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厂家对nd钢管一般斑点状偏析成因解决方法

发布时间:2019-05-20人气:19

对ND钢管一般斑点状偏析的成因分析:根据试验分析,结合nd钢管锻造生产情况,在排除一般疏松、气体过饱和、钢液纯净度太差等因素后,通过金相及能谱分析,发现点偏处组织有别于基体组织,如晶粒细化,硬度偏高(达310~340HV),组织也非珠光体正常组织,从而认为现有的点偏缺陷实质是受合金成分偏析导致的组织偏析。
Analysis of the causes of the general speckle segregation of ND steel pipes: According to the experimental analysis and combined with the forging production of ND steel pipes, after excluding the factors such as general porosity, gas supersaturation and poor purity of molten steel, metallographic and energy spectrum analysis showed that the structure at the point deviation was different from the matrix structure, such as grain refinement, high hardness (310-340HV), and the structure was not normal pearlite structure. It is believed that the existing point segregation defect is essentially the segregation of the structure caused by the segregation of the alloy composition. 酸浸塔形分析:将带点偏缺陷的nd钢管改锻成Φ210mm,取Φ210mm×200mm样坯车削成4级等长台阶(一级Φ150mm,二级Φ130mm,三级Φ110mm,四级Φ90mm),做酸浸塔形检测,在锻材Φ110mm、Φ90mm两级台阶上发现明显的类似于垫片的纵向暗条,而Φ150mm,Φ130mm两级台阶上纵向暗条纹则不明显。
Acid leaching tower shape analysis: the ND steel pipe with point deviation defect was forged into 210 mm, and the sample blank of 210 mm * 200 mm was turned into four equal-length steps (first 150 mm, second 130mm, third 110 mm, fourth 90 mm). The acid leaching tower shape detection was carried out. The vertical dark stripes similar to gaskets were found on the forged steel 110 mm and 90 mm steps, while the vertical dark stripes on the two steps of 150 mm and 90 mm were found. It is not obvious.

气体检测:根据所收集的5炉钢相关气体的检测数据发现,点偏的出现及级别与nd钢管中气体含量并无直接关系。
Gas Detection: According to the collected data of gas related to 5 stoves of steel, it is found that the occurrence and grade of point deviation is not directly related to the gas content in ND steel pipe.

金相分析:在酸洗过的低倍试样上点偏缺陷密集部位切取金相试样进行高倍分析;对nd钢管试样进行抛光、高倍轻腐蚀后观察宏观形貌;将试样偏析部位标识后再次进行低倍酸浸重腐蚀试验。上述金相分析结果表明,偏析区组织类似于贝氏体组织,基体为珠光体+铁素体;扫描电镜下观察,组织明显存在不均匀,进一步放大倍数观察,通过对点偏缺陷位置处能谱分析,发现了以MnS为代表的夹杂物的偏聚。
Metallographic analysis: metallographic specimens were cut at the point defect-intensive part of pickled low-power specimens for high-power analysis; ND steel tube specimens were polished and observed after high-power light corrosion; the segregation parts of the specimens were marked and the heavy corrosion test of low-power acid leaching was carried out again. The metallographic analysis results show that the segregation zone is similar to bainite structure, and the matrix is pearlite + ferrite. The structure is obviously inhomogeneous under scanning electron microscopy, and further magnification observation. The segregation of inclusions represented by MnS is found by energy spectrum analysis at the location of the point deviation defect.

结合上述分析结果,排除了点偏为一般疏松误判的可能,也排除了由于气体过饱和所引起的nd钢管点状偏析的可能,还排除了钢液纯净度太差,夹杂物偏聚所致形成点状偏析的可能。
Combined with the above analysis results, the possibility of misjudgement of point deviation for general looseness is excluded, the possibility of point segregation for ND steel tube caused by gas supersaturation is also excluded, and the possibility of point segregation caused by poor purity of molten steel and inclusion segregation is also excluded.


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