Alloy design of nanoprecipitate-hardened high-Mn maraging-TRIP and -TWIP steels<br />D. Ponge, O. Dmitrieva, J. Millán, S....
Overview<br /><ul><li>Introduction
Compositions and processing
Mechanical properties and microstructures
Characterization of precipitations
Formation of new austenite during aging
Conclusions</li></li></ul><li>Introduction<br />Steel for automotive applications:<br />Good combination of strength, duct...
Small amountofaustenite (TRIP, TWIP)
Controlled precipitation hardening</li></li></ul><li>Overview<br /><ul><li>Introduction
Compositions and processing
Mechanical properties and microstructures
Characterization of precipitations
Formation of new austenite during aging
Conclusions</li></li></ul><li>Low carbon: ductile martensite<br />Compositions in mass%: classical maraging steel<br />Pre...
Low carbon: ductile martensite<br />Compositions in mass%: newlean maraging steels<br />PH<br />PH<br />PH<br />Precipitat...
Processing<br />Vacuuminductionmelting<br />Annealing<br />Hot deformation<br />Solution heat treatment<br />+ retained au...
Overview<br /><ul><li>Introduction
Compositions and processing
Mechanical properties and microstructures
Characterization of precipitations
Formation of new austenite during aging
Conclusions</li></li></ul><li>Hardness during aging at 450°C<br />12MnPH<br />09MnPH<br />15MnPH<br />12MnPH<br />g<br />0...
12MnPH after aging (48h 450°C)<br />precipitates in a`<br />no precipitates in<br />Dmitrieva et al. ActaMater 59 (2011)<b...
Tensile tests<br />Ni-Maraging<br />aged (450°C/48h)<br />(X3NiCoMoTi18-12-4)<br />quenched<br />12MnPH<br />aged (450°C/4...
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Alloy design of nanoprecipitate-hardened high-Mn maraging-TRIP and -TWIP steels

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High manganese steel conference trip maraging steels short version

