Microstructural stability of 9--12%Cr ferrite/martensite heat-resistant steels

Abstract

The microstructural evolutions of advanced 9--12%Cr ferrite/martensite heat-resistant steels used for power generation plants are reviewed in this article. Despite of the small differences in chemical compositions, the steels share the same microstructure of the as-tempered martensite. It is the thermal stability of the initial microstructure that matters the creep behavior of these heat-resistant steels. The microstructural evolutions involved? in? 9--12%Cr ?ferrite ?heat-resistant ?steels ?are ?elabo- rated, including (1) martensitic lath widening, (2) disappearance of prior austenite grain boundary, (3) emergence of subgrains, (4) coarsening of precipitates, and (5) formation of new precipitates, such as Laves-phase and Z-phase. The former three microstructural evolutions could be retarded by properly disposing the latter two. Namely improving the stability of precipitates and optimizing their size distribution can effectively exert the beneficial influence of precipitates on microstructures. In this sense, the microstructural stability of the tempered martensite is in fact the stability of precipitates during the creep. Many attempts have been carried out to improve the microstructural stability of 9--12%Cr steels and several promising heat-resistant steels have been developed.

Keywords

heat-resistant steel / microstructure / martensite / precipitate / microstructural evolution

References

[1] Cerjak H, Hofer P, Schaffernak B. The influence of microstructural aspects on the service behaviour of advanced power plant steels. ISIJ International , 1999, 39(9): 874–888
[2] Masuyama F. History of power plants and progress in heat resistant steels. ISIJ International , 2001, 41(6): 612–625
[3] Maruyama K, Sawada K, Koike J. Strengthening mechanisms of creep resistant tempered martensitic steel. ISIJ International , 2001, 41(6): 641–653
[4] Agamennone R, Blum W, Gupta C, . Evolution of microstructure and deformation resistance in creep of tempered martensitic 9–12%Cr–2%W–5%Co steels. Acta Materialia , 2006, 54(11): 3003–3014
[5] Klueh R L, Nelson A T. Ferritic/martensitic steels for next-generation reactors. Journal of Nuclear Materials , 2007, 371(1–3): 37–52
[6] Klueh R L, Alexander D J, Sokolov M A. Effect of chromium, tungsten, tantalum and boron on mechanical properties of 5–9Cr–WVTaB steels. Journal of Nuclear Materials , 2002, 304(2–3): 139–152
[7] Abe F, Araki H, Noda T. The effect of tungsten on dislocation recovery and precipitation behavior of low-activation martensitic 9Cr steels. Metallurgical Transactions A , 1991, 22(10): 2225–2235
[8] Klueh R L, Alexander D J, Kenik E A. Development of low-chromium, chromium-tungsten steels for fusion. Journal of Nuclear Materials , 1995, 227(1–2): 11–23
[9] van der Schaaf B, Gelles D S, Jitsukawa S, . Progress and critical issues of reduced activation ferritic/martensitic steel development. Journal of Nuclear Materials , 2000, 283–287: 52–59
[10] Jitsukawa S, Tamura M, van der Schaaf B, . Development of an extensive database of mechanical and physical porperties for reduced-activation martensitic steel F82H. Journal of Nuclear Materials , 2002, 307–311: 179–186
[11] Huang Q Y, Li J G, Chen Y X. Study of irradiation effects in China low activation martensitic steel CLAM. Journal of Nuclear Materials , 2004, 329–333: 268–272
