 Formed when steel is cooled rapidly enough from
Austenitizing temperature by passing the nose of the c-curve
and kept ...
Fig 1. Fig 2.
ferrite
cementite
 Process of formation:- Austenitization of steel at ~950 °c followed
by transfer into an oven at the low temperature say...
 Achieve strength in excess of 2.5 Gpa.
 Toughness ~30 Mpa.m1/2
 The Bainite obtained by low temperature
transformat...
Steel
Sample
Temp
.
Bainite
lathe
thickness
/nm
Retained
ausetnite
/%
Hardness
/hv
Ys/mpa Uts/mpa El./%
0.8 ...
 Yield strength were found to correlate well with the
microstructure.
 By Mack & Bartlett :
o For a thickness ‘t’ of ...
 Weakness:-
 It cannot be satisfactorily welded.
 Restricted applications.
 Applications :
 Different military in...
Thank
you
Nano structured bainite
Nano structured bainite
Nano structured bainite
Nano structured bainite
of 13

Nano structured bainite

nano structure bainite
Published on: Mar 3, 2016
Published in: Technology      
Source: www.slideshare.net


Transcripts - Nano structured bainite

  • 1.  Formed when steel is cooled rapidly enough from Austenitizing temperature by passing the nose of the c-curve and kept isothermally at constant temperature .  Formed at a temperature range (250-550) °c.  Based on the quenching temperature it is devided into two 1. Upper Bainite ( formed between 550-350 °c , and has a morphology of feathery shaped ferrite). 2. Lower Bainite ( formed between temperature below 350 °c , and has a morphology of plate-like structure ).
  • 2. Fig 1. Fig 2.
  • 3. ferrite cementite
  • 4.  Process of formation:- Austenitization of steel at ~950 °c followed by transfer into an oven at the low temperature say ~200 ° c to be held there for 10 days or so.  No rapid cooling is needed ,residual stresses are avoided.  With careful alloy design, Bainite transformation can be made possible at temperatures as low as 125 ° c.  The sample must be large enough because the time taken to reach 200 °c from the Austenization temperature is much less than that required to initiate Bainite.  Some amount of residual Austenite is important because it enhances the work hardening capacity of material.
  • 5.  Achieve strength in excess of 2.5 Gpa.  Toughness ~30 Mpa.m1/2  The Bainite obtained by low temperature transformation is harder then ever achieved and will have better wear resistance.
  • 6. Steel Sample Temp . Bainite lathe thickness /nm Retained ausetnite /% Hardness /hv Ys/mpa Uts/mpa El./% 0.8 c 220°c 35 16 710 1865 2444 4.9 0.8 c 250°c 37 18 659 1810 2345 6.6 0.8 c 270°c 24 24 615 1658 2226 10.2 1CSi 220°c 28 36 650 1626 2488 8.1 1CSi 250°c 28 34 625 1642 2417 17.2
  • 7.  Yield strength were found to correlate well with the microstructure.  By Mack & Bartlett : o For a thickness ‘t’ of the ferrite plates the mean intercept L=2t o By Langford and Cohen Strength is given by =115/L Mpa , where ‘L’ is in micrometer.
  • 8.  Weakness:-  It cannot be satisfactorily welded.  Restricted applications.  Applications :  Different military industries such as armor.  Car manufacturing such as shaft , bearings.  Railway industries.
  • 9. Thank you

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