Effect of Heat Treatment on Microstructure and Hardness of Grade 91 Steel
Abstract
:1. Introduction
2. Experimental Details
2.1. Material
Element | Nominal | Measured |
---|---|---|
Cr | 8.00–9.50 | 8.55 |
Mo | 0.85–1.05 | 0.88 |
V | 0.18–0.25 | 0.21 |
Nb | 0.06–0.10 | 0.08 |
C | 0.08–0.12 | 0.10 |
Mn | 0.30–0.60 | 0.51 |
Cu | 0.4 (max.) | 0.18 |
Si | 0.20–0.50 | 0.32 |
N | 0.03–0.07 | 0.035 |
Ni | 0.40 (max.) | 0.15 |
P | 0.02 (max.) | 0.012 |
S | 0.01 (max.) | 0.005 |
Ti | 0.01 (max.) | 0.002 |
Al | 0.02 (max.) | 0.007 |
Zr | 0.01 (max.) | 0.001 |
Fe | Balance | Balance |
2.2. Heat Treatment
2.3. Metallographic Characterization
2.4. Thermodynamic Modeling
2.5. Differential Scanning Calorimetry
3. Results
3.1. Microstructural Characteristics
3.2. Hardness of Heat Treated Steel
3.3. Differential Scanning Calorimetry
Description of Phase Change | Temperature (°C) |
---|---|
α′ + M23C6 + (V,Nb)(N,C) + Z-phase → α + M23C6 + (V,Nb)(N,C) + Z-phase | 550 |
Tc (Curie Temperature) | 741 |
α + M23C6 + (V,Nb)(N,C) + Z-phase → α + M23C6 + (V,Nb)(N,C) + (Nb,V)(C,N) | 770 |
α + M23C6 + (V,Nb)(N,C) + (Nb,V)(C,N) → α + γ + (V,Nb)(N,C) + (Nb,V)(C,N) + M23C6 | 820 (Ac1) |
α + γ + (V,Nb)(N,C) + (Nb,V)(C,N) + M23C6 → γ + (V,Nb)(N,C) + (Nb,V)(C,N) | 870 (Ac3) |
γ + (V,Nb)(N,C) + (Nb,V)(C,N) → γ + (Ti,Nb)(N,C) + (Nb,V)(C,N) | 1045 |
γ + (Ti,Nb)(N,C) + (Nb,V)(C,N) → δ + γ + (Ti,Nb)(N,C) | 1270 |
δ + γ + (Ti,Nb)(N,C) → γ + δ | 1397 |
Martensite start (Ms) | 380 |
3.4. Thermo-Calc Calculations
4. Discussion
4.1. As-Normalized Microstructure
4.2. Tempered Microstructure
4.3. DSC Study
4.4. Thermo-Calc Calculations
5. Conclusions
Acknowledgments
Author Contributions
Conflicts of Interest
References
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Shrestha, T.; Alsagabi, S.F.; Charit, I.; Potirniche, G.P.; Glazoff, M.V. Effect of Heat Treatment on Microstructure and Hardness of Grade 91 Steel. Metals 2015, 5, 131-149. https://doi.org/10.3390/met5010131
Shrestha T, Alsagabi SF, Charit I, Potirniche GP, Glazoff MV. Effect of Heat Treatment on Microstructure and Hardness of Grade 91 Steel. Metals. 2015; 5(1):131-149. https://doi.org/10.3390/met5010131
Chicago/Turabian StyleShrestha, Triratna, Sultan F. Alsagabi, Indrajit Charit, Gabriel P. Potirniche, and Michael V. Glazoff. 2015. "Effect of Heat Treatment on Microstructure and Hardness of Grade 91 Steel" Metals 5, no. 1: 131-149. https://doi.org/10.3390/met5010131