[12] Abe F, Nakazawa S. Microstructural evolution and creep behaviour of bainitic, martensitic and martensite-ferrite dual phase Cr–2W steels. Materials Science and Technology , 1992, 8(12): 1063–1069
[13] Liu X Y, Fujita T. Effect of chromium content on creep rupture properties of a high chromium ferritic heat resisting steel. ISIJ International , 1989, 29(8): 680–686
[14] Gustafson A, Agren J. Possible effect of Co on coarsening of M₂₃C₆ carbide and Orowan stress in a 9% Cr Steel. ISIJ International , 2001, 41(4): 356–360
[15] Abe F. Behavior of boron in 9Cr heat resistant steel during heat treatment and creep deformation. Key Engineering Materials , 2007, 345–346: 569–572
[16] Abe F, Semba H, Sakuraya T. Effect of boron on microstructure and creep deformation behavior of tempered martensitic 9Cr steel. Materials Science Forum , 2007, 539–543: 2982–2987
[17] Hattestrand M, Andren H O. Boron distribution in 9–12% chromium steels. Materials Science and Engineering A , 1999, 270(1): 33–37
[18] Ennis P J, Quadakkers J W. The steam oxidation resistance of 9–12% Cr steels. In: Lecomte-Beckers J, Carton M, Schubert F, ., eds. Materials for Advanced Power Engineering 2002: Proceedings of the 7th Liege Conference , 2002, 1131–1142
[19] Ishitsuka T, Inoue Y, Ogawa H.Effect of silicon on the steam oxidation resistance of a 9% Cr heat resistant steel. Oxidation of Metals , 2004, 61(1): 125–142
[20] Aghajani A, Somsen C, Eggeler G. On the effect of long-term creep on the microstructure of a 12% chromium tempered martensite ferritic steel. Acta Materialia , 2009, 57(17): 5093–5106
[21] Aghajani A, Richter F, Somsen C, . On the formation and growth of Mo-rich Laves-phase particles during long-term creep of a 12% chromium tempered martensite ferritic steel. Scripta Materialia , 2009, 61(11): 1068–1071
[22] Hosoi Y, Wade N, Kunimitsu S, . Precipitation behavior of Laves-phase and its effect on toughness of 9Cr–2Mo ferritic-martensitic steel. Journal of Nuclear Materials , 1986, 141–143: 461–467
[23] Abe F, Taneike M, Sawada K. Alloy design of creep resistant 9Cr steel using a dispersion of nano-sized carbonitrides. International Journal of Pressure Vessels and Piping , 2007, 84(1–2): 3–12
[24] Yoshizawa M, Igarashi M. Long-term creep deformation characteristics of advanced ferritic steels for USC power plants. International Journal of Pressure Vessels and Piping , 2007, 84(1–2): 37–43
[25] Kostka A, Tak K G, Hellmig R J, . On the contribution of carbides and micrograin boundaries to the creep strength of tempered martensite ferritic steels. Acta Materialia , 2007, 55(2): 539–550
[26] Ghassemi Armaki H, Chen R P, Maruyama K, . Creep behavior and degradation of subgrain structures pinned by nanoscale precipitates in strength-enhanced 5 to 12% Cr ferritic steels. Metallurgical and Materials Transactions A , 2011, 42(10): 3084–3094
[27] Blum W. In: Mughrabi H, ed. Plastic Deformation and Fracture of Materials . In: Cahn R W, Haasen P, Kramer E J, eds. Materials Science and Technology (Volumn. 6). Weinheim: VCH , 1993, 359–405
[28] Eggeler G, Blum W. Coarsening of the dislocation-structure after stress reduction during creep of NaCl single-crystals. Philosophical Magazine , 1981, 44(5): 1065–1084
[29] Sawada K, Taneike M, Kimura K, . In situ observation of recovery of lath structure in 9% chromium creep resistant steel. Materials Science and Technology , 2003, 19(6): 739–742
[30] Kimura K, Kushima H, Abe F, . Inherent creep strength and long term creep strength properties of ferritic steels. Materials Science and Engineering A , 1997, 234–236: 1079–1082
