Improvement in Properties of 301LN Austenitic Stainless Steel for Metro Coach Manufacture

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Abstract:

Metastable austenitic stainless steel type 301LN is widely used for fabrication of structural components of Metro Coaches. The steel exhibits both high strength and enhanced plasticity due to strain hardening as well as formation of strain-induced martensite (α) during cold deformation (TRIP effect). The current market requirement, as projected by many of the ongoing Metro Rail Projects in India, calls for manufacture of this steel with ultimate tensile strength (UTS) in excess of 1000 MPa and yield (YS/UTS) ratio of less than 0.8, as this would facilitate substantial reductions in tare weight and crash-worthiness of metro coaches. The typical property requirements in high temper (HT) as per one typical Metro Coach specification are: Yield Strength (YS) ~ 751-921 MPa, Ultimate Tensile Strength (UTS) ~ 1001-1151 MPa, Elongation ~ 22% min, Hardness ~ 36 HRC max and YS/UTS ratio <0.8. previous="" plant="" experience="" has="" shown="" that="" the="" maximum="" attainable="" uts="" in="" this="" grade="" through="" cold="" rolling="" is="" only="" to="" tune="" of="" 970="" mpa="" and="" any="" excess="" deformation="" severely="" impairs="" both="" ductility="" 22="" hardness=""> 36 HRC) beyond acceptable limits. In the present work, an innovative thermomechanical processing (TMP) methodology has been evolved for the attainment of this seemingly unlikely combination of properties through experimental cold rolling and short annealing simulations in Gleeble 3500 C thermomechanical simulator. The novel process methodology entails imparting heavy cold reductions (CR) of 45-50% in Sendzimir Mill followed by brief/ short reversion annealing treatments (80-160 s) by means of single furnace operation at 750 °C at standard line operating speeds for 300 series in Annealing Pickling Line-1 (AP Line-1) of Salem Steel Plant (SSP) in India. The improvement in properties (strength-ductility combination) has been attributed to grain refinement through formation of submicron grained austenitic (γ) microstructure by controlled reversion of strain-induced martensite (α) during the short annealing treatment. The process is distinct from conventional long annealing treatments (300-360 s), which are employed to soften the steel after cold rolling by means of recovery and recrystallization processes.

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September 2013

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[1] L.P. Karjalainen, T. Taulavuori, M. Sellman, A. Kyröläinen, ome Strengthening Methods for Austenitic Stainless Steels, Steel Res. Int., 79 (2008) 404-412.

DOI: 10.1002/srin.200806146

Google Scholar

[2] M.C. Somani, P. Juntunen, L.P. Karjalainen, R.D.K. Misra, A. Kyröläinen, Enhanced Mechanical Properties through Reversion in Metastable Austenitic Stainless Steels, Metall. Mater. Trans. A, 40a, (2009) 729-744.

DOI: 10.1007/s11661-008-9723-y

Google Scholar

[3] M. Eskandari, A. Najafizadeh, A. Kermanpur, M. Karimi, Potential application of nanocrystalline 301 austenitic stainless steel in lightweight vehicle structures, Mater. Des. 30 (2009) 3869-3872.

DOI: 10.1016/j.matdes.2009.03.043

Google Scholar

[4] A. Rezaee, A. Najafizadeh, A. Kermanpur, M. Moallemi, The influence of reversion annealing behavior on the formation of nanograined structure in AISI 201L austenitic stainless steel through martensite treatment, Mater. Des. 32 (2011) 4437-4442.

DOI: 10.1016/j.matdes.2011.03.065

Google Scholar

[5] T. Maki, Stainless steel: progress in thermomechanical treatment, Curr. Opin. Solid State Mater. Sci., 2 (1997) 290-295.

Google Scholar

[6] A.D. Manshadi, M.R. Barnett, P.D. Hodgson, Recrystallization in AISI 304 austenitic stainless steel during and after hot deformation, Mater. Sci. Eng. A, 485 (2008) 664-762.

DOI: 10.1016/j.msea.2007.08.026

Google Scholar

[7] S. Rajasekhara, L. P. Karjalainen, A. Kyröläinen, P. J. Ferreira, Microstructure evolution in nano/submicron grained AISI 301LN stainless steel, Mater. Sci. Eng. A, 527 (2010) 1986–(1996).

DOI: 10.1016/j.msea.2009.11.037

Google Scholar

[8] M. Moallemi, A. Najafizadeh, A. Kermanpur, A. Rezaee, Effect of reversion annealing on the formation of nano/ultrafine grained structure in 201 austenitic stainless steel, Mater. Sci. Eng. A, 530 (2011) 378-381.

