问题 问答题 论述题

影响钢水氧含量的因素有哪些?

答案

参考答案:

吹炼终点钢水氧含量也称为钢水的氧化性。钢水氧化性对钢的质量、合金吸收率以及对沸腾钢的脱氧,都有重要的影响。

影响钢水氧含量的因素主要有:

(1)钢中氧含量主要受碳含量控制。碳含量高,氧含量就低;碳含量低时,氧含量相应就高;它们服从碳—氧平衡规律。

(2)钢水中的余锰含量也影响钢中氧含量。在ω〔c〕<0.1%时,锰对氧化性的影响比较明显,余锰含量高,钢中氧含量会降低。

(3)钢水温度高,增加钢水酌氧含量。

(4)操作工艺对钢水的氧含量也有影响。例如高枪位,或低氧压,熔池搅拌减弱,将增加钢水的氧含量,当ω〔c〕<0.15%时,进行补吹会增加钢水氧含量;拉碳前,加铁矿石或氧化铁皮等调温剂,也会增加钢水氧含量。因此,钢水要获得正常的氧含量,首先应该稳定吹炼操作。

选择题
填空题

Bush’s MBA


Twenty-six of 42 presidents, including Bill Clinton, were lawyers. Seven were generals. George W. Bush becomes the first with an MBA.
Those who have had Bush for a boss since the mid-1980s—in the (1) of oil, baseball and Texas state government—describe his management (2) as straight from the pages of the organizational-behavior (3) he studied while getting his masters of business administration (4) at Harvard University in 1975.
He manages by what is known (5) "walking around," having learned that sitting behind a desk and passing out memos does (6) to energize anyone.
He has a reputation for fueling "creative tension" (7) his subordinates, encouraging them to take and defend opposing (8) . That sacrifices harmony, but puts ideas to the test and lets Bush (9) above the fray, where he can offer guidance instead of barking (10) . Imagine the creative tension that may erupt (11) the likes of Secretary of State-designate Colin Powell and Defense Secretary— (12) Donald Rumsfeld.
Above all, former employees say that he is a master at delegating (13) installing measures of accountability—ways of knowing (14) subordinates are getting the job done without looking (15) any shoulders. That frees Bush for strategic thinking—perhaps (16) two words hammered into MBA students most—which means thinking (17) to seize opportunities and to derail threats to the best of plans.
"George was my (18) ," says Tom Schieffer, who served as president of the Texas Rangers under Bush (19) 1991 and 1995. "But he never made me feel that way. He went out of his way to treat me as a (20) , not a subordinate."
That’s one trait that might be of concern, says Michael Useem, director of the Wharton Center for Leadership and Change at the University of Pennsylvania. It’s important for subordinates to feel part of the team, but not just because the boss craves popularity. Just as in the military, it must be understood who is in charge when the final order is given.