Figure 7a. Frequency of UTS for Chill #1 Condition.


Figure 7b. Frequency of UTS for Chill #2 Condition.


For the fourth iteration, which uses the Chill #2 design, the test bar will remain in position #2 as it still produces a more refined microstructure in the chilled casting section as shown in Figure 1. The YS still remains close to the values seen with Chill #1, but both plastic elongation and UTS rise significantly due to the further reduction of both λ2


and po-


rosity. The fifth and sixth iteration are repeated in terms of the casting chill and melt conditions encountered in iteration #4, except that sample blank extraction was performed by Lab #1 and Computer Numerically Controlled (CNC) lath preparation of the tensile bars was performed by Lab #2. Lab


40


#2 performed tensile testing on 30 samples (iteration #5), shipping the remainder balance of 30 (iteration #6) to Lab #2 for tensile testing. The purpose of iterations 4 to 6 was to generate data from a blind inter-laboratory testing regime to support Proficiency Testing requirements as agreed between both Labs and A2LA. From Table 4, the expected agreement in YS values is found, and a slight variation exists (±σ still overlaps) in the UTS and the plastic elongation values. How- ever, the true degree of scatter is not specifically known with the use of a standard deviation. The use of the Weibull plots was employed to specifically assess repeatability.


International Journal of Metalcasting/Winter 10


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