Steel 2010  Houston Raabe MS&T Maraging Steel 2010 Houston Presentation Transcript