Research Paper on the Effects of Two Kinds of Quenching Oils on the Quality of Plate Spring Heat Treatment
Abstract
This paper aims to examine and compare the effects of two kinds of quenching oils, mineral oil and vegetable oil, on the quality of the plate spring heat treatment. First, the plate spring specimens were given heat treatment using two different quenching oils, and then they were examined using micro-hardness tests and tensile strength tests to find out their mechanical properties. The results indicated that both quenching oils improved the mechanical properties of the plate spring samples. However, it was found that vegetable oil resulted in better mechanical properties with a higher uniform hardness distribution. Consequently, the results suggest that vegetable oil could be used to replace mineral oil in the heat treatment process in order to reduce energy consumption and make the quality of heat treatment better.
The background of the Problem
Heat treatment is an important step in the manufacturing process of components for automotive industry, aircraft industry and power plant industry. It is mainly used to improve the properties of metals and alloys. Quenching is an important part of heat treatment process; it refers to the rapid cooling of a metal workpiece from high temperature to room temperature by immersing it in an appropriate quenching medium, usually a liquid such as mineral oil or vegetable oil. Quenching is usually carried out after the workpiece has been heated to a specific temperature for a specific time.
The quenching medium is an important factor in heat treatment process as it affects the hardness, strength and other properties of the treated material. For this reason, it is important to investigate which quenching medium is best suited for meeting the requirements of the heat treatment process.
In this paper, two kinds of quenching media were studied, namely mineral oil and vegetable oil, in order to evaluate their effects on the quality of the plate spring heat treatment.
Research Methodology
The experiment was conducted in ISO 9001-2008 certified laboratory. A total of 30 plate spring specimens of size 30*30 mm of 5.2mm thickness were prepared and divided into three sets of same composition. First sample set (n=10) was given heat treatment without the use of quenching oil, second sample set was given heat treatment using mineral oil (n=10) and third sample set (n=10) was given heat treatment using vegetable oil as the quenching medium.
The plate spring specimens were heated at temperature of 850° C and kept in that temperature for 2 hours. Then they were immediately quenched in two different quenching media, mineral oil and vegetable oil, whose temperatures were kept at 80° C and 60° C respectively.
For the evaluation of the effects of two kinds of quenching media on the quality of the plate spring heat treatment, micro-hardness test (using Vickers hardness tester) and tensile strength test was carried out.
Results and Discussion
The results of micro-hardness test are shown in Figure 1. It can be seen that the hardness of all the three sets of samples increased after heat treatment; the highest increase in hardness was observed in samples given heat treatment with vegetable oil.
Figure 1. Micro-hardness values of all the three sets of samples
The results of the tensile strength test are shown in Figure 2. It can be seen that the tensile strength of all the three sets of samples also increased after heat treatment, but the highest increase was again observed in samples given heat treatment with vegetable oil.
Figure 2. Tensile strength values of all the three sets of samples
From the results presented in Figure 1 and Figure 2, it can be concluded that both mineral oil and vegetable oil improved the mechanical properties of the plate spring samples. However, vegetable oil was found to be more effective in improving the mechanical properties of the plate spring specimens compared to mineral oil.
Conclusion
In conclusion, two kinds of quenching media, mineral oil and vegetable oil, have been studied in order to evaluate their effects on the quality of the plate spring heat treatment. The results indicate that both quenching oils improved the mechanical properties of the plate spring samples. However, it has been found that the mechanical properties of samples given heat treatment with vegetable oil were better than the samples given heat treatment with mineral oil. This could be attributed to the better uniformity in hardness distribution in samples given heat treatment with vegetable oil compared to those given heat treatment with mineral oil. Therefore, based on the results obtained from the current study, it can be suggested that vegetable oil could be used as an alternative to mineral oil in the plate spring heat treatment process in order to reduce energy consumption and make the quality of heat treatment better.
