Difficulty: Medium
Correct Answer: Engineers prefer open-hearth steel for structural work because it is more homogeneous and better controlled.
Explanation:
Introduction:
This question contrasts classic steelmaking routes. Open-hearth (Siemens–Martin) historically offered superior control over temperature and composition, yielding homogeneous steels favored for structural members. Bessemer routes varied in impurity removal capability depending on lining (acid vs basic).
Given Data / Assumptions:
Concept / Approach:
Homogeneity and control are key in structural steel. Historically, open-hearth produced reliably uniform steel, while phosphorus removal is effective only with basic linings (Thomas process). Sulphur removal is limited and usually addressed in other stages or by selecting low-S raw materials.
Step-by-Step Solution:
Verification / Alternative check:
Historical specs and texts cite open-hearth's uniformity and the role of basic slags for phosphorus; sulphur control typically requires separate desulphurization or basic open-hearth/BOF practices, not acid Bessemer.
Why Other Options Are Wrong:
Common Pitfalls:
Assuming “all processes remove all impurities”; ignoring the difference between acid and basic linings; conflating phosphorus and sulphur behavior in slag chemistry.
Final Answer:
Engineers prefer open-hearth steel for structural work because it is more homogeneous and better controlled.
Discussion & Comments