问题 问答题 简答题

有两个含碳量为1.2%的碳钢薄试样,分别加热到780℃和860℃并保温相同时间,使之达到平衡状态,然后以大于VK的冷却速度至室温。试问:

哪个温度加热淬火后残余奥氏体较多?

答案

参考答案:

因为加热温度860℃已经超过了Accm,此时碳化物全部溶于奥氏体中,使奥氏体中含碳量增加,降低钢的Ms和Mf点,淬火后残余奥氏体增多。

阅读理解与欣赏
阅读理解

  First Frenchman: I once heard someone shout, "Look out," I put my head out of a window and a basin of water fell on me. It seems that "Look out" may mean "don‘t look out."

  Second Frenchman: Once I was on a ship and heard the captain shout, "All hands on deck," I put my hands on the deck and someone walked on them.

  Third Frenchman: I once visited an English friend early in the morning and the maid who came to the door and said, "He’s not up yet. Come back in half an hour," When I went again for him, she said, "He‘s not down yet."

  "If he’s not up and he’s not down, where is he?" I asked.

  She said, "He’s still in bed. When I say ‘He’s not up ’ I mean ‘he has not yet got up’. When I say ‘He’s not down ’ I mean ‘he has not yet come downstairs,’"

小题1:"All hands on deck" means “ _______ ”.

A.All the sailors gather on deck

B.Give your hands to me

C.Put your right hand and left hand on deck

D.Shake your hands with me小题2:When the maid said, “He’s not up yet.” She meant that _______ .

A.he has not grown up yet

B.he has not yet got up

C.he has not woke up yet

D.he has not yet come upstairs小题3:When the third Frenchman went back, the English friend _______ .

A.was washing his face

B.was having his breakfast

C.was still in an upstairs room

D.was reading a newspaper小题4:Which do you think is the best title for this article?

A.Three Frenchmen and their English Friends

B.The English Language

C.Three French Stories

D.What a Language!