Grain Refinement and Improvement of Solidification Defects in Direct-Chill Cast Billets of A4032 Alloy by Melt Conditioning

被引：33

作者：

Li, Hu-Tian ^{[1
]}

Zhao, Pizhi ^{[2
]}

Yang, Rongdong

Patel, Jayesh B. ^{[1
]}

Chen, Xiangfu ^{[3
]}

Fan, Zhongyun ^{[1
]}

机构：

[1] Brunel Univ London, BCAST, Uxbridge UB8 3PH, Middx, England

[2] Chinalco Mat Applicat Res Inst Co Ltd, Beijing 100082, Peoples R China

[3] Southwest Aluminum Grp Co, CHINALCO, Chongqing 401326, Peoples R China

来源：

METALLURGICAL AND MATERIALS TRANSACTIONS B-PROCESS METALLURGY AND MATERIALS PROCESSING SCIENCE | 2017年 / 48卷 / 05期

基金：

英国工程与自然科学研究理事会;

关键词：

AL-SI ALLOYS; ALUMINUM-ALLOYS; MACRO SEGREGATION; FLUID MOTION; MACROSEGREGATION; MECHANISMS; CONVECTION; INGOTS; FLOW; INOCULATION;

D O I：

10.1007/s11663-017-1016-7

中图分类号：

T [工业技术];

学科分类号：

08 ;

摘要：

Melt-conditioned, direct-chill (MC-DC) casting is an emerging technology to manipulate the solidification process by melt conditioning via intensive shearing in the sump during DC casting to tailor the solidification microstructure and defect formation. When using MC-DC casting technology in an industrial scale DC cast billet of an A4032 aluminum alloy, significant grain refinement and uniform microstructure can be achieved in the primary alpha-Al phase with fine secondary dendritic arm spacing (SDAS). Improved macrosegregation is quantitatively characterized and correlated with the suppression of channel segregation. The mechanisms for the prevention of channel segregation are attributed to the increased local cooling rate in the liquid-solid phase region in the sump and the formation of fine equiaxed dendritic grains under intensive melt shearing during MC-DC casting. A critical cooling rate has been identified to be around 0.5 to 1 K/s (A degrees C/s) for the channel segregation to happen in the investigated alloy based on quantitative metallographic results of SDAS. Reduction and refinement of microporosity is attributed to the improved permeability in the liquid-solid phase region estimated by the Kozeny-Carman relationship. The potential improvement in the mechanical properties achievable in MC-DC cast billets is indicated by the finer and more uniform forging streamline in the forgings of MC-DC cast billet.

引用

页码：2481 / 2492

页数：12

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