- 期刊
SPHC碳鋼熱軋厚鋼捲銹皮鬆脫缺陷解決
A Solution to Scale Loosening of Thick Hot-Rolled SPHC Steel Coils
摘要
熱軋鋼捲理想的表面銹皮層是不易脫落的，若銹皮容易鬆脫，會在重捲線上造成銹皮飛揚；此外，雷射切割時飛揚的銹粉會遮蔽雷射感測器，影響切割品質。中鋼公司6mm以上之高厚度SPHC熱軋產品發生銹皮鬆脫已是長時間之問題，時而嚴重時而趨緩，其發生機構及成因也未真正釐清。為了解決此一陳年問題，本研究由銹皮組織結構分析、現場製程因素釐清、銹皮轉化驗證三大區塊切入。綜合三區塊之結果，確認銹皮之鬆脫與製程中的出爐溫度、完軋溫度、盤捲溫度，以及軋機之軋延力及張力都沒有關係，問題發生在生產之後鋼捲的冷卻過程。銹皮會鬆脫之鋼捲，盤捲後是經過緩冷，內層之FeO有足夠時間轉化成Fe_3O_4；而正常鋼捲之冷速較快，故沒有完全轉化。緩冷之下，所有延性佳之FeO都轉化為延性較差之Fe_3O_4；此外，最終銹皮厚度越厚，故在鋼捲解捲時，上表面受到壓應力之擠壓，緩冷之銹皮就比快冷者容易破裂，因此較易發生銹皮鬆脫。
並列摘要
The ideal oxide scale on the surface of hot-rolled steel coils should remain intact when decoiling. Loosening and peeling-off of oxide scales decrease the laser-cutting efficency by desensitizing the lasers' detecting sensors. China Steel Corporation's hot-rolled coils with thickness greater than 6 mm have oxide scale loosening problem for sometime. The mechanism and cause of oxide scale loosening were unknown and should be investigated. This study focused on product ion process clarification, scale structure analysis, and scale transformation simulation to determine the mechanism and cause of the oxide scale problem. Results showed that the cooling off time is critical for having the scale lossening problem instead of the slab temperature, finishing temperature, coiling temperature, and rolling force and tension. When the coil was slowly cooled to room temperature, the FeO is completely transformed to Fe_3O_4. The Fe_3O_4 forms brittle scales that break off easily when de-coiling. Quick cooling decreases the transformation ratio of Fe_3O_4 scales and thereby lessens the scale loosening problem.