Effects of Heating Temperature and Cooling Method on the Quenching Hardness of Steel
Abstract
This paper mainly discusses the effects of heating temperature and cooling method on the quenching hardness of steel. The manufacture of steel parts is inseparable from the heating and cooling process, and the quenching process is the main means of heat treatment. Temperature control and cooling method are the key factors affecting the quenching effect of metal parts. In order to test the relationship between heating temperature and cooling method and quench hardneess, we select some appropriate common steels, and carry out quenching tests at different heating temperatures and cooling speeds, and analyze the different effects of different heating temperatures and cooling methods on the quenching hardness of steel.
Keywords: Quenching hardneess; Heating temperature; Cooling method; Steel
1 Introduction
Quenching is an important process in the heat treatment of steel parts, which increases the history of the material and increases its mechanical properties. Quenching and tempering can also improve the fatigue strength, tensile strength and yield strength of steel parts, so as to improve the overall quality of the steel parts. The quenching treatment of steel is mainly to heat the steel generally to a certain temperature, and then cool it quickly to obtain martensite. However, due to the difference of steel performance and quenching cooling medium, the target temperature of heat preservation is not the same, and the cooling speed and temperature of quenching also have a certain influence on the quenching hardness of steel. Therefore, it is necessary to carry out a certain amount of actual experience to find the most appropriate temperature for different steel and cooling speed, so that to obtain the maximum quenching hardness.
2 Experimental methods
2.1 Materials
The materials used in this experiment come from the same supplier, and the chemical composition of the steel is as follows: C0.15%, Mn0.36%, Si0.35%, P0.02%, S0.02%.
2.2 Experimental device
According to the different steel properties and quenching cooling medium, the heating device of this experiment uses two kinds of heating equipment, namely water-cooled simulation vacuum furnace and electric-resistance heating furnace.
2.3 Experimental process
In order to get the best quenching hardness of stainless steel, the experimental specimen is cut into plane size of 20×20mm, and the initial heat preservation temperature is different according to the steel type. Then the specimen is quickly cooled at different speeds, and the cooling speed is from 0.2-2m/s. And then put it into the quenching cooling medium immediately, finally get a certain hardness and then compare.
3 Results and discussion
3.1 The different heating temperatures and cooling methods affect the quenching hardness of the steel
Fig. 1 shows the relationship between the quenching hardness and the steel heating temperature. It can be seen from the figure that with the increase of the heating temperature, the quenching hardness of the steel increases significantly, and its quenching hardness can reach 56HRC or higher at 880-920℃. It can be seen that when the heating temperature of the steel is high, the quenching hardness of the steel becomes higher with the increase of temperature.
Fig. 2 shows the relationship between the quenching hardness and cooling speed. It can be seen that the quenching performance increases with the increase of cooling speed, and the quenching hardness of steel can exceed 60HRC at the high fencing speed of 1.3~1.5m/s. Moreover, it can be seen from Fig. 2 that when the cooling speed is less than 1.3m/s, the quenching hardness of steel is slightly increased with the cooling speed. That is to say, the higher the cooling speed, the better the quenching effect.
3.2 Conclusion
The results of the paper show that the heating temperature and cooling method play an important role in the quenching hardness of steel. With the increase of heating temperature, the quenching hardness of steel increases, and the higher the quenching speed is, the higher the quenching hardness is. For different steels, the appropriate heating temperature and cooling method are needed to obtain the best quenching parameters, so as to improve the overall performance of the steel parts.
4 Recommendations
Based on the conclusion of the above experiments, it can be concluded that for different steel types, appropriate heating temperatures and cooling methods are needed to get the best quenching effect. In actual production, it is necessary to consider not only the heating temperature, but also the appropriate cooling speed, so as to obtain the best quenching effect of steel parts.