DOI: 10.1016/j.msea.2011.09.099

Google Scholar

[9] A.A. Lebedev and V.V. Kosarchuk, Influence of phase transformations on the mechanical properties of austenitic stainless steels, Int. J. of Plast., 16 (2000) 749-767.

DOI: 10.1016/s0749-6419(99)00085-6

Google Scholar

[10] K. Tomimura, S. Takaki, Y. Tokunaga, Reversion Mechanism from Deformation Induced Martensite to Austenite in Metastable Austenitic Stainless Steels, ISIJ Int., 31 (1991) 1431-1437.

DOI: 10.2355/isijinternational.31.1431

Google Scholar

[11] K. Tomimura, S. Takaki, S. Tanimoto, Y. Tokunaga, Optimal Chemical Composition in Fe-Cr-Ni Alloys for Ultra Grain Refining by Reversion from Deformation Induced Martensite, ISIJ Int., 31 (1991) 721-727.

DOI: 10.2355/isijinternational.31.721

Google Scholar

[12] R.D.K. Misra, S. Nayak, S.A. Mali, J.S. Shah, M.C. Somani, L.P. Karjalainen, On the Significance of Nature of Strain-Induced Martensite on Phase-Reversion-Induced Nanograined/Ultrafine-Grained Austenitic Stainless Steel, Metall. Mater. Trans. A, 41 (2010).

DOI: 10.1007/s11661-009-0072-2

Google Scholar

[13] R.D.K. Misra, S. Nayak, S.A. Mali, J.S. Shah, M.C. Somani, L.P. Karjalainen, Microstructure and Deformation Behavior of Phase-Reversion-Induced Nanograined/Ultrafine-Grained Austenitic Stainless Steel, Metall. Mater. Trans. A, 40 (2009).

DOI: 10.1007/s11661-009-9920-3

Google Scholar

[14] J. Talonen, P. Nenonen, G. Pape, H. Hänninen, High-strength steel development for pipelines: A brazilian perspective, Metall. Mater. Trans. A, 36 (2005) 423-454.

Google Scholar

[15] A. Rezaee, A. Kermanpur, A. Najafizadeh, M. Moallemi, Production of nano/ultrafine grained AISI 201L stainless steel through advanced thermo-mechanical treatment, Mater. Sci. Eng. A, 528 (2011) 5025-5029.

DOI: 10.1016/j.msea.2011.02.093

Google Scholar

[16] B. Ravi Kumar, Sailaja Sharma, B. Mahato, Formation of ultrafine grained microstructure in the austenitic stainless steel and its impact on tensile properties, Mater. Sci. Eng. A, 528 (2011) 2209-2216.

DOI: 10.1016/j.msea.2010.11.034

Google Scholar

[17] J. Talonen, H. Hanninen, Formation of shear bands and strain-induced martensite during plastic deformation of metastable austenitic stainless steels, Acta. Mater., 55 (2007) 6108-6118.

DOI: 10.1016/j.actamat.2007.07.015

Google Scholar

[18] K. Nohara, Y. Ono, N. Ohashi, Composition and grain-size dependencies of strain-induced martensitic transformation in metastable austenitic stainless steels, ISIJ Int, 63 (1977) 212-222.

DOI: 10.2355/tetsutohagane1955.63.5_772

Google Scholar

[19] V. Shrinivas, S.K. Varma, L. Murr, Deformation-induced martensitic characteristics in 304 and 316 stainless steels during room-temperature rolling, Metall. Trans. A, 26 (1995) 661-671.

DOI: 10.1007/bf02663916

Google Scholar

[20] T. Angel, Formation of martensite in austenitic stainless steels: effects of deformation, temperature, and composition, Iron Steel Inst, 177 (1954) 165-174.

Google Scholar

[21] M. Shimojo, T. Inamura, T.H. Myeong, K. Takashima, Formation of nanosized martensite particles in stainless steels, Metall. Trans. A, 32 (2001) 261-265.

DOI: 10.1007/s11661-001-0257-9

Google Scholar

[22] H. Mirzadeh, A. Najafizadeh, Correlation between processing parameters and strain-induced martensitic transformation in cold worked AISI 301 stainless steel, Mater. Charac., 59 (2008) 1650-1654.

DOI: 10.1016/j.matchar.2008.03.004

Google Scholar