Abstract

This paper wants to know the effect of bending radius on the distribution of hardness, grain distribution and microstructure on the surface area of tensile stress and compressive stress after bending, quenching and tempering. Material testing helps determine and analyze material quality. The research was conducted on the bending of Hot Rolled Plate Steel material with a radius of 50 mm, 55 mm, 60 mm, 65 mm and 70 mm with a measurement distance of 1 mm, 2 mm and 3 mm, the highest value was obtained at a radius of 55 mm with a measurement distance of 1 mm. After getting the quench-temper treatment with a holding time of 30 minutes, the value of 498 HV was obtained at a radius of 70 mm with a measurement distance of 2 mm. Hardness test was performed using the austenite temperature of 900 °С, microstructure test results obtained finer grains in the compression area r=2.173 µm and in the tensile area r=2.34 µm. This observation aims to determine the microstructure of the material undergoing a heat treatment process at a temperature of 900 °С with a holding time of 30 minutes using water cooling media. The results of the observation of the microstructure of the test specimens before the quench-temper process showed that the structure of ferrite was more abundant than perlite, but after the quench-tempering process the results showed that there was more perlite than ferrite due to the presence of austenite. The treatment on the transformation of the Ar3 line causes the hardness to change the shape of the martensite microstructure into steel while the thickness of the carburizing layer increases with the increase in the carbonization temperature on the surface of the quenched specimen, resulting in the formation of martensite and residual austenite causing the coating to become hard.

Highlights

  • Many researchers study the impact of alloy composition and heat treatment on the mechanical properties of steel, such as macro and micro inspection

  • This material has the advantage of being strong against impact, toughness and the ability to be hardened better when compared to chrome steel [14]. This is indicated by the presence of chemical elements in Hot Rolled Plate Steel (HRPS) with the following contents: elemental silicium shows a value of 0.32985 % indicating the silicon content is less than 0.4 %, which has the effect of decreasing tensile stress and increasing critical cooling speed, manganese of 1.41218 %, which has good melting process properties, chrome of 0.55029 % serves to increase tensile strength and plasticity, increase hardness, increase corrosion resistance and high temperature resistance, molybdenum value of 0.19303 % indicates good strength and toughness

  • The results showed that the quench and tempering treatment changed the hardness at a bending radius of 70 mm, which is up to 498 HV, a higher VHN value in QT-HRP compared to T-HRP, which shows an increase in steel ductility

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Summary

Introduction

Many researchers study the impact of alloy composition and heat treatment on the mechanical properties of steel, such as macro and micro inspection. The results showed that increasing the quenching temperature could increase the grain size of austenite (dr), martensite package (dp), and beam (db). Toughness is another important property for armored materials having high kinetic energy upon dynamic attack of projectiles, and armored steel can still be developed [6,7,8]. Armor steel has high strength and hardness to protect conveyances, vehicles, objects, or individuals from direct pressure projectiles, but armor steel in general is still not able to meet the needs for a tank body from the level of hardness and ductility so it is not easy to crack if it gets impact energy [9]. Several studies have shown that the requirements of armored steel as a tank body material are various mechanical properties such as the range

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