  1. 1. Alloy design of nanoprecipitate-hardened high-Mn maraging-TRIP and -TWIP steels<br />D. Ponge, O. Dmitrieva, J. Millán, S. Sandlöbes, P. Choi, <br />A. Kostka,G. Inden, D. Raabe<br />Düsseldorf, Germany<br />WWW.MPIE.DE<br />d.raabe@mpie.de<br />Dierk Raabe<br />
  2. 2. Overview<br /><ul><li>Introduction
  3. 3. Compositions and processing
  4. 4. Mechanical properties and microstructures
  5. 5. Characterization of precipitations
  6. 6. Formation of new austenite during aging
  7. 7. Conclusions</li></li></ul><li>Introduction<br />Steel for automotive applications:<br />Good combination of strength, ductility, price<br />LeanMaragingTRIP Steels<br /><ul><li>Ductilelowcarbon martensite matrix
  8. 8. Small amountofaustenite (TRIP, TWIP)
  9. 9. Controlled precipitation hardening</li></li></ul><li>Overview<br /><ul><li>Introduction
  10. 10. Compositions and processing
  11. 11. Mechanical properties and microstructures
  12. 12. Characterization of precipitations
  13. 13. Formation of new austenite during aging
  14. 14. Conclusions</li></li></ul><li>Low carbon: ductile martensite<br />Compositions in mass%: classical maraging steel<br />Precipitation hardening<br />Expensive for automotive applications !<br />Optimised for very high strength + toughness<br />We want high strength + ductility<br />
  15. 15. Low carbon: ductile martensite<br />Compositions in mass%: newlean maraging steels<br />PH<br />PH<br />PH<br />Precipitation Hardenable<br />Mn (+Ni): austenite (TRIP)<br />Raabe, Ponge, Dmitrieva, Sander: Adv. Eng. Mat. 11 (2009) 547<br />
  16. 16. Processing<br />Vacuuminductionmelting<br />Annealing<br />Hot deformation<br />Solution heat treatment<br />+ retained austenite<br />Quenching<br />Martensite<br />“Maraging“<br />retained + new austenite<br />Aging (450°C)<br />Dmitrieva et al. ActaMater 59 (2011)<br />
  17. 17. Overview<br /><ul><li>Introduction
  18. 18. Compositions and processing
  19. 19. Mechanical properties and microstructures
  20. 20. Characterization of precipitations
  21. 21. Formation of new austenite during aging
  22. 22. Conclusions</li></li></ul><li>Hardness during aging at 450°C<br />12MnPH<br />09MnPH<br />15MnPH<br />12MnPH<br />g<br />09MnPH<br />a’<br />15MnPH<br />Dmitrieva et al. ActaMater 59 (2011)<br />
  23. 23. 12MnPH after aging (48h 450°C)<br />precipitates in a`<br />no precipitates in<br />Dmitrieva et al. ActaMater 59 (2011)<br />
  24. 24. Tensile tests<br />Ni-Maraging<br />aged (450°C/48h)<br />(X3NiCoMoTi18-12-4)<br />quenched<br />12MnPH<br />aged (450°C/48h)<br />quenched<br />D. Raabe et al. ScriptaMaterialia 60 (2009) 1141<br />
  25. 25. Overview<br /><ul><li>Introduction
  26. 26. Compositions and processing
  27. 27. Mechanical properties and microstructures
  28. 28. Characterization of precipitations
  29. 29. Formation of new austenite during aging
  30. 30. Conclusions</li></li></ul><li>Atom Probe, 12MnPH aged (48h, 450°C)<br />Ni<br />a‘+particles<br />g (noparticles)<br />Mn<br />enrichment in interface ? <br />Dmitrieva et al. ActaMater 59 (2011)<br />
  31. 31. 09MnPH aging at 450°C, Proxigrams<br />Fe<br />Fe<br />09MnPH<br />450°C/48h<br />09MnPH<br />450°C/192h<br />matrix<br />particle<br />matrix<br />particle<br />Ni<br />Ni<br />Mn<br />Mn<br />Al<br />Al<br />Ti<br />Ti<br />Dmitrieva et al. ActaMater 59 (2011)<br />
  32. 32. Chemical compositions (09MnPH; 450°C/48h)<br />47.11<br />Ni50(Mn,Al,Ti)50<br />possible:<br />Dmitrieva et al. ActaMater 59 (2011)<br />
  33. 33. 09MnPH aging at 450°C<br />48 hours<br />192 hours<br />Iso-conc. surfaces:<br />14 at.% Ni<br />only Feand Nishown<br />10 nm<br />Dmitrieva et al. ActaMater 59 (2011)<br />
  34. 34. Precipitations<br /><ul><li>After aging (48h 450°C) nanosizedprecipitationsin martensite (Ø ~ 5nm; volume fraction ~ 1.5%)
  35. 35. Heusler Alloy (Ni2MnAl)? B2 or L21?Coherent?Cut bydislocations?</li></li></ul><li>Overview<br /><ul><li>Introduction
  36. 36. Compositions and processing
  37. 37. Mechanical properties and microstructures
  38. 38. Characterization of precipitations
  39. 39. Formation of new austenite during aging
  40. 40. Conclusions</li></li></ul><li>Effectofaging on ductility<br />12MnPH<br />12 wt.% Mn, 0.01 wt.% C, 2 wt.% Ni, 1 wt.% Ti, 0.15 wt.% Al,1 wt.% Mo, 0.06 wt.% Si<br />TRIP effect<br />(austenite <br />transforms to martensite)<br />Maraging effect<br />(precipitation hardening <br />in martensite)<br />D. Raabe, D. Ponge, O. Dmitrieva, B. Sander,Scripta Mater. 60 (2009) 1141<br />D. Raabe, D. Ponge, O. Dmitrieva, B. Sander, Adv. Eng. Mater. 11/7 (2009) 547<br />
  41. 41. Effectofaging on ductility<br />aged 450°C/48h <br />Precipitation<br />hardening<br />2<br />as-quenched<br />increase of austenite<br />fraction during aging<br />-Fe (Martensite)<br />-Fe (Austenite), vol. fraction 15-20%<br />
  42. 42. Effectofaging on ductility<br />aged 450°C/48h <br />Precipitation<br />hardening<br />2<br />as-quenched<br />increase of austenite<br />fraction during aging<br />?<br />strain 0%<br />strain 15%<br />2<br />1<br />1<br />-Fe (Martensite)<br />-Fe (Austenite), vol. fraction 15-20%<br />
  43. 43. APT results: Atomic map (12MnPH aged 450°C/48h) <br />Martensite decorated by precipitations<br />Austenite<br />?<br />?<br />70 millionions<br />Laser mode<br />(0.4nJ, 54K)<br />Mn atoms, Ni atoms<br />Mn iso-conc: 18 at.%<br />
  44. 44. Overview<br /><ul><li>Introduction
  45. 45. Compositions and processing
  46. 46. Mechanical properties and microstructures
  47. 47. Characterization of precipitations
  48. 48. Formation of new austenite during aging
  49. 49. Conclusions</li></li></ul><li>Conclusions <br />Design of “Lean Maraging TRIP steel“ <br />Precipitationhardening<br />Increase strength<br />Austenite (retained + new)<br />Increase ductility<br /><ul><li>Martensitic Mn-steels (~0,01wt%C): good ductility
  50. 50. + controlled amounts of Ni (2 wt%), Al (0.15 wt%), … increase strength during aging by formation of nanosized precipitations without significant reduction of ductility
  51. 51. By controlling the austenite stability (here by Mn) martensite can be refined and ductility can be further increased by retained and reverted austenite (TRIP)</li>

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