The Iron and steel magazine . 702 710 700 708 716 719 692 710 Curve number 1 2 3 4 5 6 7 8 The variations lie outside of the possible errors in the meas-urement of the temperature; since, however, slight differencein the rapidity of cooling plainly alters the location of this point,the difference shown here might perhaps be traceable to suchchanges in the rapidity of cooling. 200 The Iron and Steel Magazine It is now a pleasant task to support or extend the knowl-edge gained from the thermal investigation of the material byan independent method. The microscope is an indispensableaid in the stu
The Iron and steel magazine . 702 710 700 708 716 719 692 710 Curve number 1 2 3 4 5 6 7 8 The variations lie outside of the possible errors in the meas-urement of the temperature; since, however, slight differencein the rapidity of cooling plainly alters the location of this point,the difference shown here might perhaps be traceable to suchchanges in the rapidity of cooling. 200 The Iron and Steel Magazine It is now a pleasant task to support or extend the knowl-edge gained from the thermal investigation of the material byan independent method. The microscope is an indispensableaid in the study of metals and alloys and could give more valu-able information still if it were possible to observe the structureof a cross section at any temperature; since, however, the tem-peratures here considered forbid an actual use of the microscope,we must retard the structure peculiar to a mass of metal at ahigher temperature and examine it at the ordinary shall then surely produce an unstable condition and a ten-. Fig. 17. Magnified 50 diameters dency will always be at work to gradually restore the suppressedchange. Let us next observe slowly cooled materials. These couldpass completely through both the changes at 11350 C. and thoseat 7000 C. Cast iron free from graphite will thus contain freecarbide as cementite and pearlite, the normal union of carbideand iron. Photograph 12 shows such an iron magnified 50diameters. It consists of white fields which are dotted withnumerous dark spots. Magnified still more (photograph 13)the latter prove to be a number of fine laminations which showthe characteristic structure of the mixture, the pearlite. The 11 on ( (ii hoi . [Hoys 20I cementite is extremely hard and is not attacked by dilute acid . 11 a polished piece of such iron is treated with dilute acid, thecementite remains unattacked in relief while the separate ferriteplates of the pearlite between the cementite laminations areeaten away. In this way the pearlite plates
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Keywords: ., bookcentury1800, bookdecade1890, bookidironsteel, booksubjectiron
