Journal of Materials Science and Engineering B 8 (3-4) (2018) 45-48 doi: 10.17265/2161-6221/2018.3-4.001 Effect of High Pressure Heat Treatment on Microstructure and Compressive Properties of Low Carbon Steel Meng Deliang College of Civil Engineering and Mechanics, Yanshan University, Qin Huang Dao 066004, China Abstract: The effect of high pressure heat treatment on microstructure and compressive properties of low carbon steel were investigated by optical microscope, transmission electron microscope, hardness tester and compression test methods. The results show that martensite appears in low carbon steel at 1-5GPa GPa and 950 °C for 15 minutes treatment, high pressure heat treatment can improve the hardness and compressive properties of the steel, the yield strength of the steel increases with increasing pressure, and its compressive properties are better than that treated under normal pressure quenching. Key words: Low carbon steel, high pressure heat treatment, microstructure, compressive properties. 1. Introduction Low carbon steel is a common steel for carbon components, it has been widely used in various fields of modern industry. However, the application of low carbon steel is limited largely due to its lower strength and compressive deformation resistance. Therefore, researchers have paid much attention to the performance potential of low carbon steel [1, 2]. It is well known that high pressure heat treatment can improve the microstructure and mechanical properties of metal materials [3-5]. But there was still no clear understanding of compressive properties of low carbon steel after high pressure heat treatment. For that reason, the microstructure and compressive properties of low carbon steel before and after high pressure heat treatment are observed and tested, and the effect of high pressure heat treatment on microstructure and compressive properties of the steel were discussed. This will provide basis for giving full play to the performance potential of low carbon steel. 2. Experiments Corresponding author: Meng Deliang, senior engineer, research field: metallic materials. The experimental material is hot-rolled low carbon steel, its chemical composition (mass fraction, %) is: 0.19C, 0.45Mn 0.29Si, 0.031P, 0.026S, and the samples’ size is Ф6 mm × 10 mm. High heat treatment was done on CS-IB type six-anvil high-pressure equipment under high pressure which is 1 GPa, 3 GPa and 5 GPa, after heating at 950 °C and lasting for 15 minutes, shutting off power and cooling to room temperature on holding up pressure. Some low carbon steel samples were also subjected to normal pressure quenching in the KL-13D type resistance furnace, the process is heated to 950 °C for 15 min, and then cooling in 10% salt solution. The room temperature compression test was carried out on the WDW3100 electronic universal testing machine, the compression speed is 1 mm/min, the hardness of the samples before and after treatment was tested by HR-150A hardness tester. The microstructure of the samples was analyzed by means of Axiovert200MAT optical microscope and H-800 transmission electron microscope. 3. Results and Discussion 3.1 Microstructure Fig. 1 shows the microstructure of low carbon steel D DAVID PUBLISHING
4
Embed
Effect of High Pressure Heat Treatment on Microstructure and ...€¦ · Effect of High Pressure Heat Treatment on Microstructure and Compressive Properties of Low Carbon Steel Meng
This document is posted to help you gain knowledge. Please leave a comment to let me know what you think about it! Share it to your friends and learn new things together.
Transcript
Journal of Materials Science and Engineering B 8 (3-4) (2018) 45-48 doi: 10.17265/2161-6221/2018.3-4.001
Effect of High Pressure Heat Treatment on
Microstructure and Compressive Properties of Low
Carbon Steel
Meng Deliang
College of Civil Engineering and Mechanics, Yanshan University, Qin Huang Dao 066004, China
Abstract: The effect of high pressure heat treatment on microstructure and compressive properties of low carbon steel were investigated by optical microscope, transmission electron microscope, hardness tester and compression test methods. The results show that martensite appears in low carbon steel at 1-5GPa GPa and 950 °C for 15 minutes treatment, high pressure heat treatment can improve the hardness and compressive properties of the steel, the yield strength of the steel increases with increasing pressure, and its compressive properties are better than that treated under normal pressure quenching. Key words: Low carbon steel, high pressure heat treatment, microstructure, compressive properties.
1. Introduction
Low carbon steel is a common steel for carbon
components, it has been widely used in various fields
of modern industry. However, the application of low
carbon steel is limited largely due to its lower strength
and compressive deformation resistance. Therefore,
researchers have paid much attention to the
performance potential of low carbon steel [1, 2]. It is
well known that high pressure heat treatment can
improve the microstructure and mechanical properties
of metal materials [3-5]. But there was still no clear
understanding of compressive properties of low
carbon steel after high pressure heat treatment. For
that reason, the microstructure and compressive
properties of low carbon steel before and after high
pressure heat treatment are observed and tested, and
the effect of high pressure heat treatment on
microstructure and compressive properties of the steel
were discussed. This will provide basis for giving full
play to the performance potential of low carbon steel.
Fig. 1 Microstructures of low carbon steel at different states.
(a) hot rolling (b) 3 GPa treatment
Fig. 2 TEM images of low carbon steel before and after cryogenic treatment.
