Citation: Ge, Y.; Gou, R.; Yu, M.;
Zhang, C.; Wang, N.; Xu, H. The
Influence of Service Temperature and
Thickness on the Tensile Properties of
Thin T2 Copper Sheets. Materials
2022, 15, 2341.
https://doi.org/10.3390/ma15072341
Academic Editor: Thomas Niendorf
Received: 11 February 2022
Accepted: 17 March 2022
Published: 22 March 2022
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Article
The Influence of Service Temperature and Thickness on the
Tensile Properties of Thin T2 Copper Sheets
Yebao Ge
1,2
, Ruibin Gou
1
, Min Yu
3,
*, Chunyu Zhang
1
, Nian Wang
4
and Hao Xu
1
1
College of Mechanical Engineering, Anhui Science and Technology University, Fengyang 233100, China;
geyebao8080@163.com (Y.G.); gourb@ahstu.edu.cn (R.G.); chunyu_zh@163.com (C.Z.);
xuhao0889@163.com (H.X.)
2
School of Mechanical Engineering, Anhui Polytechnic University, Wuhu 241000, China
3
College of Architecture, Anhui Science and Technology University, Bengbu 233000, China
4
Bengbu Special Equipment Supervision and Inspection Center, Bengbu 233000, China;
wangjun74011@163.com
* Correspondence: yumin-buaa@163.com
Abstract:
Thin T2 copper sheets with nine different thicknesses were employed in uniaxial tensile
tests to investigate the influence of service temperature and thickness on their tensile properties. A
total of 33 groups of tensile samples were separately tested at 20
◦
C, 100
◦
C, 150
◦
C, 200
◦
C, and
250
◦
C to obtain their elongation and their tensile and yield strengths. The change laws of the tensile
properties of the investigated T2 copper were analyzed using different fitting functions. The main
results show that both sheet thickness and temperature have an important influence on the tensile
properties of T2 copper. As the sheet thickness increased, the tensile and yield strengths of the tested
materials first increased rapidly, then decreased sharply, and finally stabilized. As the temperature
increased, the tensile strength increased linearly while the yield strength decreased linearly. The
relationships between the elongation and the sheet thickness and temperature were exponential and
polynomial functions, respectively. T–t–Rm, T–t–Rel, and T–t–
δ
empirical formulas were proposed
and established to predict the tensile properties of the investigated T2 copper sheet, and the predictive
models exhibited solid accuracy.
Keywords: thin T2 copper sheets; tensile properties; service temperature; predict model
1. Introduction
With the rapid development and the improvement of the accuracy requirements in
many science fields, micromechanical systems (MEMS) have developed rapidly, and the
demand for miniaturization of materials is also increasing year by year [
1
–
3
]. Because of
the excellent electrical conductivity and ductility of copper and its alloys, they are widely
used in micro-parts of precision instruments [
4
–
6
]. Unfortunately, when the sheet thickness
reaches the accuracy of millimeters and below, the mechanical properties often show a size
effect which differs from that of conventional materials, and the phenomenon becomes
more obvious with decreasing sheet thickness [
7
,
8
]. Moreover, as the sheet thickness
decreases, the influence of the service temperature on the performance of the material
might become more pronounced and cannot be ignored.
In recent years, many workers have identified the phenomenon that, when the thick-
ness is small, the mechanical properties of copper and its alloys are contrary to those of
conventional materials. It was found that, when the sheet thickness is above the millimeter
scale, the relevant mechanical properties of sheets of materials such as aluminum and steel
deteriorate as the thickness of the sample decreases [
9
–
11
]. When the sheet size is on the
micrometer scale, researchers found that different materials exhibit different mechanical
properties compared to conventional materials. Wu et al. [
12
] studied the mechanical
behavior of 304 stainless steel and found that the yield strength first increased and then
Materials 2022, 15, 2341. https://doi.org/10.3390/ma15072341 https://www.mdpi.com/journal/materials
