View More View Less
  • 1 Institute of Metals and Technology, Lepi pot 11, 1000, Ljubljana, Slovenia
  • | 2 Faculty of Natural Sciences and Engineering, University of Ljubljana, Aškerčeva 12, 1000, Ljubljana, Slovenia
  • | 3 Acroni d.o.o., Cesta Borisa Kidriča 44, 4270, Jesenice, Slovenia
Restricted access

Abstract

The solidification sequence of austenitic stainless steels can be predicted with thermodynamic calculations. Another way is to use models where the value of the Creq./Nieq. ratio determines the relationship between the solidification mode and the composition factor. In this study the solidification of AISI 304LN stainless steel at different cooling rates was studied using differential scanning calorimetry (DSC). The samples were linearly heated above the liquidus temperature to 1550 °C at heating rates of 5, 10, and 25 K/min. The solidification (cooling) scans from 1550 °C involved the same selected ramps. After the DSC measurements the samples were metallographically analyzed to reveal the variations in the solidification microstructures. The microhardness of the solidified samples was also measured. It was found that the cooling rate critically influenced the solidification. The solidification behavior, which depends on the cooling rate, determines the evolution of the microstructure. At the slowest cooling rates a relief-cell morphology was observed, and at the fastest cooling rate the formation of dendrites was evident. With an increasing cooling rate the liquidus temperature decreased and the reaction enthalpy increased.

  • 1. Bhadeshia, HKDH, Honeycombe, RWK. Steels. 3 Amsterdam: Elsevier; 2007 270.

  • 2. Torkar, M, Mandrino, Dj, Lamut, M. An AES investigation of brushed AISI 304 stainless steel after corrosion testing. Materiali in tehnologije. 2008;42:3943.

    • Search Google Scholar
    • Export Citation
  • 3. Kulkarni, S, McCowan, CN, Olson, DL. Improvement of weld characteristics by variation in welding processes and parameters in joining of thick wall 304LN stainless steel pipe. ISIJ Int. 2008;48:15601569. .

    • Crossref
    • Search Google Scholar
    • Export Citation
  • 4. Rajasekhar, K, Harendranath, CS, Raman, R, Kulkarni, SD. Microstructural evolution during solidification of austenitic stainless steel weld metals: a color metallographic and electron microprobe analysis study. Mater Charact. 1997;38:5365. .

    • Crossref
    • Search Google Scholar
    • Export Citation
  • 5. Nassar, H, Korojy, B, Fredriksson, H. A study of shell growth irregularities in continuously cast 310S stainless steel. Ironmaking Steelmaking. 2009;36:521528. .

    • Crossref
    • Search Google Scholar
    • Export Citation
  • 6. Shankar V , Gill TPS, Mannan SL, Sundaresan S. Solidification cracking in austenitic stainless steel welds. In: Raj B, Rao KBS, editors. Frontiers in materials science. Bangalore: Universities Press; 2005. p. 35982.

    • Search Google Scholar
    • Export Citation
  • 7. Lee, DJ, Byun, JC, Sung, JH, Lee, HW. The dependence of crack properties on thr Cr/Ni equivalent ratio in AISI 304L austenitic stainless steel weld metals. Mater Sci Eng A. 2009;513–4:154159.

    • Search Google Scholar
    • Export Citation
  • 8. Huang, FX, Wang, XH, Zhang, JM, et al. In situ observation of solidification process of AISI 304 austenitic stainless steel. J Iron Steel Res Int. 2008;6:7882. .

    • Crossref
    • Search Google Scholar
    • Export Citation
  • 9. Tehovnik, F, Arzenšek, B, Arh, B. Tensile tests on stainless steels in temperature range 800 to 1200 °C. Metalurgija. 2008;47:7579.

    • Search Google Scholar
    • Export Citation
  • 10. Tehovnik, F, Vodopivec, F, Arzenšek, B, Celin, R. The effect of lead on the hot workability of austenitic stainless steel with a solidification structure. Metalurgija. 2010;49:4952.

    • Search Google Scholar
    • Export Citation
  • 11. Davis JR . Stainless steels. Materials Park: ASM International; 1999. p. 370.

  • 12. Dioszegi, A, Svensson, IL. On the problems of thermal analysis of solidification. Mater Sci Eng A. 2005;413–4:474479.

  • 13. Naglič, I, Smolej, A, Doberšek, M, Mrvar, P. The influence of TiB2 particles on the effectiveness of Al-3Ti-0.15C grain refiner. Mater Charact. 2008;59:14581465. .

    • Crossref
    • Search Google Scholar
    • Export Citation
  • 14. Arockiasamy, A, German, RM, Wang, P, Horstemeyer, MF, Suri, P, Park, SJ. DSC analysis of Al6061 aluminium alloy powder by rapid solidification. J Therm Anal Calorim. 2010;100:361366. .

    • Crossref
    • Search Google Scholar
    • Export Citation
  • 15. Gazda, A. Analysis of decomposition processes of ausferrite in copper-nickel austempered ductile iron. J Therm Anal Calorim. 2010;102:923930. .

    • Crossref
    • Search Google Scholar
    • Export Citation
  • 16. Schaeffler, AL. Constitution diagram for stainless steel weld metal. Met Prog. 1949;56:680.

  • 17. Koseki, T, Inoue, H, Morimoto, H, Ohkita, S. Prediction of solidification and phase transformation of stainless steel weld metals. Nippon Steel Tech Rep. 1995;65:3340.

    • Search Google Scholar
    • Export Citation
  • 18. Pohar, C, Klinar, M, Kosmač, A. Correlation of the occurrence of surface cracks on stainless-steel heavy plates with ferrite numbers and crack indexes. Materiali in tehnologije. 2004;38:185190.

    • Search Google Scholar
    • Export Citation
  • 19. Liang, GF, Wan, CQ, Wu, JC, Zhu, GM, Yu, Y, Fang, Y. In-situ observation of growth behaviour and morphology of delta-ferrite as function of solidification rate in an AISI304 stainless steel. Acta Metall Sin. 2006;19:441448.

    • Search Google Scholar
    • Export Citation