Effect of selected CARBIDE forming elements on the GRAPHITE precipitation in wear resistant CAST IRON

Transcription

1 Effect of selected CARBIDE forming elements on the GRAPHITE precipitation in wear resistant CAST IRON Armin Paar, Thomas Trickl, Leonel Elizondo, Michael Brandner, Coline Béal, Christof Sommitsch Name Erstellerdatum / XX.XX.201X Seite XX 1

2 OVERVIEW Background & Objective Experimental procedure Investigated material Design of Experiments (DoE) and trial castings Results Total graphite amount Graphite particle density Particle roundness factor Summary & conclusions Armin Paar / Page 2

3 BACKGROUND Wear resistant, graphitic cast irons for rolling mill applications contain Cr, Mo, (V, Nb) as carbide forming elements (cfe) Graphite precipitation is influenced by these elements Limited amount of publications deal with this task Armin Paar / Page 3

4 OBJECTIVE ICDP material has to become more wear resistant but still contain a certain graphite content Combine large amounts of carbide forming elements (cfe) Cr, Mo, V, Nb, W were selected Forming MC, M 2 C, M 6 C, M 7 C 3, (M 23 C 6 ), Evaluate the effects of the cfe on the graphite precipitation Regarding single effects and if possible combined (interaction) effects Armin Paar / Page 4

5 INVESTIGATED MATERIAL Chemical analysis Based on Ni-hard (G-X330NiCr4-2) + Si C Si Ni Mn Mass-% [%] [%] [%] [%] Base mat Contents of Cr, Mo, V, Nb, W in two conditions Mass-% Cr Mo V Nb W [%] [%] [%] [%] [%] Min (-) Max (+) Armin Paar / Page 5

6 INVESTIGATED MATERIAL Microsctructure Graphite ~ % carbide ~ % graphite MC carbides + Martensitic matrix Cementite Martensitic matrix Source: A. Paar, L. Elizondo, M. Brandner, T. Trickl, B. Sonderegger, C. Béal and C. Sommitsch, Application of Thermo-Calc TCFE7 to high-alloyed mottled cast iron, Proceedings of Thermec 2016, Graz (2016) Armin Paar / Page 6

7 EXPERIMENTAL PROCEDURE Design of experiments and trial castings Minitab 17 used for DoE: res. V, randomized Trial castings: Factor Cr Mo V Nb W Factor Cr Mo V Nb W Stat. Nr. Stat. Nr kg high frequency induction furnace Casting temperature 1350 ± 5 C Armin Paar / Page 7

8 EXPERIMENTAL PROCEDURE Analysis of graphite precipitates Quantitative Light-optical microscope Graphite content Area-% of graphite [%] Particle density Number of particles per mm² [1/mm²] Particle roundness Relation between the circumferences of the measured particle and a circle with the same area (1 = circle) Armin Paar / Page 8

9 RESULTS: OVERVIEW Strong influence of carbide forming elements was observed Different intensity of Cr, Mo, V, Nb and W was observed Graphite content % Particle density particles per mm² Particle roundness Armin Paar / Page 9

10 RESULTS: OVERVIEW Trial No. 9 (Nb +) Trial No. 16 (all +) Total graphite amount: 6.23 % Particle density: 64 p/mm² Roundness: 0.58 Total graphite amount: 1.30 % Particle density: 23 p/mm² Roundness: 0.75 Armin Paar / Page 10

11 RESULTS: TOTAL GRAPHITE AMOUNT Factor Cr Mo V Nb W Graphite Factor Cr Mo V Nb W Graphite Stat. Nr. [area-%] Stat. Nr. [area-%] Armin Paar / Page 11

12 RESULTS: TOTAL GRAPHITE AMOUNT Armin Paar / Page 12

13 RESULTS: PARTICLE DENSITY Factor Cr Mo V Nb W Density Factor Cr Mo V Nb W Density Stat. Nr. [1/mm²] Stat. Nr. [1/mm²] Armin Paar / Page 13

14 RESULTS: PARTICLE DENSITY Armin Paar / Page 14

15 RESULTS: PARTICLE ROUNDNESS Factor Cr Mo V Nb W Roundness Factor Cr Mo V Nb W Roundness Stat. Nr. value Stat. Nr. value Armin Paar / Page 15

16 RESULTS: PARTICLE ROUNDNESS Armin Paar / Page 16

17 SUMMARY & CONCLUSIONS Single effects All investigated cfe reduce graphite amount + particle density All elements increase the particle roundness Nb has the smallest effect on graphite (amount, p. density, roundness) V has the strongest effect Mo has a clear impact on graphite W has a low effect (little bit higher than Nb) Effect of Cr was also measurable even if the step width was 0.2 % Nb W Mo Cr(?) V Armin Paar / Page 17

18 SUMMARY & CONCLUSIONS Combined effects Combined effects are hard to interpret correctly Only the most obvious obsvervations are shown here: Graphite amount: Nb interacts with Cr V, Mo overrule effect of W Graphite particle density: V has a very strong effect Mo increases the effect of Cr Nb V Mo Roundness factor of the graphite precipitations: Mo, V, Nb and W overrule the effect of Cr Nb interacts with Cr Armin Paar / Page 18

19 FUTURE PROSPECTS Further trials Confirmation of the derived effects with single element trials stepwise increasing of Mo, W Confirm the combined effects with selected trials Nb (!) Increase the step-width of Cr Thermodynamic calculations Explain the effects of the investigated cfe with the help of thermodynamic calculations (e.g. Thermo-Calc, MatCalc, ) Armin Paar / Page 19

20 Thank you for your attention! Armin Paar Thomas Trickl Leonel Elizondo Michael Brandner Eisenwerk Sulzau-Werfen, R. & E. Weinberger AG Bundesstraße Tenneck Coline Béal Christof Sommitsch IWS, Graz University of Technology Kopernikusgasse 24/ Graz Armin Paar / Page 20