Effects of phosphorus grain boundary segregation and hardness on the ductile-to-brittle transition for a 2.25Cr1Mo steel

Abstract

The combined effect of phosphorus grain boundary segregation and hardness on the ductile-to-brittle transition was examined for a P-doped 2.25Cr1Mo steel by using Auger electron spectroscopy in conjunction with hardness measurements, Charpy impact tests and scanning electron microscopy. With prolonging time at 540 °C after water quenching from 980 °C, the segregation of phosphorus increases and the hardness decreases. The DBTT (FATT) increases with increasing phosphorus segregation and decreases with decreasing hardness. The effect of phosphorus segregation is dominant until 100 h aging and after that the hardness effect becomes dominant. This effect makes the DBTT (FATT) decrease with further prolonging ageing time although the segregation of phosphorus still increases strongly.

Keywords

segregation / grain boundary / high strength low alloy steel / embrittlement / fracture

References

[1] Phythian W. J., English C. A. Microstructural Evolution in Reactor Pressure Vessel Steels[J]. J. Nucl. Mater., 1993, 205: 162-177.

[2] Mulford R. A., McMahon C. Jr, Pope D. P., Feng H. C. Temper Embrittlement of Ni-Cr Steel by Antimony-3. Effects of Ni and Cr[J]. Metall. Trans. A, 1976, 7A(9): 1 269-1 274.

[3] Yu J., McMahon C. J. Jr. Effects of Composition and Carbide Precipitation on Temper Embrittlement of 2.25Cr-1Mo Steel-1. Effects of P and Sn[J]. Metall. Trans. A, 1980, 11(2): 277-289.

[4] Norris S. D. Influence of Non-metallic Inclusions on the Prediction of 50 FATT Using the Miniaturized Disk Bend Testa[J]. Int. J. Pressure Vessels Piping, 1997, 74(3): 249-258.

[5] Holzmann M., Vlach B., Man J. Role of Cleavage Fracture Stress in Upper-nose Temper Embrittlement of 2.25Cr-1Mo Low Alloy Steel[J]. Scripta Metall. Mater., 1992, 26(4): 615-620.

[6] Holzmann M., Vlach B., Man J., Krejci J. Influence of Tempering on Cleavage Fracture Stress and Transition Behaviour of Bainitic 2.25Cr1Mo Steel[J]. Steel Research, 1995, 66(6): 264-271.

[7] Davis L. E., McDonald M. C., Palmberg P. W., Riach G. E., Weber R. E. Handbook of Auger Electron Spectroscopy, 2nd ed. Physical Electronics Division[M], 1976. Minnesota: Perkin-Elmer Corporation.

[8] Tuominen S. M., Clough S. P. Grain Boundary Segregation of Sulphur and Nitrogen in Sintered Molybdenum[J]. Metall. Trans. A, 1979, 10A(1): 127-129.

[9] McLean D. Grain Boundaries in Metals[M], 1957. Oxford: Clarendon Press.

[10] Peterson N. L. Grain-boundary Diffusion in Metals[J]. Int. Met. Rev., 1983, 28(2): 65-91.

[11] Demoulin P., Guttmann M., Palmier M., . Role of Mo in P-Induced Temper Embrittlement[J]. Met. Sci., 1980, 14(1): 1-15.

[12] Dieter G. E. Mechanical Metallurgy, 2nd ed[M], 1988. London.: McGraw-Hill Book Co..

[13] Seah M. P. Adsorption-Induced Interface Decohesion[J]. Acta Metall., 1980, 28(7): 955-962.

[14] Lee D. Y., Barrera E. V., Stark J. P., Marcus H. L. Influence of Alloying Elements on Impurity Induced Grain Boundary Embrittlement[J]. Metall. Trans. A, 1984, 15A(7): 1 415-1 430.

[15] Tanino M., Liu C. M. Grain Boundary Embrittlemet in Iron Alloys, an AES and AP-FIM Study[J]. ANNALES DE PHYSIQUE, 1995, 20(3): 93-100.

[16] Mulford R. A., McMahon C. J. Jr, Pope D. P., Feng H. C. Temper Embrittlement of Ni-Cr Steels by Phosphorus[J]. Metall. Trans. A, 1976, 7A(8): 1 183-1 195.

[17] Ucisik A. H., McMahon C. J. Jr, Feng H. C. Influence of Intercritical Heat Treatment on the Temper Embrittlement Susceptibility of a P-doped Ni-Cr Steel[J]. Metall. Trans. A, 1978, 9A(3): 321-329.

[18] Takayama S., Ogura T., Fu S. C., McMahon C. J. Jr. The Calculation of Transition Temperature Changes in Steels due to Temperature Embrittlement[J]. Metall. Trans. A, 1980, 11A(9): 1 513-1 530.

[19] Christien F., Le Gall R., Saindrenan G. Synergistic Effect of Hardness and Phosphorus Grain Boundary Segregation on the Ductile-to-Brittle Transition Temperature of 17-4 PH Steel[J]. Metall. Mater. Trans. A, 2003, 34A(11): 2 483-2 491.

[20] Ogura T. Method for Evaluation of the Amount of Grain Boundary Segregation during Quenching[J]. Trans. Jpn. Inst. Met., 1981, 22(2): 109-117.

[21] Menyhard M., McMahon C. J. Jr. On the Effect of Molybdnum in the Embrittlement of Phosphorus-doped Iron[J]. Acta Metall., 1989, 37: 2 287

[22] Sevc P., Janovec J., Koutnik M. A Vyrostkova. Equilibrium Grain Boundary Segregation of Phosphorus in 2.6Cr-0.7Mo-0.3V Steels[J]. Acta Metall. Mater., 1995, 43(1): 251-258.

[23] Janovec J., Grman D., Perhacova J., . Thermodynamics of Phosphorus Grain Boundary Segregation in Polycrystalline Low Alloy Steels[J]. Surf. Interface Anal., 2000, 30(1): 354-358.

[24] Perhacova J., Vyrostkova A., Sevc P., Janovec J., Crabke H. J. Phosphorus Segregation in CrMoV Low-alloy steels[J]. Surf. Sci., 2000, 454(1): 642-646.

[25] Perhacova J., Grman D., Svoboda M., . Microstructural Aspects of Phosphorus Grain Boundary Segregation in Low Alloy Steels[J]. Mater. Lett., 2001, 47(1–2): 44-49.

[26] Sevc P., Janovec J., Katana V. On Kinetics of Phosphorus Segregation in Cr-Mo-V Low Alloy Steel Scripta Metall[J]. Mater., 1994, 31(12): 1 673-1 678.

[27] Erhart H., Grabke H. J. Equilibrium Segregation of Segregation of Phosphorus at Grain Boundaries of Fe-P, Fe-C-P, Fe-Cr-P, and Fe-Cr-C-P Alloys[J]. Met. Sci., 1981, 15(9): 401-408.

[28] Lejcek P., Hofmann S. Prediction of Enthalpy and Entropy of Grain Boundary Segregation[J]. Surf. Interface Anal., 2002, 33(3): 203-210.