Scatter Characteristics of Tensile Strength of T4/T6-Treated Low Pressure Die Casting AC4A Aluminum Alloys

Zou Chun; Zhao Haidong; He Shao; Hu Zhiwei

doi:10.15980/j.tzzz.2014.04.025

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Scatter Characteristics of Tensile Strength of T4/T6-Treated Low Pressure Die Casting AC4A Aluminum Alloys
Vol. 34, Issue 4, Pages: 401-405(2014)
Published： 2014 ，
DOI： 10.15980/j.tzzz.2014.04.025

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[1]邹纯,赵海东,何韶,胡志伟.低压铸造AC4A合金T4/T6态抗拉强度分散性研究[J].特种铸造及有色合金,2014,34(04):401-405.

Zou Chun, Zhao Haidong, He Shao, et al. Scatter Characteristics of Tensile Strength of T4/T6-Treated Low Pressure Die Casting AC4A Aluminum Alloys. [J]. Special Casting & Nonferrous Alloys 34(4):401-405(2014)
[1]邹纯,赵海东,何韶,胡志伟.低压铸造AC4A合金T4/T6态抗拉强度分散性研究[J].特种铸造及有色合金,2014,34(04):401-405. DOI： 10.15980/j.tzzz.2014.04.025.

Zou Chun, Zhao Haidong, He Shao, et al. Scatter Characteristics of Tensile Strength of T4/T6-Treated Low Pressure Die Casting AC4A Aluminum Alloys. [J]. Special Casting & Nonferrous Alloys 34(4):401-405(2014) DOI： 10.15980/j.tzzz.2014.04.025.

摘要

对低压铸造的AC4A合金发动机缸盖进行T4/T6热处理并取样观察微观组织和测试力学性能

使用配备能谱仪的扫描电镜分析了拉伸断口形貌

鉴定了断口表面夹杂物等铸造缺陷;对力学性能数据进行了Weibull统计分析

研究了不同时效温度和时间条件下抗拉强度数据的分散性。结果表明

T4热处理后仍有相当多的共晶Si粒子呈长针状

AC4A合金拉伸试样均呈现脆性断裂

塑性较差;进行T4+175℃×4h的T6热处理的AC4A合金的抗拉强度Weibull模数达到32.3729

明显高于其他两组T6热处理的试样

表明其数据分散性最小

性能稳定;进行T4+175℃×4h的T6热处理的AC4A合金的平均抗拉强度较高

但特征值略低于T4+155℃×10h的T6热处理后的AC4A合金。

Abstract

Microstructure and tensile properties of specimens directly machined from the practical low pressure die casting AC4Aalloy engine cylinder heads with different heat treatments（T4/T6）were analyzed.After tensile testing

defects in the fracture surfaces were observed and analyzed by scanning electron microscope（SEM）attached with energy-dispersive X-ray spectroscopy（EDX）.In addition

Weibull statistical analysis method was applied to identify the scatter of tensile strength of the parts with different aging temperatures and time.The results indicate that the silicon particles in the parts after T4 heat treatment are characterized by long acicular shapes

and the specimens at both T4and T6status belong to brittle fracture mode.The T6-175℃×4h（artificially aged for 4hat 175℃）treated alloy has a maximum Weibull modulus（32.3729）for ultimate tensile strength（UTS）

which is obviously higher than those of the other specimens

meaning the minimum scatter of the data and desirable stablity

while the characteristic tensile strength of the T6-175 ℃×4htreated alloy is slightly below that of T6-155 ℃×10htreated alloy.