Improvement of S355J2 Steel Mechanical Properties by Heat Treatment

abstract

en

Steel grade S355J2 (1.0577) is standard carbon steel which is commonly used in building engineering. The Heat Transfer and Fluid Flow Laboratory is equipped by a testing device called Karusel. It enables to simulate heat treatment processes. It is equipped by two different nozzle sizes cooling headers so it is possible to simulate cooling line with hard and soft cooling regimes (hard in high temperature area and soft in low temperature area). First, an austenitic steel plate was used to obtain heat transfer coefficient. It was used for simulations to predict the cooling regime for full scale experiment. S355J2 carbon steel samples were embedded by thermocouples to measure the temperature drop in the material. Dimensions of these samples were 100 x 100 mm and the thickness of them was 5, 12 and 20 mm. The main idea of this research was to improve the standard material properties. The initial temperature of samples was 930 °C and it was hold for more than 10 minutes. Then each sample was cooled down to the target equalization temperature of 600 °C in the whole body. This means that cooling was stopped when the surface temperature was lower than 600 °C and body center temperature was higher than 600 °C. Mechanical properties of heat treated samples were tested. A material hardness was significantly improved up to 10 mm from the sprayed surface. Two samples were chosen for tensile and Charpy pendulum impact tests. The strength was improved up to 820 MPa. The impact energy was improved four times up to 200 J.

Steel grade S355J2 (1.0577) is standard carbon steel which is commonly used in building engineering. The Heat Transfer and Fluid Flow Laboratory is equipped by a testing device called Karusel. It enables to simulate heat treatment processes. It is equipped by two different nozzle sizes cooling headers so it is possible to simulate cooling line with hard and soft cooling regimes (hard in high temperature area and soft in low temperature area). First, an austenitic steel plate was used to obtain heat transfer coefficient. It was used for simulations to predict the cooling regime for full scale experiment. S355J2 carbon steel samples were embedded by thermocouples to measure the temperature drop in the material. Dimensions of these samples were 100 x 100 mm and the thickness of them was 5, 12 and 20 mm. The main idea of this research was to improve the standard material properties. The initial temperature of samples was 930 °C and it was hold for more than 10 minutes. Then each sample was cooled down to the target equalization temperature of 600 °C in the whole body. This means that cooling was stopped when the surface temperature was lower than 600 °C and body center temperature was higher than 600 °C. Mechanical properties of heat treated samples were tested. A material hardness was significantly improved up to 10 mm from the sprayed surface. Two samples were chosen for tensile and Charpy pendulum impact tests. The strength was improved up to 820 MPa. The impact energy was improved four times up to 200 J.

heat transfer, heat treatment, S355J2, cooling, heat transfer coefficient, water, spray cooling, heat treatment

28.09.2016

Inštitut za kovinske materiale in tehnologije

Ljubljana, Slovenia

978-961-94088-0-3

24th INTERNATIONAL CONFERENCE ON MATERIALSAND TECHNOLOGY

84–84

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