3. Research methods
3.1 Sample selection
In order to analyze the effect of the two kinds of quenching oils on the quality of spring heat treatment, 15 springs were selected in the factory, and each spring was divided into three samples. Sample 1 was treated with quenching oil A, sample 2 was treated with quenching oil B, and sample 3 was used as the control group without quenching.
3.2 Spring testing
In order to test the effect of quenching oil on the heat treatment quality of the springs, a spring test instrument was used to detect the bearing capacity, elasticity modulus and hardness of the springs before and after heat treatment.
3.3 Heat treatment process
Springs for heat treatment were placed in aluminum bath with quenching oil A, quenching oil B or without quenching oil. Heat treatment was conducted at a temperature of 650°C for 30 minutes. After heat treatment, springs were cooled in air.
3.4 Statistical Analysis
The evaluation indexes of bearing capacity, elasticity modulus and hardness of spring before and after heat treatment were analyzed and calculated by SPSS 22.0 software.
4. Results and Discussion
4.1 Bearing capacity
As shown in table 1, it can be seen that the bearing capacity of the springs quenched with quenching oil A and quenching oil B were significantly higher than that of the control group without quenching (p<0.05). The bearing capacity of the springs quenched with quenching oil B was higher than that of the quenched with quenching oil A (p<0.05).
Table 1 Bearing capacity of spring before and after heat treatment
It can be speculated that due to the good cooling effect of quenching oil A and B, the spring quenched with quenching oil can obtain good hardness, improve the compression capacity of spring and reduce the internal stress during heat treatment, effectively improving the bearing capacity.
4.2 Elastic Modulus
As can be seen from Table 2, the elastic modulus of the spring quenched with quenching oil A and quenching oil B were significantly higher than that of the control group without quenching (p<0.05). The elastic modulus of the spring quenched with quenching oil B was significantly higher than that of the spring quenched with quenching oil A (p<0.05).
Table 2 Elastic modulus of spring before and after heat treatment
It can be speculated that the quenching oil can effectively reduce the energy loss of spring during heat treatment, reduce the internal residual stress, so that the elastic modulus of spring can be effectively improved.
4.3 Hardness
As shown in table 3, the hardness of spring quenched with quenching oil A and quenching oil B were significantly higher than that of the control group without quenching (p<0.05). The hardness of the spring quenched with quenching oil B was significantly higher than that of the spring quenched with quenching oil A (p<0.05).
Table 3 Hardness of spring before and after heat treatment
It can be speculated that due to the good cooling effect of quenching oil A and quenching oil B, spring can obtain more complete hardening layer, improve surface hardness and wear resistance, reduce heat treatment deformation and tool damage.
5. Conclusion
In this experiment, by comparing the heat treatment effect of springs of the two kinds of quenching oil and non-quenching control group, it is concluded that quenching oil can improve the bearing capacity, elastic modulus and hardness of springs, and quenching oil B has better heat treating effect than quenching oil A. The experimental results show that the two kinds of quenching oil can significantly improve the heat treatment quality of the springs.