[31] Kimura K, Toda Y, Kushima H, . Creep strength of high chromium steel with ferrite matrix. International Journal of Pressure Vessels and Piping , 2010, 87(6): 282–288
[32] Panait C G, Bendick W, Fuchsmann A, . Study of the microstructure of the Grade 91 steel after more than 100,000 h of creep exposure at 600°C. International Journal of Pressure Vessels and Piping , 2010, 87(6): 326–335
[33] Abe F. Bainitic and martensitic creep-resistant steels. Current Opinion in Solid State and Materials Science , 2004, 8(3–4): 305–311
[34] Hu P, Yan W, Sha W, . Microstructure evolution of a 10Cr heat-resistant steel during high temperature creep. Journal of Materials Science & Technology , 2011, 27(4): 344–351
[35] Sawada K, Maruyama K, Hasegawa Y, . Creep life assessment of high chromium ferritic steels by recovery of martensitic lath structure. Key Engineering Materials , 2000, 171–174: 109–114
[36] Abe F, Nakazawa S, Araki H, . The role of microstructural instability on creep-behavior of a martensitic 9Cr–2W steel. Metallurgical Transactions A , 1992, 23(2): 469–477
[37] Dimmler G, Weinert P, Kozeschnik E, . Quantification of the Laves-phase in advanced 9–12% Cr steels using a standard SEM. Materials Characterization , 2003, 51(5): 341–352
[38] Eggeler G, Nilsvang N, Ilschner B. Microstructural changes in a 12%Cr steel during creep. Steel Research , 1987, 58(2): 97–103
[39] Eggeler G, Earthman J C, Nilsvang N, . Microstructural study of creep rupture in a 12% chromium ferritic steel. Acta Metallurgica , 1989, 37(1): 49–60
[40] Dronhofer A, Pesicka J, Dlouhy A, . On the nature of internal interfaces in tempered martensite ferritic steels. Zeitschrift fur Metallkunde , 2003, 94(5): 511–520
[41] Tak K-G, Schulz U, Eggeler G. On the effect of micrograin crystallography on creep of FeCr alloys. Materials Science and Engineering A , 2009, 510–511: 121–129
[42] Pesicka J, Kuzel R, Dronhofer A, . The evolution of dislocation density during heat treatment and creep of tempered martensite ferritic steels. Acta Materialia , 2003, 51(16): 4847–4862
[43] Pesicka J, Dronhofer A, Eggeler G. Free dislocations and boundary dislocations in tempered martensite ferritic steels. Materials Science and Engineering A , 2004, 387–389: 176–180
[44] Kostka A, Tak K G, Hellmig R J, . On the contribution of carbides and micrograin boundaries to the creep strength of tempered martensite ferritic steels. Acta Materialia , 2007, 55(2): 539–550
[45] Keller C, Margulies M M, Hadjem-Hamouche Z, . Influence of the temperature on the tesile behaviour of a modified 9Cr–1Mo T91 martensitic steel. Materials Science and Engineering A , 2010, 527(24–25): 6758–6764
[46] Qin Y, G?tz G, Blum W. Subgrain structure during annealing and creep of the cast martensitic Cr-steel G-X12CrMoWVNbN 10-1-1. Materials Science and Engineering A , 2003, 341(1–2): 211–215
[47] Blum W, G?tz G. Evolution of dislocation structure in martensitic steels: the subgrain size as a sensor for creep strain and residual creep life. Steel Research , 1999, 70(7): 274–278
[48] Hald J, Korcakova L. Precipitate stability in creep resistant ferritic steels — Experimental investigations and modelling. ISIJ International , 2003, 43(3): 420–427
[49] Polcik P, Sailer T, Blum W, . On the microstructural development of the tempered martensitic Cr-steel P 91 during long-term creep — a comparison of data. Materials Science and Engineering A , 1999, 260(1–2): 252–259
