共查询到19条相似文献,搜索用时 187 毫秒
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通过检验对超声波探伤发现的缺陷性质进行确定,从而提高了超声波探伤定性的准确性.由此合理选择锻造工艺参教,如温度、变形量、应力状态等,对超声波探伤缺陷超标的钢材进行了成功的改锻. 相似文献
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采用电渣重熔工艺生产试制了70Cr3Mo钢支承辊辊坯。产品检验结果表明,辊坯的化学成分、超声波探伤、高倍检验全部合格。 相似文献
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邢台钢铁有限责任公司利用具有保护气氛的抽锭式电渣炉生产Ф600 mm的9Cr3Mo冷轧辊钢锭,并锻造成Φ440 mm×1700 mm×4215 mm规格的辊坯,锻造后经超声波探伤发现辊径中心有连续缺陷,直径为Φ4~Φ5 mm,范围长度约为330 mm。采用化学成分分析、金相检验、断口宏观微观检测及酸洗检测等手段对该冷轧辊钢内部探伤缺陷情况进行了全面分析。结果表明,经酸洗后,9Cr3Mo冷轧辊钢心部存在密集的纵向微裂纹,似材料疏松缺陷。进一步检测发现,裂纹附近无脱碳层,周围组织为均匀的球化退火组织,夹杂物无明显异常,无化学成分偏析,排除了电渣锭组织疏松缺陷。而后,对缺陷的特点进行了分析,判定此缺陷为在锻造过程中因心部透烧不充分、材料塑性较低而导致的锻造形变时的拉伸裂纹。最后,通过优化锻造加热过程中每火次间的保温时间和增加操作机抱钳预热的措施,保证了冷轧辊钢心部的锻造温度,避免了此类锻辊的探伤缺陷情况。 相似文献
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针对低合金中厚板超声波探伤合格率低的问题,采用低倍、金相、扫描电镜检验和断口形貌分析对探伤不合格的中厚板进行研究,得出结论:引起超声波探伤不合格的主要原因是钢中的氢含量偏高和板坯中心偏析严重,条状MnS夹杂物集聚氢导致氢致裂纹,板材中心部位因偏析产生的少量马氏体、贝氏体组织导致轧后应力集中,在冷却速度较快的条件下产生微裂纹,最终造成探伤缺陷。通过计算得知MnS夹杂物前端的氢陷阱中氢的浓度远高于陷阱中氢的最大饱和浓度,过剩的氢造成裂纹。采用铸坯及板材轧后缓冷等措施,使板材探伤合格率大幅度提高。 相似文献
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为探明Cr5支承辊出现探伤缺陷的原因,截取本体检测试片,开展组织观察和断口分析,研究了夹杂物微观形貌。结果表明:支承辊心部存在密集性夹杂物缺陷,缺陷呈条状或断续链条状分布;能谱分析结果表明夹杂物主要为Ca和Si的氧化物,是冶炼过程复合脱氧剂形成的脱氧产物。 相似文献
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介绍了支承辊锻件在加工过程中产生外露夹杂物缺陷,采用断口、扫描电镜、能谱分析等手段确定支承辊外露夹杂产生机理,通过优化工艺有效防止了外露夹杂的产生。 相似文献
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对探伤不合格的钢板取样,采用低倍、金相、刨削试验和氢含量测量分析,得出安钢较厚规格的中厚板超声波探伤不合格的主要原因:钢中的氢含量、MnS夹杂物含量较高,铸坯疏松偏析严重以及钢板轧制后冷却速度较快等。采取铁水预脱硫和钙处理控制钢中的MnS夹杂物,钢水经VD炉真空脱气处理,调整连铸机辊缝、轻压下参数以及铸坯、钢板堆放缓冷等措施,厚规格的探伤板合格率提高了12%。 相似文献
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Formation mechanism of shrinkage and large inclusions of a 70t 12Cr2Mo1 heavy steel ingot简 总被引:1,自引:0,他引:1
Shrinkage cavities and large inclusions are serious internal defects of heavy steel ingot and influence the quality of subsequent forgings.In order to remove these two types of defects,a 70 t 12Cr2Mo1 heavy ingot fabricated by vacuum carbon de-oxidation process was sectioned and investigated by means of structure observation and EDS analysis.To further study the forming mechanism of shrinkage and inclusion defects and find possible solutions,simulation on pouring and solidification processes was also carried out using Fluent and ProCAST software,respectively.Results show that the shrinkage defects do not appear in the middle-upper part of the ingot.The critical value of shrinkage cavity criterion is ascertained as 0.013 on the basis of sectioning investigation and simulation results,which can be used in computer simulation to predict and avoid shrinkage defects in production of 12Cr2Mo1 ingots with different weights.However,large inclusions are found at the bottom of the ingot body.The bad thermal conditions of the ingot surface and large amount of entrained slag are the main origin of the large inclusions.The simulation result of the pouring process shows that large inclusions may be eliminated by combined measures of improving the top thermal condition and controlling the height of rudimental molten steel in the ladle to above 300 mm. 相似文献
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Influence of highest degree of cleanliness on the pitting corrosion behaviour of austenitic steels Stainless steel grades of the type material. no. 1.4401, produced in an industrial scale, have been vacuum arc re‐melted up to three times to achieve lowest inclusion contents. These materials have been corrosion tested to get information about the influence of non‐metallic inclusion content on pitting corrosion behaviour. By the use of potentiodynamic polarisation curves on basis of ASTM G61‐86 a clear effect of steel cleanliness was detected. The highest degree of cleanliness and best corrosion behaviour has been achieved with vacuum arc re‐melting material where non‐metallic inclusions are moved to the ingot surface area and minimum gas contents and micro‐segregations are gained. 相似文献
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针对AISI8630钢锻件在实际生产中出现的锻造失效问题进行了研究。采用"EAF→LF→VD→铸锭"工艺冶炼AISI8630钢锭,钢锭锻造成泥浆泵锻件,经热处理加工后探伤发现密集性缺陷。通过化学成分、低倍分析和金相显微分析,对产生的缺陷进行分析研究。结果表明:宏观检测受检面有许多裂纹,将裂纹打开,发现断口存在明显的白点缺陷;近裂纹附近有灰色硫化物夹杂,存在明显的组织偏析现象,远离裂纹处的金相组织无明显差异。通过加强冶炼过程控制,对钢锭进行锻前消氢、消应力退火及锻后250℃以下缓冷处理等工艺优化,避免了白点缺陷的形成,并经现场验证得到合格产品。 相似文献
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Ultrasonic inspection for circumferential butt joint of austenitic stainless steel with carbon steel
0 IntroductionThe flowleading pipe in pusher of shipping diesel en-gine is constructed by butt welding of 1Cr18Ni9Ti auste-nitic stainless steel circumferential strip with low carbonsteel circumferential strip. It is easy to form stress cracks,slag inclusions, and blowholes etc inside the weldedseam. Thus after turning for the weldment it is necessaryto perform nondestructive test for the welded joint.The weldment is very large in dimension and it is adouble deck construction with vertical a… 相似文献