This page contains a Flash digital edition of a book.
2). This is only slightly higher than the critical velocity of 0.5 m/s recommended by other researchers and within the prediction errors of the simulation.13


The overall fluid flow


was relatively laminar, and a uniform filling profile was maintained as the casting filled. A close examination of the fluid flow within the in-gate at the peak velocity reveals a laminar flow with little recirculation and no indication of turbulent flow (See Figure 3).


The laminar fluid flow within the casting and low fluid veloci- ties would result in little reoxidation within the casting dur- ing filling. It would be possible for reoxidation products from ladle filling to enter the casting since no filter was utilized in the gating system; however, an unfiltered gating system had been intentionally employed so RE oxides that formed within the ladle during filling would not be removed. Removal of these oxides might completely prevent refinement.


Mechanical Testing


Figures 4 and 5 illustrate the yield strength (YS), ultimate tensile strength (UTS), and percent elongation (EL) for the 1010 tensile bars. No mechanical properties were reported for the 1010 heat with 0.1% misch metal and La2


tions. After pouring this casting four times, the author was unable to obtain a porosity free casting.


O3


similar between the baseline as-cast 1010 and all of the RE samples except the 1010 with 0.1% misch metal addition, which was lower. Elongation for some of the tensile bars was significantly higher than the baseline as-cast 1010. The best elongations were for the samples containing 0.2% misch metal addition and with 0.1% rare earth silicide and La2


O3 0.1% rare earth silicide and La2 O3


had an elongation around 38% while the other two had an elongation of 8%. This large difference in tensile bar elon- gation is surprising. The same set of tensile bars had very similar yield strengths.


addition. Of particular interest was the 1010 with O3


Figure 6 depicts the yield strength as a function of actual total rare earth content. At a total RE content of 0.007%, the yield strength of the bars was lower than the base- line as-cast 1010 material. Yield strength appears to peak around 0.04% and then gradually decline (Figure 6). How- ever, even at 0.12% total rare earth (TRE), the strength is higher than the baseline as-cast 1010. It should be noted, at a TRE above 0.8%, the samples with La2


fective when sufficient RE was in the melt. The excess RE may restrict grain growth and increase constitutional un-


ditions were stronger than the samples containing only a RE addition. It appears the La2


O3 O3 International Journal of Metalcasting/Spring 2012 powder ad- additions were only ef- Figure 5. Percent elongation of 1010 tensile bars. 55 , two of the tensile bars


The yield strength of most of the RE addition samples was higher than the as-cast 1010 material. The average yield strength of the baseline as-cast 1010 was 170 MPa; the average yield strength of the 1010 with 0.1% rare earth silicide and La2


addition was 195 MPa. The UTS was addi-


Figure 3. Velocity plot of the in-gate with velocity vectors depicting flow within the in-gate at 0.7943 seconds


Figure 4. Yield strength and ultimate tensile strength of the 1010 bars.


Page 1  |  Page 2  |  Page 3  |  Page 4  |  Page 5  |  Page 6  |  Page 7  |  Page 8  |  Page 9  |  Page 10  |  Page 11  |  Page 12  |  Page 13  |  Page 14  |  Page 15  |  Page 16  |  Page 17  |  Page 18  |  Page 19  |  Page 20  |  Page 21  |  Page 22  |  Page 23  |  Page 24  |  Page 25  |  Page 26  |  Page 27  |  Page 28  |  Page 29  |  Page 30  |  Page 31  |  Page 32  |  Page 33  |  Page 34  |  Page 35  |  Page 36  |  Page 37  |  Page 38  |  Page 39  |  Page 40  |  Page 41  |  Page 42  |  Page 43  |  Page 44  |  Page 45  |  Page 46  |  Page 47  |  Page 48  |  Page 49  |  Page 50  |  Page 51  |  Page 52  |  Page 53  |  Page 54  |  Page 55  |  Page 56  |  Page 57  |  Page 58  |  Page 59  |  Page 60  |  Page 61  |  Page 62  |  Page 63  |  Page 64  |  Page 65  |  Page 66  |  Page 67  |  Page 68  |  Page 69  |  Page 70  |  Page 71  |  Page 72  |  Page 73  |  Page 74  |  Page 75  |  Page 76  |  Page 77  |  Page 78  |  Page 79  |  Page 80  |  Page 81  |  Page 82  |  Page 83  |  Page 84  |  Page 85  |  Page 86  |  Page 87  |  Page 88  |  Page 89  |  Page 90  |  Page 91