摘要
根据对ＹＡＭＡＨＡ１００活塞合金在ＨＴ２００铸铁试验金属型中凝固过程铸件温度场和凝固组织的研究，指出：该合金铸件的凝固方式，随着铸型壁厚Ｓ与铸件模数Ｍ的比值（Ｓ／Ｍ）的增大，有从体积凝固方式向逐层凝固方式转变的趋势，但在先共晶凝固阶段仍以体积凝固方式为主，在共晶凝固阶段，由于温度梯度的增大及共晶凝固温度间隔的减小，凝固方式转为以逐层凝固为主；但当Ｓ／Ｍ值很大（＞５）时，铸件中的温度梯度在共晶凝固阶段又转而变小，削弱了共晶凝固阶段逐层凝固的倾向；铸型的激冷作用使铸件外层初生硅细化，形成组织致密区，组织致密区的相对宽度Ｂ／Ｍ随Ｓ／Ｍ的增大而增大，初生硅的粒度随Ｓ／Ｍ的增大而变细。
The temeperature field of castings of YAMAHA piston alloy in cast iron test metallic mould during solidiication and the structure of solidification were investigated. Theresult shows that the transition in the mode of solidification from volumetric to progressive tend occurs when the ratio of thickness of mould S to modulus of castings M increases. At the stage of pre-eutectic solidification, the freezing takes place mainly by thevolumetic mode; at eutectic solidification stage, the freezing mode mainly is progressivedue to increased temperature gradient and reduced temperature interval of eutectic freezing. But in case of S/M>5, the temperature gradient of eutectic freezing in casting isturned back small, reducing the tendency to progressive freezing. The chilling effect ofmoulds can refine the primary crystal St in the outer layer of castings, forming compactarea, the relative width B/M of which increases with increasing ratio S/M while thegrain size of primary crystal Si reduces with increasing ratio S/M.
出处
《铸造》
EI
CAS
CSCD
北大核心
1995年第12期5-10,共6页
Foundry
