摘要
针对矿山机械用机架前座产生的裂纹,采用光学显微镜、场发射扫描电镜和能谱仪,对裂纹产生的原因进行分析。结果表明,裂纹两侧存在脱碳层,裂纹是铸件在凝固过程中产生的热裂纹,包含氧化夹杂物Fe_(2)O_(3)、MnO、Na_(2)O、CaO的密集双层膜是裂纹源。分析原因可知,在钢液凝固过程中,裹携氧化夹杂物的双层膜从钢液表层渗入内部,并汇聚在晶粒之间。枝晶骨架收缩时,受到型芯的阻碍而产生收缩应力。在高温下,当双层膜位置的集中应变无法满足合金收缩需求时,便会在这个厚度微小的薄弱区域产生裂纹。结合显微组织及裂纹原因分析,采取改善内浇道与冒口位置及分布、采用复合稀土脱氧、精炼合金、加强原材料质量管控、提高作业人员水平和加强炉渣控制等措施,是减少热裂纹产生的有效途径。
Aiming for the cracks in the front seat of the rack for the mining machinery,the Zeiss microscope,field emission scanning electron microscope,and energy spectrometer are used to analyze the causes of the cracks.The results show that the decarburization layers exist on both sides of the crack.The crack is a hot tearing one produced during the solidification process of the casting and contains oxide inclusions.The dense bi-film with Fe_(2)O_(3),MnO,Na_(2)O,and CaO is the source of the crack.Analyzing the reason,it can be seen that during the solidification process of the steel liquid,the double-layer films wrapped with oxide inclusions penetrate from the surface layer into the interior of the steel liquid and converge between the grains.The contraction of the skeletons of dendrites are hindered by the sand cores or mold,resulting in shrinkage stress.At high temperature,when the concentrated strain at the position of the double-layer film cannot meet the shrinkage requirements of the alloy,cracks will occur in the weak areas with small thicknesses.Combined with the analysis of the microstructures and crack causes,improving the position and distribution of the ingates and feeders,deoxidizing by using of composite rare earth and refining alloys,strengthening the quality control of raw materials,improving the operators′skills,and strengthening slag control are effective ways to reduce the generation of hot tearing cracks.
作者
宋志起
刘健明
贾旭
邹寅
SONG Zhi-qi;LIU Jian-ming;JIA Xu;ZOU Yin(CRRC Qishuyan Rolling Stock Technology Research Institute Co.,Ltd.,Changzhou 213011,Jiangsu,China;Jiangsu Langrui Maoda Casting Co.,Ltd.,Jiangyin 214445,Jiangsu,China)
出处
《铸造》
2025年第12期1606-1610,共5页
Foundry
关键词
机架前座
裂纹
脱碳层
氧化夹杂物
front seat of the rack
crack
decarburization layer
oxidation inclusions
