White-crack Segregation in Differential Pressure Casting ZL201A Alloy Housing[J]. Special Casting & Nonferrous Alloys, 2010,30(11):1022-1025.DOI:
差压铸造ZL201A合金壳体铸件“白色裂纹”状偏析的研究
摘要
差压铸造ZL201A合金某壳体铸件探伤时
发现部分铸件上存在"白色裂纹"状偏析组织
经取样观察并采用能谱分析、X射线衍射等检测手段对其进行了成分分析
结果表明
在铸件中偏析的主要元素为Cu和Ti。由于在薄厚交替处的补缩存在困难
热应力较大
所以易产生偏析等铸造缺陷;"白色裂纹"状偏析处聚集的合金是Cu
而Ti的熔点较高
在熔炼过程中由于搅拌不均匀等工艺问题
导致了在合金内部存在Ti的显微聚集区
也是造成偏析的另一原因。应该从熔炼和浇注两方面着手
如使用质量较好的中间合金
减少回炉料的用量
加强搅拌
适当提高浇注温度并改善浇注系统的退让性等
可防止此类缺陷的生成。
Abstract
There exists white-crack segregation in partly differential pressure casting ZL201 Aalloy housings.Microstructure of the housing with white-crack segregation was observed
and chemical composition was examined by EDS(energy dispersive spectrometer) and XRD(X-ray diffraction).The results reveal that segregation in the housing mainly contains Cu and Ti.The creation of segregation is attributed to difficulty in feeding at thin-thick transition location resulting in the larger thermal stress.White-crack segregation is mainly contained Cu element.Meanwhile
there exists Ti segregation zone in some location of alloy as a result of heterogeneous stirring during melting process
which is responsible for the generation of segregation too.Through improving melting process and controlling pouring process
the segregation can be effectively eliminated
including using desirable master alloy
reducing the usage of recycled alloy
strengthening stirring and rationally increasing pouring temperature as well as improving gating system.