问题 问答题 简答题

球罐使用高强度钢要着重考虑哪些性能?

答案

参考答案:

(1)焊接性能这个性能可用焊接热影响区的最高硬度维氏硬度Hmax或与该值有关的碳当量(Ceq)等表示。

Ceq=C+Mn/6+Si/24+Ni/40+Cr/5+Mo/4+V/14(%)

Ceq与Hmax之间存在如下关系式:

Hmax=(666×Cep+40)±40

对高强度钢进行焊接性能试验时,应进行碳当量、焊缝最高硬度及焊道弯曲试验。碳当量不符合该规范要求时,则应进行焊缝最高硬度试验。上述两项试验都不符合该规范要求时,则应进行焊道弯曲试验,上述各项试验依此进行,如其中有一项合格,则可以肯定这种钢是合格的。近年,伊藤庆典等在试验基础上,提出用钢材焊接裂缝敏感性指数Pc来估计焊接裂缝出现的可能性。Pc=C+Si/30+Mn/20+Cu/20+Ni/60+Cr/60+Mo/15+V/10+5B(%)

(2)韧性

一般地说,钢的强度越高,则韧性差,而且易脆,有脆性断裂的危险。为此,要求高强钢有良好的韧性。

阅读理解

We are all busy talking about and using the internet. But how many of us know the history of the internet?

Many people are surprised when they find that the internet was set up in the 1960’. At that time, computers were large and expensive. Computer networks didn’t work well if one computer in the network broke down. Then the whole network stopped. So a new network system had to be set up. It should be good enough to be used by many different computers. If one part of the network was not working , information could be sent through another part. In this way computer network system could keep on working all the time.

At first the internet was only used it, too. However, computers were still very expensive and the internet was difficult to use. By the start of the 1990’s, computers were still very expensive and the internet was difficult to use. By the start of the 1990’s, computers had become cheaper and easier to use. Scientists had also developed software that made “surfing “ the internet more convenient.

Today it is easy to get online and it is said that millions of people use the internet every day. Sending e-mail is more and more popular among students. The internet has now become one of the most important parts of people’s life.

小题1:The Internet has a history of more than        years.

A.ten

B.twenty

C.forty

D.sixty小题2:A new network system was set up to        .

A.make computers cheaper

B.make computers expensive

C.make itself keep on working all the time

D.make computers large小题3:At first the Internet was only used by        .

A.the government

B.universities

C.hospitals

D.schools小题4:What does “convenient” mean in the passage?

A.便宜的

B.昂贵的

C.方便的

D.困难的小题5:Today        than before.

A.fewer people are using computers

B.it is more difficult to get online

C.sending e-mail is more popular

D.computers are more expensive

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