Most of the shovel teeth of roadheader work in the environment of high impact, high wear and high hardness, so the materials must have high impact toughness and high hardness. Bainitic steel has good comprehensive mechanical properties and relatively low cost, which has attracted much attention in recent years. However, bainite isothermal quenching is easy to deform ultra light and narrow series castings, and it is very difficult to reshape. This is the main problem faced by the application of bainite quenching in production.
How to select alloy elements and adjust heat treatment process parameters according to working conditions is the key to ensure the service performance of materials.
(1) with the increase of carbon content, the toughness of the test steel decreases and the hardness increases.
(2) With the increase of Si content, the amount of austenite increases, the toughness increases obviously, and the hardness decreases slightly.
(3) the effect of isothermal temperature on material properties varies according to the content of carbon and silicon. When C is 0.48%, the comprehensive mechanical properties at 310 ℃ are relatively good; When C is 0.43%, the comprehensive mechanical properties at 270 ℃ are relatively good; When C is 0.38%, the comprehensive mechanical properties at 340 ℃ are relatively good.
(4) the test steel can obtain different hardness and toughness indexes by adjusting different chemical composition and heat treatment process parameters according to the service conditions of castings, so as to meet the mechanical property requirements of products.