Skip to main content Accessibility help

Study on the microstructure and toughness of dissimilarly welded joints of advanced 9Cr/CrMoV

  • Runqi Lin (a1), Haichao Cui (a1), Fenggui Lu (a1), Xin Huo (a2) and Peng Wang (a2)...


Dissimilar joints of advanced 9Cr/CrMoV have been successfully welded by narrow gap submerged arc welding using multi-layer and multi-pass techniques. The objective of our study is to establish the correlation between impact toughness and microstructural characteristics of the welded joints. Impact toughness tests were conducted in a wide range of temperature from −60 °C to 80 °C for different regions in the dissimilar joints. The fracture appearance transition temperature of base metal of 9Cr, CrMoV and weld metal were tested as 23 °C, −9 °C and −2 °C respectively, which all satisfied the service requirement. Optical microscope and scanning electron microscope revealed that weld metal and base metal of CrMoV comprised martensite and bainite while 9Cr was composed of lath martensite. The low toughness in the latter region arose from large grains with excessive carbide precipitates. Nonuniform microstructure in the heat-affected zone of 9Cr side caused different crack propagation paths and subsequently led to large variations of absorbed energy. When crack propagates along carbon-enriched zone in heat affected zone, the absorbed energy was 48 J. With crack deviating far from carbon-enriched zone, the absorbed energy increased to 147 J. Examination on fracture surfaces revealed the typical brittle fracture appearance in 9Cr and inter-granular fracture mode in heat-affected zone of 9Cr side when crack propagated along carbon-enriched zone.


Corresponding author

a) Address all correspondence to this author. e-mail:


