国内1215系低碳高硫易切削钢的工艺流程和内部质量控制

对国内100 t EAF-LF-CC和80 t、100 t、160 t转炉-LF-CC四条生产线生产的1215系低碳高硫易切削钢(/%:0.05～0.10C、≤0.013Si、1.06～1.33Mn、0.051～0.061P、0.24～0.36S、0.012 0～0.0140[O]、≤0.005Al)进行实物分析。结果表明,国内1215低碳高硫钢成分控制特点为通过适当提高Mn含量控制钢中的Mn/S (3.7～3.9),个别流程通过降低S含量可使Mn/S达4.4;160 t转炉流程在夹杂物控制上优于其余流程(Mn/S=3.8, MnS夹杂面积和长宽比波动较小)。.由于连铸坯元素偏析较小和轧后冷却速度控制得当,80 t转炉流程和160 t转炉流程生产的钢中无明显的带状组织,而100 t电弧炉流程和100 t转炉流程生产的钢中带状组织级别为3～4。

Process Flow Sheet and Internal Quality Control of Domestic 1215 Low Carbon High Sulphur Free-Cutting Steel

An analysis on the products of 1215 low carbon high Sulphur free-cutting steel (/%: 0. 05 ~ 0. 10C, W 0.013Si, 1.06 ~1.33Mn, 0. 051 -0.061P, 0. 24 ~0. 36S, 0.012 0 ~0. 014 0[O], 0.005Al) produced by domestic 100 t EAF-LF-CC, 80 t, 100 t and 160 t BOF-LF-CC four process production line is carried out. Results show that the control characteristic of domestic 1215 low carbon high Sulphur free-cutting steel is to control Mn/S (3. 7 - 3. 9) of steel by suitable increasing Mn content in steel and for individual flow sheet is by decreasing S content in steel to get Mn/S =4. 4； the inclusion control of inclusion in steel produced by 160 t BOF flow sheet (Mn/S =3. 8, fluctuation of MnS inclusions area and length/width ratio are comparatively smaller) is better than that by others； due to smaller segregation of elements in casting billet and suitable controlling of cooling rate after rolling the steel produced by 80 t BOF flow sheet and 160 t flow sheet has no obvious banded structure, but by 100 t EAF flow sheet and 100 t BOF flow sheet the rating of banded structure is 3 ~4.