摘要
对某大型ZL205A异型差压铸造壳体进行X射线铸件探伤时发现,壳体局部区域出现偏析、缩松等缺陷。以铸造缺陷为对象,统计了缺陷产生的部位以及对铸件力学性能的影响,并通过取样观察、金相组织、扫描电镜观察以及能谱分析等手段对缺陷产生原因进行分析。结果表明,铸造缺陷主要集中在隙缝浇道附近,缩松和偏析缺陷部位均有不同程度的合金元素富集,并且缺陷组织的形成严重降低了材料的力学性能。断口观察发现,正常试样断口出现了较多的韧窝及河流花样,呈现韧性及准解理断裂的混合断裂特征,而缩松及偏析试样的断口呈明显的解理台阶及沿晶断裂的脆性断裂特征。结合工艺过程分析认为,缺陷的产生主要是和铸造收缩应力、温度场温度过高以及精炼不充分有关。讨论了铸造缺陷产生的机理,并提出了降低热应力、避免出现组织过热、促进合金均匀分散的有效预防措施。
Partial segregation and shrinkage defects appear in local areas of a large counter-pressure ZL205A alloy shell with abnormity figure during X-ray casting inspection.The casting defects were analyzed,and the parts where defects are observed were recorded and the influence on mechanical properties of the castings was analyzed.The origination analysis for defect parts were conducted by sampling observation,metallographic structure,scanning electron microscopy observation(SEM),energy spectrum analysis and other detection methods.The statistical results reveal that the casting defects are mainly concentrated in the vicinity of the slot ingate,and alloy elements are enriched with different degree in the shrinkage and segregation defect parts,and the defect formation is seriously harmful to the mechanical properties of production.Meanwhile,the fracture observation results reveal that there exist more dimples and river pattern in normal specimens,which are characterized by mixed fracture of toughness and quasi-cleavage fracture,while obvious cleavage steps and intergranular fracture are observed on loose and segregation specimens.Combined with the process analysis,the defects are mainly caused by shrinkage stress of casting,high temperature field and insufficient refining.The mechanism of casting defects formation was discussed,and effective preventive measures were provided including reducing thermal stress,avoiding microstructure overheating and promoting uniform dispersion of alloy components.
作者
曹喜娟
任广笑
刘永哲
李沛森
郑云凯
CAO Xijuan;REN Guangxiao;LIU Yongzhe;LI Peisen;ZHENG Yunkai(Shanxi Jianghuai Heavy Industry Co.,Ltd.,China State Shipbuilding Corporation,Jincheng 048000)
出处
《特种铸造及有色合金》
CAS
北大核心
2024年第11期1579-1584,共6页
Special Casting & Nonferrous Alloys
关键词
ZL205A合金
差压铸造
缩松
偏析
形成机理
ZL205A Alloy
Counter-pressure Casting
Shrinkage
Segregation
Formation Mechanism