Hide All
1. Poules, H.: Advantages of ultra super critical technology in power generation. Presented at the International Conference on Clean Coal Technologies for our Future CCT, 10, 2005.
2. Liu, X.J., Kong, X.B., Hou, G.L., and Wang, J.H.: Modeling of a 1000 MW power plant ultra super-critical boiler system using fuzzy-neural network methods. Energy Convers. Manage. 65, 518 (2013).
3. Kosman, W.: Thermal analysis of cooled supercritical steam turbine components. Energy 35(2), 1181 (2010).
4. Huo, W., Li, J., and Yan, X.: Effects of coolant flow rates on cooling performance of the intermediate pressure stages for an ultra-supercritical steam turbine. Appl. Therm. Eng. 62(2), 723 (2014).
5. Kosman, W., Roskosz, M., and Nawrat, K.: Thermal elongations in steam turbines with welded rotors made of advanced materials at supercritical steam parameters. Appl. Therm. Eng. 29(16), 3386 (2009).
6. Narula, R., Koza, D., and Wen, H.: Impacts of steam conditions on plant materials and operation in ultra-supercritical coal power plants. In Ultra-Supercritical Coal Power Plants: Materials, Technologies and Optimisation, D. Zhang, ed. (Woodhead Publishing, Cambridge, 2013); p. 23.
7. Helis, L., Toda, Y., Hara, T., Miyazaki, H., and Abe, F.: Effect of cobalt on the microstructure of tempered martensitic 9Cr steel for ultra-supercritical power plants. Mater. Sci. Eng., A 510–511, 8894 (2009).
8. Verma, P., Rao, G.S., Chellapandi, P., Mahobia, G., Chattopadhyay, K., Srinivas, N.S., and Singh, V.: Dynamic strain ageing, deformation, and fracture behavior of modified 9Cr–1Mo steel. Mater. Sci. Eng., A 621, 39 (2015).
9. Abe, F., Horiuchi, T., Taneike, M., and Sawada, K.: Stabilization of martensitic microstructure in advanced 9Cr steel during creep at high temperature. Mater. Sci. Eng., A 378(1–2), 299 (2004).
10. Gupta, C., Dey, G.K., Chakravartty, J.K., Srivastav, D., and Banerjee, S.: A study of bainite transformation in a new CrMoV steel under continuous cooling conditions. Scr. Mater. 53(5), 559 (2005).
11. McDonald, E.J., Hallam, K.R., Bell, W., and Flewitt, P.E.J.: Residual stresses in a multi-pass CrMoV low alloy ferritic steel repair weld. Mater. Sci. Eng., A 325(1–2), 454 (2002).
12. Meng, D., Lu, F., Cui, H., Ding, Y., Tang, X., and Huo, X.: Investigation on creep behavior of welded joint of advanced 9% Cr steels. J. Mater. Res. 30(2), 197 (2015).
13. Lu, F., Liu, X., Wang, P., Wu, Q., Cui, H., and Huo, X.: Microstructural characterization and wide temperature range mechanical properties of NiCrMoV steel welded joint with heavy section. J. Mater. Res. 30(13), 2108 (2015).
14. Liu, W., Liu, X., Lu, F., Tang, X., Cui, H., and Gao, Y.: Creep behavior and microstructure evaluation of welded joint in dissimilar modified 9Cr–1Mo steels. Mater. Sci. Eng., A 644, 337 (2015).
15. El-Banna, E.M., Nageda, M.S., and Abo El-Saadat, M.M.: Study of restoration by welding of pearlitic ductile cast iron. Mater. Lett. 42(5), 311 (2000).
16. Furuya, H., Aihara, S., and Morita, K.: A new proposal of HAZ toughness evaluation Method-Part 1: Haz toughness of structural steel in multilayer and single-layer weld joints. Weld. J. 86(1), 1 (2007).
17. Wu, Q., Lu, F., Cui, H., Liu, X., Wang, P., and Tang, X.: Role of butter layer in low-cycle fatigue behavior of modified 9Cr and CrMoV dissimilar rotor welded joint. Mater. Des. 59, 165 (2014).
18. Guo, Q., Lu, F., Liu, X., Yang, R., Cui, H., and Gao, Y.: Correlation of microstructure and fracture toughness of advanced 9Cr/CrMoV dissimilarly welded joint. Mater. Sci. Eng., A 638(0), 240 (2015).
19. Guo, Q., Lu, F., Cui, H., Yang, R., Liu, X., and Tang, X.: Modelling the crack propagation behavior in 9Cr/CrMoV welds. J. Mater. Process. Technol. 226, 125 (2015).
20. Taneike, M., Sawada, K., and Abe, F.: Effect of carbon concentration on precipitation behavior of M23C6 carbides and MX carbonitrides in martensitic 9Cr steel during heat treatment. Metall. Mater. Trans. A 35, 1255 (2004).
21. Wu, Q., Lu, F., Cui, H., Liu, X., Wang, P., and Gao, Y.: Soft zone formation by carbon migration and its effect on the high-cycle fatigue in 9% Cr–CrMoV dissimilar welded joint. Mater. Lett. 141, 242 (2015).
22. Zhu, M.L. and Xuan, F.Z.: Effects of temperature on tensile and impact behavior of dissimilar welds of rotor steels. Mater. Des. 31, 3346 (2010).
23. Shekhter, A., Kim, S., Carr, D.G., Croker, A.B.L., and Ringer, S.P.: Assessment of temper embrittlement in an ex-service 1Cr–1Mo–0.25V power generating rotor by Charpy V-Notch testing, K Ic fracture toughness and small punch test. Int. J. Pressure Vessels Piping 79(8–10), 611 (2002).
24. Tanguy, B., Besson, J., Piques, R., and Pineau, A.: Ductile to brittle transition of an A508 steel characterized by Charpy impact test: Part I: Experimental results. Eng. Fract. Mech. 72(1), 49 (2005).
