Inclusion analysis in magnesium free-cutting steel
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摘要: 为了探究Mg处理对易切削钢中夹杂物的影响,以1144高硫易切削钢为试验钢种,采用金相和能谱仪等手段研究了Mg处理对1144易切削钢中夹杂物的形态、尺寸分布和夹杂物成分的影响。结果表明:在易切削钢铸坯中,Mg处理使得易切削钢铸坯硫化物夹杂由Ⅱ类向Ⅲ类、Ⅰ类转变,分布更为均匀,同时使得复合硫化锰夹杂物比例提升。在轧材中,使得钢中夹杂物球化,并且钢中硫化锰夹杂物的尺寸和分布也得到了较好的改善,同时,Mg处理能够有效提高易切削钢的切削加工性能。Abstract: In order to explore the influence of Mg treatment on inclusions in free-cutting steel, 1144 high-sulfur free-cutting steel was used as experimental steel, and the influence of Mg composite treatment on the shape, size distribution and inclusion composition of free-cutting steel 1144 was studied by means of metallography and energy spectrometer. Experimental results show that in the free-cutting steel slab, due to Mg treatment sulfide inclusion changes from class Ⅱ into class Ⅲ and class Ⅰ, and becomes more uniform distribution, at the same time the amount of composite MnS inclusion increases. During rolling the inclusion becomes spheroidization, and its size and distribution of manganese sulfide inclusions has been improved. It is concluded that Mg treatment can effectively improve the machining performance of studied free cutting steel.
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Key words:
- free cutting steel /
- MnS /
- inclusion /
- Mg treatment
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表 1 1144易切削钢试验钢种成分要求
Table 1. 1144 test steel composition requirements for free cutting steel
% C Si Mn P S 内控指标 0.43~0.47 0.18~0.25 1.45~1.52 <0.025 0.24~0.30 目标 0.45 0.22 1.47 0.27 表 2 夹杂物统计数据
Table 2. Statistics of inclusions according to its size
传统工艺 新工艺(Mg处理) 夹杂物平均面积/μm2 夹杂物等效直径/μm 夹杂物密度/(个·mm−2) 夹杂物平均面积/μm−2 夹杂物等效直径/μm 夹杂物密度/(个·mm−2) 中心 13.909 3.873 1169 16.412 4.245 1101 1/4处 16.858 4.091 1211 18.065 4.334 1065 边部 16.431 4.395 864 16.343 4.10 695 表 3 铸坯中夹杂物类型统计
Table 3. Statistics of inclusion types in billets
类型 对比炉 试验炉 个数 比例/% 个数 比例/% 单纯MnS 564 97.2 553 93.9 复合夹杂物 16 2.8 36 6.1 Al-O-MnS复合硫化物 14 2.5 0 0 Mg-Al-O-MnS复合硫化物 2 0.3 10 1.7 Mg-Al-Ca-Si-O-MnS复合硫化物 0 0 26 4.4 表 4 轧材A类夹杂物评级结果
Table 4. Results of grade inclusions of rolled steel
炉次 对比炉次 试验炉次 细系长度/μm 细系评级 粗系长度/μm 粗系评级 细系长度/μm 细系评级 粗系长度/μm 粗系评级 1 2690 5.5 1647 4.0 2110 4.5 1317 2.5 2 2291 5.0 2434 5.0 2682 5.5 890 2.5 3 2206 4.5 1569 4.0 2369 5.0 1167 2.0 4 2108 4.5 1741 4.0 1 999 4.5 1719 4.0 5 2296 5.0 1658 4.0 2537 5.0 1690 4.0 6 2845 5.5 1562 4.0 2431 5.0 1795 4.0 7 3341 6.0 2292 5.0 2606 5.0 1322 2.5 8 2911 5.5 2242 5.0 2766 5.5 1564 4.0 表 5 切削试验参数
Table 5. Parameters of cutting test
进给量f/(mm·r−1) 切削深度aq/mm 转速w/(r·min−1) 0.19 1 180 0.19 1 560 0.09 1 560 0.09 1 1200 -
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