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本文对我国中碳铬锰硅钼稀土钢板表面产生锯齿状横向裂纹及断口中含有低倍冶金缺陷本质和成因作了综合性研究。结果表明:造成钢板表面锯齿状横向裂纹是由于钢锭中含有皮下气泡缺陷,在轧制过程中露出钢板表面并沿着轧制方向被拉长形成不连续的孔洞串,终轧后在应力集中作用下扩展成肉眼可见的裂纹。文中重点探讨了皮下气泡微观结构花样和成核长大机制,确定了皮下气泡成核主要靠液态钢中残余氧和少量氮及氢与非金属难溶杂质参加化学反应生成“气孔核”所致。钢锭模的烘烤、除锈不够充分等是引起皮下气泡“气孔核”萌生的重要条件。本工作还找出了消除钢板锯齿状横向裂纹有效措施,并在工业生产中被验证。
In this paper, we made a comprehensive study of the jagged transverse cracks on the surface of medium-carbon chromium-manganese-silicon-molybdenum rare earth steel and the nature and causes of low-rate metallurgical defects in the fracture. The results show that the zigzag transverse crack on the steel plate is caused by the submerged bubble defects in the steel ingot. The surface of the steel plate is exposed during the rolling process and elongated discontinuous holes are formed along the rolling direction. After finishing rolling, the stress concentration Under the expansion of visible cracks. In this paper, the microscopic structure of the sub-bubbles and the mechanism of nucleation and growth are discussed emphatically. It is confirmed that submerged bubbles mainly depend on residual oxygen and a little nitrogen in the liquid steel, and participate in chemical reactions to form “stomatal core” Due. Ingot mold baking, rust enough is caused by subcutaneous bubbles “stomatal core ” an important condition for initiation. This work has also identified effective measures to eliminate serrated transverse cracks in steel and has been validated in industrial production.