25. Haušild, P., Berdin, C., and Bompard, P.: Prediction of cleavage fracture for a low-alloy steel in the ductile-to-brittle transition temperature range. Mater. Sci. Eng., A 391(1–2), 188 (2005).
26. Song, S.H., Zhuang, H., Wu, J., Weng, L.Q., Yuan, Z.X., and Xi, T.H.: Dependence of ductile-to-brittle transition temperature on phosphorus grain boundary segregation for a 2.25Cr1Mo steel. Mater. Sci. Eng., A 486(1–2), 433 (2008).
27. Jeong, H., Nahm, S-H., Jhang, K-Y., and Nam, Y-H.: Evaluation of fracture toughness degradation of CrMoV rotor steels based on ultrasonic nonlinearity measurements. KSME Int. J. 16(2), 147 (2002).
28. Foulds, J. and Viswanathan, R.: Determination of the toughness of in-service steam turbine disks using small punch testing. J. Mater. Eng. Perform. 10(5), 614 (2001).
29. Chao, Y.J., Ward, J.D. Jr., and Sands, R.G.: Charpy impact energy, fracture toughness and ductile–brittle transition temperature of dual-phase 590 Steel. Mater. Des. 28(2), 551 (2007).
30. Kim, J.W., Lee, K., Kim, J.S., and Byun, T.S.: Local mechanical properties of alloy 82/182 dissimilar weld joint between SA508 Gr.1a and F316 SS at RT and 320 °C. J. Nucl. Mater. 384(3), 212 (2009).
31. Eghlimi, A., Shamanian, M., Eskandarian, M., Zabolian, A., and Szpunar, J.A.: Characterization of microstructure and texture across dissimilar super duplex/austenitic stainless steel weldment joint by austenitic filler metal. Mater. Charact. 106, 208 (2015).
32. Lundin, C., Khan, K., and Yang, D.: Report No. 1: Effect of carbon migration in Cr-Mo weldments on metallurgical structure and mechanical properties (Bulletin-Welding Research Council, 1995).
33. Celik, A. and Alsaran, A.: Mechanical and structural properties of similar and dissimilar steel joints. Mater. Charact. 43(5), 311 (1999).
34. Salemi, A. and Abdollah-Zadeh, A.: The effect of tempering temperature on the mechanical properties and fracture morphology of a NiCrMoV steel. Mater. Charact. 59(4), 484 (2008).
35. Zhu, M.L., Wang, D.Q., and Xuan, F.Z.: Effect of long-term aging on microstructure and local behavior in the heat-affected zone of a Ni–Cr–Mo–V steel welded joint. Mater. Charact. 87, 45 (2014).
36. Eghlimi, A., Shamanian, M., Eskandarian, M., Zabolian, A., and Szpunar, J.A.: Characterization of microstructure and texture across dissimilar super duplex/austenitic stainless steel weldment joint by super duplex filler metal. Mater. Charact. 106, 207 (2015).
37. Sattari-Far, I. and Farahani, M.R.: Effect of the weld groove shape and pass number on residual stresses in butt-welded pipes. Int. J. Pressure Vessels Piping 86, 723 (2009).
38. Lan, L., Qiu, C., Zhao, D., Gao, X., and Du, L.: Microstructural characteristics and toughness of the simulated coarse grained heat affected zone of high strength low carbon bainitic steel. Mater. Sci. Eng., A 529, 192 (2011).
39. Chen, T.H. and Yang, J.R.: Microstructural characterization of simulated heat affected zone in a nitrogen-containing 2205 duplex stainless steel. Mater. Sci. Eng., A 338, 166 (2002).
40. Lambert-Perlade, A., Gourgues, A.F., and Pineau, A.: Austenite to bainite phase transformation in the heat-affected zone of a high strength low alloy steel. Acta Metall. 52, 2337 (2004).
41. Francis, J.A., Mazur, W., and Bhadeshia, H.: Review type IV cracking in ferritic power plant steels. Mater. Sci. Technol. 22(12), 1387 (2006).
42. Liu, W., Liu, X., and Lu, F.: Creep behavior and microstructure evaluation of welded joint in dissimilar modified 9Cr–1Mo steels. Mater. Sci. Eng., A 644, 337 (2015).
43. Huang, M. and Wang, d.L.: Carbon migration in 5Cr–0.5Mo/21Cr–12Ni dissimilar metal welds. Metall. Mater. Trans. A 29(12), 3037 (1998).
44. You, Y.Y., Shiue, R.K., Shiue, R.H., and Chen, C.: The study of carbon migration in dissimilar welding of the modified 9Cr–1Mo steel. J. Mater. Sci. Lett. 20(15), 1429 (2001).
45. Cao, R., Feng, W., Peng, Y., Du, W.S., Tian, Z.L., and Chen, J.H.: Investigation of abnormal high impact toughness in simulated welding CGHAZ of a 8% Ni 980 MPa high strength steel. Mater. Sci. Eng., A 528(2), 631 (2010).
46. Arioka, K., Yamada, T., Terachi, T., and Chiba, G.: Influence of carbide precipitation and rolling direction on intergranular stress corrosion cracking of austenitic stainless steels in hydrogenated high-temperature water. Corrosion 62(7), 568 (2006).
47. Petch, N.J.: The influence of grain boundary carbide and grain size on the cleavage strength and impact transition temperature of steel. Acta Metall. 34(7), 1387 (1986).
48. Islam, M.A.: Grain boundary segregation behavior in 2.25Cr–1Mo steel during reversible temper embrittlement. J. Mater. Eng. Perform. 16(1), 73 (2007).



Full text views

Total number of HTML views: 0
Total number of PDF views: 0 *
Loading metrics...

Abstract views

Total abstract views: 0 *
Loading metrics...

* Views captured on Cambridge Core between <date>. This data will be updated every 24 hours.

Usage data cannot currently be displayed