JNTU IV B.Tech I Semester Supplimentary Examinations, February 2008
(Metallurgy & Material Technology)
1. (a) What is the general principle underlying the development of Acid Bessemer process.
(b) Give the chemical reactions that are responsible for exothermicity in Acid Bessemer process.
(c) What is metallic yield? How do you calculate metallic yield in an Acid Bessemer converter?
2. (a) How is dephosphorisation rate increased in a LDAC process? Explain it with the help of chemical reactions.
(b) How are the decarburisation and dephosphorisation controlled by lance-movement?
(c) What practice has to be followed to obtain extra low ’P’ steel in LDAC process?
3. (a) With the help of chemical reactions, explain the chemistry of steel refining process?
(b) Which reactions is different from all other chemical reactions during impurity oxidation in steel making? Explain?
4. (a) What is meant by external desulphurisation of hot-metal? Why is it desirable?
(b) What is desulphurisation-index? Why is desulphurisation considered very low in steel making processes? Compare value of Ds under blast furnaces conditions and basic steel making conditions.
5. (a) Explain the differences between an active-mixer and an inactive mixer.
(b) What is difference in charge composition between Blast Furnace hot metal and Active Mixer-metal.
(c) What is the advantage of Active mixer practice over ladle desiliconisation.
6. Classify scraps on the basis of chemistry from the point of view of steel making. Among the classification, which scraps lead to the problem of residuals?
7. (a) Why is the secondary steel making termed as ladle-metallurgy?
(b) Explain the duplexing process of secondary steel making.
8. Explain any two of the following recent trends in continuous casting.
(a) Continuous – Continuous casting
(b) Combination caster
(c) Near-net shape casting