What are the application properties of 45MnB alloy steel

What are the application properties of 45MnB alloy steel?
45MnB alloy steel has good hardenability, with a critical hardenability diameter of 17-31mm in oil, higher strength than 40Cr steel, but slightly lower plasticity; its notch sensitivity is greater than 40Cr steel, and notch fatigue strength is poor. The machinability of 45MnB alloy steel is good, and the forging and heat treatment process performance is also good, and the tendency of grain growth, oxidation, decarburization and heat treatment deformation is small when heated.

45MnB alloy steel is used in the quenched and tempered state, generally used to replace 40Cr or 45Cr steel to manufacture medium and small cross-section quenched and tempered parts. Such as gears on machine tools, drilling spindles, tractor turning shafts, cams, spline shafts, crankshafts, idlers, etc.

Weldability of 45MnB alloy steel:
45MnB alloy steel is easy to segregate during crystallization and is more sensitive to crystallization cracks (a kind of thermal cracks). 45MnB alloy steel is easy to crack in the arc crater and the concave part of the weld during welding. The carbon content is high, and it is easy to obtain a hardened structure (martensite structure) sensitive to cold cracks during rapid cooling. When the cooling rate of the superheated zone is large, it is easy to form hard and brittle high-carbon martensite to make the superheated zone brittle.