。1134 北京科技大学学报 2006年第12期 fects of tempering tem perature and time on the magnetic properties of the alloy were studied.Better mag- netic property of the alloy could be got only under proper tempering condition.After tempered at 635 C for 1h,the coercivity He,the remnant induction B.and the squareness S of the alloy reached 54.2kA'm, 0.19T and 0.79,respectively.M agnetic measurements showed that the difference of coercivity between parallel and perpendicular to the olling direction for the alloy tempered at 635 Cfor Ih,is more significant than those under other tempering conditions.The results indicate that the alloy is a candidate for magnetic scales. KEY WORDS permanent magnet alloy;magnetic properties tempering;magnetic scale Optimization for the structure of BF hearth bottom and the arrangement of ther- mal couples ZHAO Hongbo,CHENG Shusen Metallurgical and Ecological Engineering School,University of Science and Technology Beijing.Beijing 100083.China ABSTRACT The hearth of "heat transfer method"and the ceramic cup synthetic hearth bottom of"heart isolation method"are two most popular designs for blast fumace(BF).Although there are successful real examples,some disadvantages,for instance large heat bss and high cost,still exist for these designs.Ac- cording to the theo ry of heat transfer,based on the calculation of temperature distribution of the hearth bot- tom,it is elucidated that all brick layers at the hearth bottom may not be considered as the only reason why different structures exhibited different temperature dist ributions although total heat resistance is the same, and then based on the effect of hot metal and cold water on different temperature distribution ranges,the concepts of"heat resistance"and "cooling enhancement"are put forth.Based on this,the disadvantages and the factors affecting temperature distribution,of the two types of hearth bottoms were illustrated.On the basis of these analyses,a novel structure for BF hearth bottom designing that can easily for"self-pro- tecting"slag layer stably,called "the method of gradient brick lay out that has an optimum combination of cooling enhancement and heat resistance"was proposed;it can not only prolong the hearth bottom longevity but also reduce the cost and heat loss.Also,the optimum arrangement of thermal couples in hearth bottom was suggested based on the previous studies on erosion prediction carried out by the author. KEY WORDS blast fumace;hearth bottom:longevity design;erosion [Journal of University of Science and Technology Beijing,2006,13(5):497]fects of tempering temperature and time on the mag netic properties of the alloy were studied .Better mag￾netic property of the alloy could be got only under proper tempering condition .After tempered at 635 ℃for 1 h, the coercivity Hc , the remnant induction B r and the squareness S of the alloy reached 54.2kA·m -1 , 0.19 T and 0.79, respectively .M agnetic measurements showed that the difference of coercivity between parallel and perpendicular to the rolling direction for the alloy tempered at 635 ℃for 1h, is more sig nificant than those under o ther tempering conditions .The results indicate that the alloy is a candidate fo r magnetic scales . KEY WORDS permanent mag net alloy ;mag netic properties;tempering ;mag netic scale Optimization for the structure of BF hearth bottom and the arrangement of ther￾mal couples ZHAO Hongbo, CHENG Shusen Metallurgical and Ecological Engineering School, University of S cience and Technology Beijing, Beijing 100083, China ABSTRACT The hearth of “heat transfer method” and the ceramic cup synthetic hearth bottom of “heart isolation method” are tw o most popular designs fo r blast furnace ( BF) .Althoug h there are successful real examples, some disadvantages, fo r instance large heat loss and hig h cost, still exist for these designs .Ac￾co rding to the theo ry of heat transfer, based on the calculation of temperature distribution of the hearth bot￾tom, it is elucidated that all brick layers at the hearth bo ttom may no t be considered as the only reason w hy different structures exhibited different temperature distributions althoug h total heat resistance is the same, and then based on the effect of hot metal and cold w ater on different temperature distribution ranges, the concepts of “heat resistance” and “cooling enhancement” are put forth .Based on this, the disadvantages and the factors affecting temperature distributio n, of the two types of hearth bottoms w ere illustrated .On the basis of these analyses, a novel structure for BF hearth bottom designing that can easily fo rm “self-pro￾tecting” slag layer stably, called “the method of gradient brick lay out that has an optimum combinatio n of cooling enhancement and heat resistance” w as proposed ;it can not only prolong the hearth bottom longevity but also reduce the cost and heat loss .Also, the optimum arrangement of thermal couples in hearth bottom w as suggested based on the previous studies on erosion prediction carried out by the autho r. KEY WORDS blast furnace ;hearth bo ttom ;longevity design ;erosion [ 摘自 Journal of University of Science and Technology Beijing, 2006, 13( 5) :497] · 1134 · 北 京 科 技 大 学 学 报 2006 年第 12 期