ارزيابي فني و اقتصادي توليد غلتك هاي ريختگي از جنس فولاد تندبر براي نورد مقاطع كوچك

چكيده انگليسي :

Metallurgical and Marketing Evaluation of Production High Speed Steel Cast Rolls for Light Section Rolling Mill Zahra Babaei Esfarjani Pekten 169@yahoo com August 27 2011 Isfahan University of Technology 8415683111 Isfahan Iran Degree M Sc Language Farsi Dr Fakhreddin Ashrafizadeh Prof Supervisor E mail ashrafif@cc iut ac ir Dr Farimah Mokhatab Rafiei Assistant Prof Supervisor E mail farimah@cc iut ac irAbstractOne of the methods in product of steel sections is to supply the raw materials to manufate of constructiveof frame rolling mill systems and specially hot rolling mills Considering that these collections forminghot steels with using of specials rolls so contiguous of production is very important conversely forging one of the biggest problems in steel sections hot rolling mills is stoppings in production mills whichoccures because of the replacement of rolls in rolling mill stands For along time this problem had been asa big problem for industrial workers and they always has tried to access to new alloys for rolls manufacturein order to working more stability so with this method the period of mills stop increases and generallydecreases the total of stops At the start of work primary factors such as resisitance to treatment stabilityand surface hardness have guided the manufactures of roll to use of casting rolls From the first of usablealloys can to point to definite and indefinite chill cast irons which have a lot of different carbides in themselves and they have not a suitable life So industrial workers of rolling mills always have tried to accessto new alloys with along life for using in finishing stands of rolling mill in which roll should has a highwear resistance such as modified indefinite chill cast iron with matrix of binite martensite The newest usable alloys in manufacturing of rolls in small section mills such as cornered strap and barmill are high chromium cast iron and high speed steels These rolls have effect on quality of finishingproducts in addition to production speed In the first part of this research metallurgical and technicalaspects of cast rolls made in high speed steel have been evaluated and compared with conventional alloygrades indefinite chill cast iron with matrix of binite indefinite chill cast iron with matrix of martensite high chromium definite chill cast iron Samples of the selected grades were cast and heat treated formechanical tests hardness and impact and microstructural examination by optical and scanning electronmicroscopy SEM The wear resistance of the samples was evaluated by a pin on disc machine Experimental results in all tests confirmed better wear resistance of high speed steel alloy grade ascompared to other alloys Microstructural studies showed that high speed steel samples had a dispersion offine carbides in tempered martensite matrix High speed steel and high chromium samples also had thesame impact energy and hardness in mechanical testing and high speed steel the best wear resistance atthree different loads So have been decreased from the weight of pin and have been increased to thesurface of disc by the form of sticky particles In the second part of research the economical aspects ofusing high speed steel rolls were considered in small section mills and marketing in the middle east andNorth Africa After introducing the mill companies and their classifications based on production above150000 tons a questionnaire was prepared The results of statistical analysis indicated that market wasvirgin for this kind of product and a good opportunity is expected for this market Then in this research toinvest capital and attend to the production of high speed steel as a chance in the market descriptive plan andeconomic evaluation has been supplied for spadana Ghaltakrizan Co and the activity of this company isthe field of product in small section rolling mills with the grade of high speed steel The above evaluationwhich has been supplied in the form of financial sheets is the con

بابايي اسفرجاني، زهرا

ارزيابي فني و اقتصادي توليد غلتك هاي ريختگي از جنس فولاد تندبر براي نورد مقاطع كوچك

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