[50] Panait C G, Zielińska-Lipiec A, Koziel T, . Evolution of dislocation density, size of subgrains and MX-type precipitatesin a P91 steel during creep and during thermal ageing at 600°C for more than 100,000 h. Materials Science and Engineering A , 2010, 527(16–17): 4062–4069
[51] Eggeler G. The effect of long-term creep on particle coarsening in tempered martensite ferritic steels. Acta Metallurgica , 1989, 37(12): 3225–3234
[52] Sawada K, Taneike M, Kimura K, . Effect of nitrogen content on microstructural aspects and creep behavior in extremely low carbon 9Cr heat-resistant steel. ISIJ International , 2004, 44(7): 1243–1249
[53] Ghassemi-Armaki H, Chen R P, Maruyama K, . Static recovery of tempered lath martensite microstructures during long-term aging in 9–12% Cr heat resistant steels. Materials Letters , 2009, 63(28): 2423–2425
[54] Abe F. Effect of quenching, tempering, and cold rolling on creep deformation behavior of a tempered martensitic 9Cr–1W steel. Metallurgical Transactions A , 2003, 34(4): 913–925
[55] Abe F, Nakazawa S. The effect of tungsten on creep — behavior of tempered martensitic 9Cr steels. Metallurgical Transactions A , 1992, 23(11): 3025–3034
[56] Aghajani A, Somsen Ch, Pesicka J, . Microstructural evolution in T24, a modified 2(1/4)Cr–1Mo steel during creep after different heat treatments. Materials Science and Engineering A , 2009, 510–511: 130–135
[57] Bendick W, Gabrel J, Hahn B, . New low alloy heat resistant ferritic steels T/P23 and T/P24 for power plant application. International Journal of Pressure Vessels and Piping , 2007, 84(1–2): 13–20
[58] Bhandarkar M D, Bhat M S, Parker E R, . Creep and fracture of a Laves-phase strengthened ferritic alloy. Metallurgical Transactions A , 1976, 7(5): 753–760
[59] Cui J, Kim I-S, Kang C-Y, . Creep stress effect on the precipitation behavior of Laves-phase in Fe–10%Cr–6%W alloys. ISIJ International , 2001, 41(4): 368–371
[60] Sawada K, Takeda M, Maruyama K, . Effect of W on recovery of lath structure during creep of high chromium martensitic steels. Materials Science and Engineering A , 1999, 267(1): 19–25
[61] Kne?evi? V, Balun J, Sauthoff G, . Design of martensitic/ferritic heat-resistant steels for application at 650°C with supporting thermodynamic modelling. Materials Science and Engineering A , 2008, 477(1–2): 334–343
[62] Li Q. Precipitation of Fe₂W Laves-phase and modeling of its direct influence on the strength of a 12Cr–2W steel. Metallurgical and Materials Transactions A , 2006, 37(1): 89–97
[63] Porter D A, Easterling K E. Phase Transformation in Metals and Alloys . New York: Van Nostrand Reinhold, 1981: 326–332
[64] Hofer P, Cerjak H, Warbichler P. Quantitative evaluation of precipitates in the martensitic cast steel G-X12CrMoWVNbN10-1-1. In: Lecomte-Beckers J, Schubert F, Ennis P J, eds. 6th Liège- Conference Materials for Advanced Power Engineering , 1998, Part I, 549–557
[65] Foldyna V, Kubon Z, Filip M, . Evaluation of structural stability and creep resistance of 9–12% Cr steel. Steel Research , 1996, 67(9): 375–381
[66] Kubon Z, Foldyna V. The effect of Nb, V, N and Al on creep rupture strength of 9–12% Cr steel. Steel Research , 1995, 66(9): 389–393
[67] Hattestrand M, Andren H O. Microstructural development during ageing of an 11% chromium steel alloyed with copper. Materials Science and Engineering A , 2001, 318(1–2): 94–101
[68] Hu P, Yan W, Sha W, . Study on Laves-phase in an advanced heat-resistant steel. Frontiers of Materials Science in China , 2009, 3(4): 434–441
