Communication Density of Liquid Fe-Mn-C Alloys LE THU HOAI and JOONHO LEE The density of liquid Fe-Mn-C alloys was determined at temperatures ranging from 1687 K to 1834 K (1414 C to 1561 C) by using the advanced sessile drop method. Regression analysis of the experimental data produced the following description of the density of the Fe-Mn-C alloys:   qFeMnC g=cm3   ¼ 7:10  2:2  WFM þ 0:60  WFM2 ð0:129 þ 0:67  WFMÞ  ½wt pct C o   þ 1:45  102 þ 7:6  102  WFM  ½wt pct C2     1:83  103  4:11  105 þ 1:7  106  WFM ½wt pct Cg  ðT  1823Þ where WFM ¼

½wt pct Mn ½wt pct Mn þ ½wt pct Fe

DOI: 10.1007/s11663-011-9555-9  The Minerals, Metals & Materials Society and ASM International 2011

dependence of liquid Fe-Mn alloys at 1823 K (1550 C) can be described by Eq. [1].   qFeMn g=cm3 ¼ 7:10  2:2  102 ½wt pct Mn þ 6:0  105 ½wt pct Mn2

High Mn alloys generally contain Al, Si, and C. Therefore, the density data for Fe-Mn-X (X = Al, Si, C) are required for process optimization. In this study, the effect of carbon addition on the density of liquid Mn-Al alloys was examined at temperatures ranging from 1687 K to 1834 K (1414 C to 1561 C) with the advanced sessile drop method. Experimental details were described in our previous study.[1] We examined two different carbon alloys by fixing the weight fractions of Mn (WFM = [wt pct Mn]/{[wt pct Mn] + [wt pct Fe]} = 0.05 and 0.10). There is no theoretical model to describe the density of the alloys containing interstitial elements such as carbon.[3] Therefore, the density of Fe-Mn-C alloys was determined by the regression method. Figure 2 shows the temperature dependence of the density of the Fe-Mn-C alloys for WFM = 0.05, in comparison with the density of Fe-Mn alloys. The present measurements were carried out for a wider temperature range than the previous ones, and they showed similar linear temperature dependences. Figure 3 shows the temperature dependence of the density of the Fe-Mn-C alloys for WFM = 0.10. The experimental results also showed linear temperature dependences. In this study, 1823 K (1550 C) was taken as a reference temperature. Therefore, the density of each Fe-Mn-C alloy can be described by Eq. [2]:   qFeMnC g=cm3 ¼ qFeMnC þ K  ðT  1823Þ

Recently, much attention has been paid to high manganese steels (HMnS) that exhibit an excellent combination of strength and ductility as a result of the competition between different plasticity mechanisms. However, in terms of processing, the problems of refining and casting encountered in many new HMnS have limited the commercialization of such alloys. To optimize the refining and casting process, the thermophysical properties of liquid alloy are essential. However, unlike conventional alloys, only limited information is available for HMnS. Density is very fundamental information for controlling the refining and casting processes. Recently, we measured the density of liquid Fe-Mn alloys by using the advanced sessile drop method.[1] The density data in our previous study showed reasonable accordance with the data of Popel et al.[2] (Figure 1). The concentration

LE THU HOAI, Graduate Student, and JOONHO LEE, Associate Professor, are with the Department of Materials Science and Engineering, Korea University, Seoul 136-713, South Korea. Contact e-mail: [email protected] Manuscript submitted May 10, 2011. Article published online July 28, 2011. METALLURGICAL AND MATERIALS TRANSACTIONS B

½1

½2

where qFeMnC is the density of the Fe-Mn-C alloy at 1823 K (1550 C), T the temperature (K), and L the temperature coefficient (g/cm3 K). Figure 4 shows the carbon concentration dependence of the density of the liquid Fe-Mn-C alloys at 1823 K (1550 C). Jimbo and Cramb reported that the density of Fe-C alloy decreased linearly with increasing carbon content.[3] However, careful inspection of the experimental results revealed that the decrease in density of the Fe-Mn-C alloys from 0 to 2 wt pct C was greater than that from 2 to 4 wt pct C. The same behavior was also observed in the present results. Consequently, a second-order polynomial equation was derived at each WFM (0.00, 0.05, and 0.10). Figure 5 shows the negative temperature coefficients of the two alloys examined. The difference in the temperature coefficient increased by increasing the carbon content. The current negative temperature coefficient (1.59~1.83 9 103) was higher than that of Fe-C reported by Jimbo and Cramb (5.36~8.28 9 104). However, considering the large scatter in the previous data (4.6 9 104~1.6 9 103) of the Fe-C alloy,[4–8] the current results are acceptable. Consequently, based on these results, the density of Fe-Mn-C alloys can be described by Eqs. [3] and [4]. VOLUME 42B, OCTOBER 2011—925

Fig. 1—Density of the liquid Fe-Mn alloys at 1823 K (1550 C).

Fig. 2—Temperature dependence of density of the liquid Fe-Mn-C alloys for [wt pct Mn]/{[wt pct Mn] + [wt pct Fe]} = 0.05.

Fig. 4—Carbon concentration dependence of density of the liquid Fe-Mn-C alloys at 1823 K (1550 C).

Fig. 5—Temperature coefficient of density of the liquid Fe-Mn-C alloys.

  qFeMnC g=cm3   ¼ f 7:10  2:2  WFM þ 0:60  WFM2 : ð0:129 þ 0:67  WFMÞ  ½wt pct C   þ 1:45  102 þ 7:6  102  WFM  ½wt pct C2 g    f1:83  103  4:11  105 þ 1:7  106  WFM  ½wt pct Cg  ðT  1823Þ

WFM ¼

Fig. 3—Temperature dependence of density of the liquid Fe-Mn-C alloys for [wt pct Mn]/{[wt pct Mn] + [wt pct Fe]} = 0.10. 926—VOLUME 42B, OCTOBER 2011

½wt pct Mn ½wt pct Mn þ ½wt pct Fe

½3

½4

This work was supported by the Industrial Strategy Technology Development (No. 10033508, High METALLURGICAL AND MATERIALS TRANSACTIONS B

Functional Alloy Metal) through a grant provided by the Ministry of Knowledge Economy, Korea.

REFERENCES 1. J. Lee, L.T. Hoai, and M. Shin: Metall. Mater. Trans. B, 2011, vol. 42B, pp. 546–49. 2. S.I. Popel, B.V. Tsarevskiy, and N.K. Dzhemilev: Phys. Met. Metallogr, 1964, vol. 18 (3), pp. 158–60.

METALLURGICAL AND MATERIALS TRANSACTIONS B

3. I. Jimbo and A.W. Cramb: Metall. Trans. B, 1993, vol. 24B, pp. 5– 10. 4. C. Benedicks, N. Ericsson, and G. Ericson: Arch. Eisenhuettenwes., 1930, vol. 3, pp. 473–86. 5. E. Widawski and F. Sauerwald: Z. Anorg. Allg. Chem., 1930, vol. 192, pp. 145–60. 6. L.D. Lucas: Mem. Sci. Rev. Metall., 1964, vol. 61, pp. 97–116. 7. A.A. Vertman, A.M. Samarin, and E.S. Filippov: Dolk. Akad. Nauk SSSR, 1964, vol. 155 (2), pp. 323–25. 8. S. Saito and Y. Sakuma: Proc. 63rd Meeting Jpn. Inst. Met., 1968, p. 268.

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