英文科学读本 第二册·Lesson 27 Wrought Iron

Lesson 27 Wrought Iron

Teacher showed us some things made of wrought iron today, said Willie. "They are not at all like the cast-iron things we were talking about.

He had a strip of wrought iron. He beat it with a hammer. He bent it and twisted it about in all sorts of rough ways. But it did not break, because wrought iron is very tough and flexible.

Teacher showed us too, said Fred, "that wrought iron is malleable. It is not malleable when it is cold, like lead is. Iron must be made red-hot before it can be hammered out. When it is red-hot it becomes pliable, and can be hammered into any shape we please."

I have watched the blacksmith at the forge, said Norah. "He puts the iron into the furnace and makes it red-hot. Then he lays it on the anvil, and beats it with his hammer. The iron which he works must be wrought iron, I suppose, for it is malleable."

Teacher next showed us some iron wire, said Willie. "It could not be cast-iron, for cast-iron is not ductile. This iron had been drawn out into very fine wire, and it must be ductile."

I say, Norah, said Fred, "you know we went to the blacksmith's shop to get my iron hoop mended?"

Yes, said Norah. "I watched him put the broken ends of the hoop into the fire, and when they were red-hot he hammered them together."

Quite right, said Fred. "It is almost as easy to weld wrought iron together, when it is red-hot and pliable, as it is to join two pieces of clay or putty.

Wrought iron can be made into any kind of article with the help of the forge, hammer, and anvil. It is malleable, and can be beaten into any shape we please. It is ductile and tough, and can be drawn out into wire of any thickness. Its immense strength renders it just the thing for making girders, or beams for bridges, and arches, and great buildings. It is used for making steam engines, which have to do all sorts of work. Chains, too, of all kinds are made of wrought iron, because wrought iron will bear any amount of tugging and straining without giving way."

SUMMARY

Wrought iron is tough, flexible, malleable, and ductile. When it is made red-hot in the furnace, it becomes pliable; it can then be welded at the anvil. Wrought iron will bear any amount of tugging and straining. Chains, bridges, arches, and engines are made of it.