The hardness of 40Cr steel
40Cr steel material widely be used in the machine-building industry. 40Cr is a standard grade of GB. After quenching and tempering, it will get great comprehensive mechanical property and great low-temperature impact toughness. And its hardenability is good. After the oil quenching, the fatigue limit will be higher. But the fittings with complex shape is easy to get crack after the water quenching. It is also suitable for cyaniding and high-frequency quenching beside Q+T. Its machinability also is good, if the hardness is 174-229 HB, the machinability is 60%.
40Cr steel material is a good choice for medium type plastic mold. It belongs to mild Q+T steel and cold heading mold steel. Also, the price is not high, easy to be processed. After the right heat treatment, it will get good toughness, plasticity and wear resistance. Tempering at the range of 550-570℃, it will get the best mechanical property. The equivalent steel grade of 40Cr is 40MnB, 45 MnB, 35SiMn, 42SiMn, 40MnVB, 42MnV, 40MnMoB, 40MnWB and etc.
What is 40Cr Steel Material Used for?
It is one of the most popular steel grades in the industry. After Q+T heat treatment, it usually is used to make parts. Such as the gears of machine tools, shaft, worm, cylinder shaft and etc. If it is through quenching and tempering; high-frequency quenching, it will be good choice for fittings with high hardness and wear resistance. For example, cylinder rod, cylinder honed barrel, wheel gear, shaft, principal axis, crankshaft, arbor, inlet valve, bolt and etc.
The carbon content of 40Cr is lower than 45# steel. At the condition of hot-rolled, their mechanical property is almost the same.