An Investigation of the Simultaneous Effect of Shot Peening and Baking on the Tensile Behavior of 50crv4 Alloy Steel
Subject Areas :
Malihe
Ghasemzade
1
(Assistant Professor, Department of Materials Engineering, NazarAbad, Karaj Branch, Islamic Azad University, Karaj, Iran.)
Hamid
Nazemi
2
(Assistant Professor, Department of Materials and Mechanical Engineering, Mobarakeh Branch, Islamic Azad University, Isfahan, Iran)
Keywords: Shot Peening, Hydrogen Embrittlement, 50CrV4 steel, Baking,
Abstract :
In this paper, 50CrV4 steel wire with a diameter of 4 mm were subjected to pure Zn electroplating. The effect of shot peening before and baking after electroplating on tensile performance of steel was investigated. Bombardment was done before plating for 20 minutes with shots 0.5 mm and 58 RC. Baking was performeIn this paper, 50CrV4 steel wire with a diameter of 4 mm were subjected to pure Zn electroplating. The effect of shot peening before and baking after electroplating on tensile performance of steel was investigated. Bombardment was done before plating for 20 minutes with shots 0.5 mm and 58 RC. Baking was performed after plating for 24 hours at 200°C. Finally, the samples were subjected to slow strain rate test, microhardness test and SEM imaging. The results showed that the effect of baking on improving the mechanical life of the sample under tension alone is greater than the shot peening. The mean time to failure of plated and baked samples was 2.5 hours, but for shot and plated samples was 2.1 hours. The simultaneous effect of pre-plating shot peening and post-plating baking led to further improvement of the tensile performance of the wire and the mean failure time reached 3.55 hours in the slow strain rate test. The embrittlement susceptibility index is now reduced from 0.76 for only plated samples to 0.13 for shot peened and baked samples, which shows a very good improvement. The effect of shot peening on the tensile properties of steel can be attributed to the formation of a residual compressive stress layer on the substrate surface, which leads to a reduction in the growth rate of microcracks due to tensile stresses under working conditions. The results also showed that due to the baking, continuous microcracks are created in the coating / substrate interface, which provide suitable paths for hydrogen to leave the substrate. after plating for 24 hours at 200°C. Finally, the samples were subjected to slow strain rate test, microhardness test and SEM imaging. The results showed that the effect of baking on improving the mechanical life of the sample under tension alone is greater than the shot peening. The mean time to failure of plated and baked samples was 2.5 hours, but for shot and plated samples was 2.1 hours. The simultaneous effect of pre-plating shot peening and post-plating baking led to further improvement of the tensile performance of the wire and the mean failure time reached 3.55 hours in the slow strain rate test. The embrittlement susceptibility index is now reduced from 0.76 for only plated samples to 0.13 for shot peened and baked samples, which shows a very good improvement. The effect of shot peening on the tensile properties of steel can be attributed to the formation of a residual compressive stress layer on the substrate surface, which leads to a reduction in the growth rate of microcracks due to tensile stresses under working conditions.
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