Question

BCC Specimen

Material: transformer iron

Calculate grain size by intercept method using the data below

(Me) eye piece magnification: 10

(Mo) objective magnification: 50

Scan # # of grains apparent length of scan

1 3 1cm

2 3 1cm

3 4 1cm

4 4 1cm

5 5 1cm

___________________________________________________________

Total: G= 19 L=5cm(Me)= _____________

· Actual grain intercept distance= (L)/(G*(Me)*(Mo)) = ______________________

· Grain size(from ASTM standard E112) =_____________________________

· Assuming equiaxed grains calculate the number of grains in 1m^3 of this sample (note:P(iron)=7.88 g/(cm^3) – this information may be useful)

MICRO-GRAIN SIZE RELATIONSHIPS From ASTM Standard E112A ASTM Calculated Average Calculated Area of Average Nominal Nominal "Diameter" of Average Grain umber of Grains Micro Intercept Grains Grains per per mm 2 per inn2 mmA3 at 1 at 100X Grain Average Grain Distance Section Size Number mm mmn2 x10-3. 10-3 x10-2 x10-5 508 20.000 0.451 17.80 258 400 7.63 3.88 0.25 0.359 7.090 0.319 12.60 29 200 21.6 7.75 0.5 0.5 0.302 7.070 0.268 10.60 11 0.707 91.2 14 36.3 1.0 0.254 5.950 0.226 8.88 64.5 100 61 15.5 0.25 9.840 0.222 8.74 62.5 96.9 64 16 1.03 0.214 8.410 1.5 0.19 7.47 45.6 70.7 103 21.9 1.41 0.2 7.870 0.178 6.99 40 62 125 25 1.61 0.18 7.090 0.16 6.29 32.4 50.2 30.9 1.99 172.3 2.0 0.18 7.070 0.16 6.28 32.3 50 31 2.5 0.151 5.950 0.134 5.30 22.8 35.4 290 43.8 2.83 0.15 5.910 0.133 5.24 22.5 34.9 296 44.4 2.87 0.127 5.000 3.0 0.113 4.44 16.1 25 488 62 0.12 4.720 0.107 4.20 0.0948 3.73 0.0799 3.15 14.4 22.3 578.9 69.4 4.48 3.5 0.107 4.200 11.4 17.7 821 87.7 5.66 0.09 3.540 8.1 12.6 1370 123 7.97 4.0 0.0898 3.540 0.0797 3.14 8.06 12.5 1380 124 4.5 0.076 2.970 0.0671 2.64 5.7 8.84 2320 175 11.3 0.07 2.760 0.0622 2.45 4.9 7.59 2920 204 13.2 5.0 0.064 2.50 0.0564 2.22 4.03 6.25 3910 248 16 0.06 2.360 0.0533 2.10 3.6 5.58 4630 278 17.9 0.0534 2.100 0.0474 1.8 5.5 351 22.6 400 25.8 6.0 0.045 1.770 0.0399 1.57 496 32