摘要
文章采用拉伸试棒断裂分析、氢含量测量和夹杂物分析等方法,研究了A356.2合金转向节差压铸造(CPC)过程中的熔体质量。拉伸试棒的失效模式表明,氧化物是CPC铸造A356.2-T6转向节中最有害的夹杂物。使用Hycal分析设备对各个阶段的氢含量进行量化分析,发现除气后氢含量急剧下降至(0.16±0.01)mL/100 g,随后保温和CPC过程中略有增加。采用多微孔圆盘过滤装置(PoDFA)法识别不同类型的夹杂物,包括TiB_(2)、Al_(4)C_(3)、α-Al_(2)O_(3)、尖晶石状、尖晶石、氧化膜和MgO。不同夹杂物的含量分析表明,除气过程可以有效去除氧化物,但当熔体在升液管中上下移动时,氧化物很容易重新形成。讨论了熔池的特性和不同CPC循环中的熔渣形成机制,从而全面了解了从第一个铸造周期到最后一个铸造周期中氧化物尺寸和浓度的增加,这导致熔体质量以及铸造质量的恶化。因此,在CPC工艺中,必须尽量减少氧化并限制液面升降速度,以确保生产高质量铸件。
The melt quality of A356.2 alloy during the pressure counter pressure casting(CPC)process for steering knuckles is investigated through fracture analysis of tensile test bars,hy⁃drogen content measurement,and inclusion analysis.The failure modes of the tensile test bars sug⁃gest that oxides are the most detrimental inclusions in the CPC cast A356.2-T6 steering knuckles.Hy⁃drogen content at various stages is quantified using the Hycal analysis apparatus,revealing a sharp decrease to(0.16±0.01)mL/100 g after degassing,followed by a slight increase in the holding and CPC process.The porous disc filtration apparatus(PoDFA)method is employed to identify different types of inclusions,including TiB_(2),Al_(4)C_(3),α-Al_(2)O_(3),spinel-like,spinel,oxide films,and MgO.The content of different inclusions analysis indicates that oxides can be effectively removed during degas⁃sing,but can easily re-form as the melt moves up and down in the riser tubes.The characteristics of the molten bath and the mechanism of slag formation in different CPC cycles are discussed,which provides a comprehensive understanding of the increase in oxide size and concentration from the first to the last casting cycle.This increase leads to a deterioration of the melt quality as well as the casting quality.It is thus essential to minimize oxidation and limit the liquid front velocity to ensure the con⁃sistent production of high-integrity castings in the CPC process.
作者
刘峰
吴斌
雷益宇
刘利兵
LIU Feng;WU Bin;LEI Yiyu;LIU Libin
出处
《上海汽车》
2025年第12期39-51,共13页
Shanghai Auto
