问题 问答题 论述题

试述用碳当量法评定材料焊接时抗冷裂性的局限性?

答案

参考答案:

利用碳当量法评定材料焊接的抗冷裂性有相当大的局限性,具体表现在:(1)如果两种钢材的碳当量值相等,但含碳量不等,则两者的抗冷裂性不同,含碳量低者,产生低碳马氏体,有较高的抗冷裂性;含碳量高者,产生高碳马氏体,抗冷裂性较差。(2)碳当量计算公式只考虑了材料化学成分对冷裂的倾向,没有考虑冷却速度的影响。(3)碳当量计算公式没有考虑热影响区中的最高加热温度和高温停留时间等参数对冷裂倾向的影响。

单项选择题

This was one of my experiences (1) . When I was in my 30s, I was working for a large international company which had its head office in London. I was working in the (2) department.

The company had a training centre which was just outside London. Different courses were held there throughout (3) and I (4) go on one training course a year. These usually started (5) a Sunday evening and lasted six days.

Once I was (6) a week’s training course with about forty (7) sales people. I was in the bar on the Friday evening and suddenly a woman who was (8) behind the bar asked mea curious question. "I hope you don’t (9) my asking," she said, "but I’ve been (10) about it all week. Have you got a sister (11) Mary" The woman’s name was June. And she used to do various jobs at the training centre. She worked in the office, she organized all the food and drink for the centre and she worked in the bar at lunchtime and in the evening.

My answer (12) June’s question was "Yes", and June said, "I thought (13) . I met her last September when she was organizing a course here. " At that time, my sister was working for (14) company but in a different part of the country. That was (15) she came to be at the training centre.

(16) surprised me was how June guessed we were brother and sister. Three things made it even more (17) . First, she had met my sister six months before she met me. Second, they have about sixty new people every week at the training centre. So about one thousand five hundred people had (18) the centre in those six months. And (19) , my sister is married, so she doesn’t have the same family name as me.

We’re not (20) , but I guess we must look quite like each other.

14().

A.the same

B.a different

C.another

D.the other

填空题