Effects of Varied Ultrasonic Semi-continuous Casting on Microstructure and Mechanical Properties of ZK60 Magnesium Alloy

Zhang Haijing; Chen Xingrui; Le Qichi

doi:10.15980/j.tzzz.2018.03.015

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Effects of Varied Ultrasonic Semi-continuous Casting on Microstructure and Mechanical Properties of ZK60 Magnesium Alloy
Vol. 38, Issue 3, Pages: 283-287(2018)
Published： 2018 ，
DOI： 10.15980/j.tzzz.2018.03.015

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[1]张海静,陈星瑞,乐启炽.变频超声半连续铸造ZK60锭坯的组织与力学性能[J].特种铸造及有色合金,2018,38(03):283-287.

Zhang Haijing, Chen Xingrui, Le Qichi. Effects of Varied Ultrasonic Semi-continuous Casting on Microstructure and Mechanical Properties of ZK60 Magnesium Alloy. [J]. Special Casting & Nonferrous Alloys 38(3):283-287(2018)
[1]张海静,陈星瑞,乐启炽.变频超声半连续铸造ZK60锭坯的组织与力学性能[J].特种铸造及有色合金,2018,38(03):283-287. DOI： 10.15980/j.tzzz.2018.03.015.

Zhang Haijing, Chen Xingrui, Le Qichi. Effects of Varied Ultrasonic Semi-continuous Casting on Microstructure and Mechanical Properties of ZK60 Magnesium Alloy. [J]. Special Casting & Nonferrous Alloys 38(3):283-287(2018) DOI： 10.15980/j.tzzz.2018.03.015.

摘要

在半连续铸造255mm的ZK60镁合金锭坯过程中引入了可变频率的超声处理

并与传统的不施加超声处理和施加定频超声半连续铸造锭坯进行了对比

分析了不同处理方案下的ZK60镁合金的组织和力学性能

同时采用数值模拟获得了两种声场下声压随时间的变化规律。结果表明

较传统定频超声场

变频超声场能更大程度地细化晶粒

促进细小、球状的α-Mg的形成

同时可以改变第二相的形貌和分布。经由变频超声场处理后的ZK60镁合金

其心部抗拉强度为280MPa

伸长率为10.9%

相比未施加超声处理的铸锭分别增长了19.1%和78.7%

相比定频超声场处理的铸锭增长了11.6%、28.2%。铸锭不同部位出现的不同细化效果是由于超声衰减所致。变频超声场通过增强异质形核和枝晶破碎的效果来提高细化效果。

Abstract

A varied ultrasonic technology was applied to refine the as-cast microstructure and improve the mechanical properties of a ZK60（Mg-Zn-Zr）alloy with255 mm in semi-continuous casting

which was analyzed comparatively with those of ones without ultrasonic treatment and static frequency ultrasonic semi-continuous casting.The change of acoustic pressure via time in two acoustic field was simulated by numerical method.The varied-frequency acoustic field can promote the formation of smallα-Mg globular grains and change the distribution and morphology ofβphases in the castings

greatly refining grain size in the alloy compared with that of static frequency field.Ultimate tensile strength and elongation of the alloy with varied-frequency field are increased to 280 MPa and 8.9%

respectively

which are 19.1%and78.7% higher than those of ones obtained from billet without ultrasonic treatment and are 11.6% and28.2% higher than that of ones by static-frequency ultrasound treated billets.Different refinement efficiencies appear in different regions of billet

which is attributed to the sound attenuation.The varied-frequency ultrasound can improve refinement effect by enhancing cavitation-enhanced heterogeneous nucleation and dendrite fragmentation effects.