(a)
0.5 μm
(b)
0.5 μm
40 μm
(c)
40 μm
(d)
40 μm
(e)
40 μm
(b)(a)
40 μm
Effect of High Pressure Heat Treatment on Microstructure and Compressive Properties of Low Carbon Steel
47
Table 1 The hardness of low carbon steel at different states.
Specimen Hot rolling Normal pressure quenching 1 GPa 3 GPa 5 GPa
Hardness (HRC) 12 35 45 46 47
Fig. 3 Stress-strain curves of low carbon steel at different states.
the hardness value of low carbon steel after 1~5 GPa
pressure treatment has little change, the hardness
value of the steel is HRC45~47, higher than normal
pressure quenched. When the pressure is 3 GPa, its
value is HRC36, and increased by 31.43% than that of
the steel at pressure quenching.
Fig. 3 shows stress-strain curve of low carbon steel
under different conditions. It can be seen that obvious
plastic deformation stage appeared in all specimens
under static compression. High pressure heat
treatment can improve the compression performance
of the steel, the compressive yield strength increases
with the increase of pressure. As you can see from Fig.
2 that the change of stress-strain curve trend of high
heat treatment and quenching treatment is similar
trend, however, the yield strength of the steel after
high pressure heat treatment is higher than that of
normal quenching. This indicates that the compressive
property of low carbon steel after high pressure heat
treatment is better than that of normal quenching. It is
known from the experimental results that the
compressive yield strength of the steel after 5 GPa
pressure heat treatment is 1,846.92 Mpa, and
increased by 665.21% and by 29.01% than that of the
steel at hot rolling and normal pressure quenching,
respectively.
Because of the existence of lath martensite in low
carbon steel after high pressure heat treatment, at the
same time, high pressure causes lattice distortion, it
causes the hardness and strength of the steel to
increase, and the compression ability of steel is
improved. Normally, the yield strength of metallic
materials increases with decreasing grain size [7], and
the martensite obtained by high pressure heat
treatment of low carbon steel is smaller than that of
normal pressure quenching, the martensitic lath
decreases with the increase of pressure. Therefore, the
yield strength of low carbon steel after high pressure
heat treatment is higher than that of normal quenching,
and the yield strength also increases with the increase
of pressure.
4. Conclusions
(1) Lath martensite is formed in low carbon steel
after high pressure heat treatment, its hardness and
compressive properties are improved, and the greater
the pressure, the smaller the martensite, the better the
compressive property.
(2) The compressive properties of low carbon steel
after 1~5 GPa pressure and at 950 °C for 15 minutes
treatment are better than that of normal quenching, the
compressive yield strength of the steel after 5 GPa
pressure heat treatment is 1,846.92 Mpa, and
increased by 665.21% and by 29.01% than that of the
steel at hot rolling and normal pressure quenching,
respectively.
References
[1] Hu, Z. P., and Zhang, H. M. 2010. “A Study on the Tensile Test of Low Carbon Steel at Thickness Direction.” Journal of Plasticity Engineering 17 (2): 120-2.
Strain%
Str
ess/
MP
a
5GPa
0 3 6 9 12 150
600
1200
1800
2400
3000
hot rolling
normal
1GPa
3GPa
Effect of High Pressure Heat Treatment on Microstructure and Compressive Properties of Low Carbon Steel
48
[2] Zhao, J., Zhuo, H. Y., Wang, Z, et al. 2011. “Preparation of In-Situ Composite Q235 Plate with Ultra-High Strength.” Hot Working Technology 40 (2): 89-91.
[3] Yue, X. J., Duan, W. Y., Xue Y., and Yan, L. U. 2012. “Effect of High-Pressure Solution and Atmospheric-Pressure Aging Treatment on Microstructure and Compressive Properties of AM60 Alloy.” Hot Working Technology 41 (2): 195-7.
[4] Zhao, J., Liu, L., Yang, J. R., Peng, G., Liu, J., Zhang, R., et al. 2008. “Effects of High Pressure on the Microstructure and Hardness of a Cu-Zn Alloy.” Rare Metals 27 (5): 541-4.
[5] Wu, L. L., Liu, L., Liu, J. H., and Zhang, R. 2012.
“Effects of High Pressure Heat Treatment on Microstructure and Micro-mechanical Properties of Cu77.96Al22.04 Alloy.” Matterials Transactions 53 (3): 504-7.
[6] Wang, H. Y., Liu, J. H., Peng, G. R., and Wang, W. B. 2010. “Effects of High-Pressure Heat Treatment on the Solid-State Phase Transformation and Microstructures of Cu61.13Zn33.94Al4.93 Alloys.” Chinese Physics B 19 (9): 096203-1-6.
[7] Wu, X. H., Li, J., Guo, W. Y., Zhang, K., and Ya-Ting, W. U. 2011. “Effect of Quenching Heating Rate on Microstructure and Mechanical Properties of the Cold Rolled 980 MPa Dual Phase Steel.” Materials for Mechanical Engineering 35 (5): 27-31.