中国材料进展
中國材料進展
중국재료진전
MATERIALS CHINA
2014年
6期
355-360
,共6页
铝合金%铸造缺陷%孔洞%热裂%模型
鋁閤金%鑄造缺陷%孔洞%熱裂%模型
려합금%주조결함%공동%열렬%모형
aluminum alloys%solidification defects%microporosity%hot cracking%model
孔洞与热裂是铸件在凝固过程中最常遇到的典型缺陷。两者均形成于合金凝固末期，与液相补缩不足相关，但又有各自的形成机理。铝合金熔体对氢气有很大的溶解度，凝固过程中又因为溶解度的剧降而析出。孔洞是液相中过饱和的气体压力与凝固收缩引起的压力降共同作用的结果。热裂则是在凝固末期由于铸件收缩受阻而产生的应力以及液相补缩不足而导致的，其不仅与合金性质、铸造条件有关，并且受铸件形状的影响。文章基于近年来该方面的理论研究成果，总结了关于孔洞与热裂的形成机理以及几种目前所应用的经典预测模型，并对这几种模型的理论基础以及所考虑的关键参数进行了分析与讨论，在此基础上提出了未来新模型的研究方向和亟需解决的关键问题。
孔洞與熱裂是鑄件在凝固過程中最常遇到的典型缺陷。兩者均形成于閤金凝固末期，與液相補縮不足相關，但又有各自的形成機理。鋁閤金鎔體對氫氣有很大的溶解度，凝固過程中又因為溶解度的劇降而析齣。孔洞是液相中過飽和的氣體壓力與凝固收縮引起的壓力降共同作用的結果。熱裂則是在凝固末期由于鑄件收縮受阻而產生的應力以及液相補縮不足而導緻的，其不僅與閤金性質、鑄造條件有關，併且受鑄件形狀的影響。文章基于近年來該方麵的理論研究成果，總結瞭關于孔洞與熱裂的形成機理以及幾種目前所應用的經典預測模型，併對這幾種模型的理論基礎以及所攷慮的關鍵參數進行瞭分析與討論，在此基礎上提齣瞭未來新模型的研究方嚮和亟需解決的關鍵問題。
공동여열렬시주건재응고과정중최상우도적전형결함。량자균형성우합금응고말기，여액상보축불족상관，단우유각자적형성궤리。려합금용체대경기유흔대적용해도，응고과정중우인위용해도적극강이석출。공동시액상중과포화적기체압력여응고수축인기적압력강공동작용적결과。열렬칙시재응고말기유우주건수축수조이산생적응력이급액상보축불족이도치적，기불부여합금성질、주조조건유관，병차수주건형상적영향。문장기우근년래해방면적이론연구성과，총결료관우공동여열렬적형성궤리이급궤충목전소응용적경전예측모형，병대저궤충모형적이론기출이급소고필적관건삼수진행료분석여토론，재차기출상제출료미래신모형적연구방향화극수해결적관건문제。
Porosity and hot tearing are representative defects in solidification of shape castings .They are all related to lacking of feeding at the final stage of solidification but have different forming mechanisms .The hydrogen has high solubili-ty in melt of aluminum alloy but will be released during solidification .The supersaturation pressure of the gas and pressure drop induced by solidification shrinkage all contribute to the formation of porosity .Hot tearing usually occurs due to bloc-king of shrinkage and lacking of feeding, and is related to alloys properties, casting technology in the shaping of castings. Based on the fundamental researches of solidification , formation mechanisms and several classical prediction criterions of these two types of solidification defects were generalized .Analyses and discussion were done for the formation criterion and key parameters.Finally the research directions of new criterion and the problems to be resolved immediately were given .
