AISI 4340 hydraulic cylinder bar from DATONG HYDRAULIC is produced by 4340 hot rolled steel rod with hard chrome plating and quenched and tempered. The 4340 hydraulic rod is a type of steel with high strength and toughness. It is the most commonly used in the construction industry and hydraulic cylinder field. The 4340 round bar is also called “chrome molybdenum” because it has a higher content of chromium and molybdenum than other types of steel like 4140 or 1045 steel.
The Advantages of DATONG 4340 hydraulic cylinder bar
Annealing
Heat to 800 oC – 850 oC, hold until temperature is uniform throughout the section and cool in furnace.
Induction Hardening
4340 hardened and tempered bar can be further surface hardened by either the flame or induction hardening methods resulting in a case hardness in excess of Rc 50. Parts should be heated as quickly as possible to the austenitic temperature range (830 oC – 860 oC) and required case depth followed by an immediate oil or water quench, depending upon hardness required, workpiece size/shape and quenching arrangements.
Hardening
Heat to 830 oC – 860 oC, hold until temperature is uniform throughout the section, soak for 10 – 15 minutes per 25 mm section, and quench in oil, water, or polymer as required.*Temper immediately while still hand warm.
Nitriding
4340 hardened and tempered cylinder bar can also be successfully nitrit, giving a surface hardness of up to Rc 60. Nitriding is carried out at 490 oC – 530 oC, followed by slow cooling (no quench) reducing the problem of distortion. Parts can therefore be machined to near final size, leaving a grinding allowance only. The tensile strength of the core is usually not affected since the nitriding temperature range is generally
Stress Relieving
Heat to 600 oC – 650 oC, hold until temperature is uniform throughout the section, soak for 1 hour per 25 mm section, and cool in still air.
Tempering
Re-heat to 450 oC – 660 oC as required, hold until temperature is uniform throughout the section, soak for 1 hour per 25 mm of section, and cool in still air.
N.B. Tempering should be avoided if possible within the range 250 oC – 450 oC due to temper brittleness.