Technical indicators:

material	38 CrMoA1A(JIS SACM645) 42 CrMo(AISI 4140)	Hardness of nitride layer	HV≥900
		Thickness of nitride layer	0.5-0.8mm
diameter	Φ12-Φ300mm	Surface roughness	Ra0.4μm
Aspect ratio	L/D=10-56	Hardness of chrome plating layer	850 HV
Nitride brittleness	<Level 2	Depth of chrome plating layer	0.03-0.08mm

Material: Surface tungsten carbide ultrasonic integral spray welding to improve the wear resistance of the screw.
Material processing: heat treatment, nitriding treatment, electroplating hard chromium layer, high-frequency quenching, spraying bimetallic alloy layer, vacuum quenching, can greatly improve the service life of the three small parts.
　　
While emphasizing the maintenance of high-performance development, we have introduced a series of modern facilities and continuously improved our quality control system. Adhering to the service philosophy of serving customers, we take continuously exceeding their expectations as our pursuit.