For a steel alloy it has been determined that a carburizing heat treatment of 18 h duration at 891°C will raise the carb

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For a steel alloy it has been determined that a carburizing heattreatment of 18 h duration at 891°C will raise thecarbon concentration to 0.49 wt% at apoint 2.7 mm from the surface. Estimate the timenecessary to achieve the same concentration at a 5.4 mmposition for an identical steel and at a carburizing temperatureof 1140°C. Assumethat D0 is 3.1 ×10-4 m2/sand Qd is 108 kJ/mol.