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The effect of bainite morphology on the mechanical properties of a high bainite dual phase (HBDP) steel

Bakhtiari, R ; Sharif University of Technology | 2009

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  1. Type of Document: Article
  2. DOI: 10.1016/j.msea.2009.07.042
  3. Publisher: 2009
  4. Abstract:
  5. 4340 steel bars were austenitized at 850 °C for 1 h followed by heating at 700 °C for 90 min and quenching into a salt bath at the temperature range of 300-450 °C for 1 h to obtain dual structures with 34 vol.% fraction ferrite and various bainite morphologies. SEM studies showed that by increasing the austempering temperature, bainite morphology varies from lower to upper bainite. Tensile, impact and hardness tests revealed that increasing the austempering temperature from 300 to 400 °C leads to a reduction in yield and ultimate tensile strength, hardness, uniform and total elongation and impact energy. But in dual phase steel produced by austempering at 450 °C, yield and tensile strength and hardness increased and severe reduction in total elongation and impact energy obtained. Fractography of tensile specimens showed brittle behavior for this austempering temperature. Fatigue test results showed that fatigue limit decreases with increasing austempering temperature from 300 to 400 °C. Finally, fractography studies showed cleavage fracture at the surface of fatigue specimens austempered at 400 °C, which confirms the tendency to brittle behavior. © 2009 Elsevier B.V. All rights reserved
  6. Keywords:
  7. Austempering ; Austempering temperature ; Brittle behavior ; Cleavage fracture ; Dual phase ; Dual-phase steel ; Fatigue Limit ; Fatigue specimen ; Fatigue tests ; Hardness test ; Impact energy ; Lower bainite ; Salt bath ; SEM study ; Steel bars ; Temperature range ; Tensile specimens ; Total elongations ; Ultimate tensile strength ; Upper bainite ; Yield and tensile strength ; Brittle fracture ; Fatigue crack propagation ; Fatigue testing ; Ferrite ; Fractography ; Fracture mechanics ; Hardness ; Hardness testing ; Impact strength ; Mechanical properties ; Morphology ; Quenching ; Sheet metal ; Steel ; Tensile strength ; Bainite
  8. Source: Materials Science and Engineering A ; Volume 525, Issue 1-2 , 2009 , Pages 159-165 ; 09215093 (ISSN)
  9. URL: https://www.sciencedirect.com/science/article/abs/pii/S0921509309008193