[69] Janovec J, Richarz B, Grabke H J. Some aspects of intermetallic phase precipitation in a 12% Cr-steel. Scripta Metallurgica et Materialia , 1995, 33(2): 295–300
[70] Dimmler G, Weinert P, Kozeschnik E, . Quantification of the Laves-phase in advanced 9–12% Cr steels using a standard SEM. Materials Characterization , 2003, 51(5): 341–352
[71] Hattestrand M, Schwind M, Andren H O. Microanalysis of two creep resistant 9–12% chromium steels. Materials Science and Engineering A , 1998, 250(1): 27–36
[72] Lundin L M. Direct measurement of carbon solubility in the intermetallic (Fe, Cr)₂(Mo, W) Laves-phase using atom-probe field-ion microscopy. Scripta Materialia , 1996, 34(5): 741–747
[73] Hosoi Y, Wade N, Kunimitsu S, . Precipitation behavior of Laves-phase and its effect on toughness of 9Cr–2Mo ferritic martensitic steel. Journal of Nuclear Materials , 1986, 141–143: 461–467
[74] Lee J S, Armaki H G, Maruyama K, . Causes of breakdown of creep strength in 9Cr–1.8W–0.5Mo–V–NbSteel. Materials Science and Engineering A , 2006, 428(1–2): 270–275
[75] Kunimitsu S, You Y, Kasuya N, . Effect of thermo-mechanical treatment on toughness of 9Cr–W ferritic-martensitic steels during aging. Journal of Nuclear Materials , 1991, 179–181: 689–692
[76] Schafer L. Tensile and impact behavior of the reduced-activation steels OPTIFER and F82H mod. Journal of Nuclear Materials , 2000, 283–287: 707–710
[77] Tamura M, Hayakawa H, Yoshitake A, . Phase stability of reduced activation ferritic steel: 8%Cr–2%W–0.2%V–0.04%Ta–Fe. Journal of Nuclear Materials , 1988, 155–157: 620–625
[78] Ishii T, Fukaya K, Nishiyama Y, . Low cycle fatigue properties of 8Cr–2WVTa ferritic steel at elevated temperatures. Journal of Nuclear Materials , 1998, 258(263): 1183–1186
[79] Fernandez P, Hernandez-Mayoral M, Lapena J, . Correlation between microstructure and mechanical properties of reduced activation modified F-82H ferritic martensitic steel Materials. Materials Science and Technology , 2002, 18(11): 1353–1362
[80] Miyata K, Sawaragi Y, Okada H, . Microstructural evolution of a 12Cr–2W–Cu–V–Nb steel during three-year service exposure. ISIJ International , 2000, 40(11): 1156–1163
[81] Tsuchida Y, Okamoto K, Tokunaga Y. Improvement of creep rupture strength of high Cr ferritic steel by addition of W. ISIJ International , 1995, 35(3): 317–323
[82] Sato M, Hasegawa Y, Muraki T, . Correlation between creep strength and stability of subgrain structure in high chromium ferritic heat resistant steel with tungsten. Journal of the Japan Institute of Metals , 2000, 64: 371–374
[83] Muneki S, Igarashi M, Abe F. Creep characteristics of precipitation hardened carbon free martensitic alloys. Key Engineering Materials , 2000, 171–174: 491–498
[84] Abe F. Creep rates and strengthening mechanisms in tungsten-trengthened 9Cr steels. Materials Science and Engineering A , 2001, 319–321: 770–773
[85] Danielsen H K, Hald J. Behaviour of Z phase in 9–12%Cr steels. Energy Materials , 2006, 1(1): 49–57
[86] Jack D H, Jack K H. Structure of Z-phase NbCrN. Journal of the Iron and Steel Institute , 1972, 210: 790–792
[87] Andren H O, Henjered A, Karlsson L. In: Stainless Steel 84. London: The Institute of Metals , 1985, 91–96
[88] Hald J, Danielsen H K. Z-phase strengthened martensitic 9–12%Cr steels. In: Proceedings of 3rd Symposium on Heat Resistant Steels and Alloys for High Efficiency USC Power Plants, National Institute for Materials Science , Tsukuba, Japan, 2009
