问题 问答题

正火的定义及目的?

答案

参考答案:

①正火是将钢加热到Ac3以上(亚共析钢)30~50摄氏度或Acm以上(过共析钢)30~50摄氏度,保温后在空气中冷却的热处理方法。②正火的目的:对于不太重要的零件,正火可作为最终处理工艺,其机械性能可满足要求;改善低碳钢的切削加工性能;对于共析钢,正火可以减少或消除网状渗碳体。

单项选择题
单项选择题

"Europe needs to import to export. " That is the slogan of the European Commission’s new strategy for securing its economic place in the world, unveiled this week by Peter Mandelson, the European Union’s commissioner for trade. The soundbite, of course, gets the economics precisely backwards: exports are the price a country must pay for its imports; Europeans toil away making stuff for others to consume only so they can in turn get their hands on the fruits of foreign labours.

But the slogan does capture two awkward truths European exporters must now confront. First, only by offering to open its own markets can the EU hope to persuade foreign countries to open theirs. But with the collapse of the Doha round of trade talks, it is not obvious to whom the Europeans should make their offers. Second, European companies are now part of elaborate global supply chains. Clumsy efforts to protect some of them from foreign competition deprive others of the cheap inputs they need to thrive in world markets.

The new trade strategy looks at both of these dilemmas, among others. Though Mr Mandelson insists that he remains wedded to multilateral negotiations at’the World Trade Organisation, he also fancies pursuing a bit on the side with other willing trade partners. The EU will pick its partners according to three criteria: do they offer a big, growing market Are they cutting deals with America or Japan And are they guilty of deterring European companies, either repelling them at the border with high tariffs, or bogging them down in cumbersome rules and regulations The strategy names ASEAN, South Korea, India and Russia as priorities, as well as two regional blocks, Mercosur and the Gulf Co-operation Council, that it is already courting. The EU will reveal its plans for China at the end of the month.

The strategy also proposes to look again at how the EU protects its own borders, because its favored weapons are prone to backfire. For example, EU ministers decided this week to slap antidumping duties on leather shoes from Vietnam and China, which threaten shoemakers in Italy, Portugal and Spain. But the duties are opposed by Europe’s own retailers and some of its sportswear makers. Letting Asian workers stitch and glue sports shoes makes it possible for such firms to employ Europeans to design and market them.

Mr Mandelson presented his strategy as a way to help the EU become more competitive. Opening up to foreign rivals is, of course, an excellent way to foster competition in cloistered domestic industries. A pity then that most of his concrete proposals were about conquering markets abroad, and that the EU is still so ready to raise its defences at home.

Which of the following is not a basic standard of EU for picking its partners()

A. Offering a big, growing market.

B. Not bogging them down in cumbersome rules and regulations

C. Not deterring European companies from their countries

D. Cutting deals with America or Japan