MAKING AND WORKING OF WROUGHT IRON 399 



To illustrate: What pressure would be required for forcing a 

 9 in. diameter crank pin into a cast steel center? The pressure 

 required is expressed by the following formula, where P is pressure 

 and D diameter of pin. 



P = 15 D + 15 , 

 :.P = 15 X9 + 15 = 150 tons 



Questions 



1. What is wrought iron? 



2. How is it made? 



3. What are the physical properties of wrought iron? 



4. What effect has drawing and rolling on the metal? 



5. What is case-hardening? Why is it desirable? 



6. What is malleable cast iron? How is it made? 



7. Give the physical properties of each kind of iron. 



8. What is blacksmithing? 



9. Describe a forge. State how a high temperature is obtained. 



10. What is an anvil? How is an anvil made so as to resist 

 dents? 



11. Name some of the blacksmith's tools. Draw sketches and 

 show the mechanical principle of the sledge hammer and chisel. 



12. What is scarfing? 



13. What is welding? 



14. Explain the drop forging. 



15. What is a shrunk fit? 



16. What is a forced fit? Give the principle of science under- 

 lying it. 



17. What is autogeneous welding? 



18. What is electric arc welding? 



19. What is thermit welding? 



20. What is oxyacetylene welding? 