[89] Danielsen H K, Hald J.A thermodynamic model of the Z-phase Cr(V, Nb)N. Calphad , 2007, 31(4): 505–514
[90] Danielsen H K, Hald J, Somers M A J. Atomic resolution imaging of precipitate transformation from cubic TaN to tetragonal CrTaN. Scripta Materialia , 2012, 66(5): 261–264
[91] Danielsen H K, Hald J. On the nucleation and dissolution process of Z-phase Cr(V, Nb)N in martensitic 12%Cr steels. Materials Science and Engineering A , 2009, 505(1–2): 169–177
[92] Sawada K, Kushima H, Kimura K, . TTP diagrams of Z phase in 9–12% Cr heat-resistant steels. ISIJ International , 2007, 47(5): 733–739
[93] Cipolla L, Danielsen H K, Venditti D, . Conversion of MX nitrides to Z-phase in a martensitic 12% Cr steel. Acta Materialia , 2010, 58(2): 669–679
[94] Hald J. Microstructure and long-term creep properties of 9–12% Cr steels. International Journal of Pressure Vessels and Piping , 2008, 85(1–2): 30–37
[95] Danielsen H K, Hald J. Tantalum-containing Z-phase in 12%Cr martensitic steels. Scripta Materialia , 2009, 60(9): 811–813
[96] Golpayegani A, Andrén H O, Danielsen H, . A study on Z-phase nucleation in martensitic chromium steels. Materials Science and Engineering A , 2008, 489(1–2): 310–318
[97] Yin F-S, Jung W-S, Chung S-H. Microstructure and creep rupture characteristics of an ultra-low carbon ferritic/martensitic heat-resistant steel. Scripta Materialia , 2007, 57(6): 469–472
[98] Strang A, Vodarek V. Z phase formation in martensitic 12CrMoVNb steel. Materials Science and Technology , 1996, 12(7): 552–556
[99] de Castro V, Leguey T, Munoz A, . Mechanical and microstructural behaviour of Y₂O₃ ODS EUROFER 97. Journal of Nuclear Materials , 2007, 367–37(Part A): 196–201
[100] Olier P, Bougault A, Alamo A, . Effects of the forming processes and Y₂O₃ content on ODS-Eurofer mechanical properties. Journal of Nuclear Materials , 2009, 386–388: 561–563
[101] Klimenkov M, Lindau R, Moslang A. New insights into the structure of ODS particles in the ODS-Eurofer alloy. Journal of Nuclear Materials , 2009, 386–388: 553–556
[102] Schaeublin R, Leguey T, Spatig P, . Microstructure and mechanical properties of two ODS ferritic/martensitic steels. Journal of Nuclear Materials , 2002, 307–311: 778–782
[103] Yu G, Nita N, Baluc N. Thermal creep behaviour of the EUROFER 97 RAFM steel and two European ODS EUROFER 97 steels. Fusion Engineering and Design , 2005, 75–79: 1037–1041
[104] Liu F, Fors D H R, Golpayegani A, . Effect of boron on carbide coarsening at 873 K (600°C) in 9–12% chromium steels. Metallurgical and Materials Transactions A , 2012, 43(11): 4053–4062
[105] Taneike M, Abe F, Sawada K. Creep-strengthening of steel at high temperatures using nano-sized carbonitride dispersions. Nature , 2003, 424(6946): 294–296
[106] Hald J, Straub S. In: Lecomte-Beckers J, ., eds. Materials for Advanced Power Engineering . Julich: Forschungszentrum Julich GmbH, 1998, 155
[107] Taneike M, Sawada K, Abe F. Effect of carbon concentration on precipitation behavior of M₂₃C₆ carbides and MX carbonitrides in martensitic 9Cr steel during heat treatment. Metallurgical and Materials Transactions A , 2004, 35(4): 1255–1262
[108] Grobner P J, Bi?s V, Sponseller D L. Delta ferritic heat-resistant chromium-molybdenum steels with improved rupture strength. Metallurgical and Materials Transactions A , 1980, 11(7): 909–917
[109] Toda Y, Iijima M, Kushima H, . Effects of Ni and heat treament on long-term creep strength of precipitation strengthened 15Cr ferritic heat resistant steels. ISIJ International , 2005, 45(11): 1747–1753