18Ni(200) martensitic age-hardening steel is a kind of ultra-high strength steel with carbon-free or ultra-low carbon Fe-Ni martensite as the matrix, which is hardened by the precipitation of intermetallic compounds through aging treatment. It is a typical martensitic age-hardening steel and also an age-hardening type of plastic mold steel.

Chemical composition（%）

Mechanical properties of 18Ni(200)

Hardness

After solution treatment, 18Ni steel forms ultra-low carbon martensite with a hardness of 28-30HRC. After aging treatment, due to the desolvation and precipitation of various types of intermetallic compounds, aging hardening is achieved, and the hardness can rise to 50HRC.

Other performances

This type of steel still has good toughness and high fracture toughness under conditions of high strength and high hardness. Meanwhile, there is no cold work hardening, the deformation during aging heat treatment is small, the welding performance is good, and the surface can also undergo nitriding treatment, etc.

Heat treatment process

The solution temperature is 815-830℃, and the aging temperature is 480 ± 5℃.

Application field

18Ni(200) martensitic age-hardening steel features high strength and hardness (ultra-high tensile strength, surface hardness 50-54HRC), as well as excellent toughness and plasticity. It is a key material for manufacturing equipment in the aerospace and defense industries and is widely used in fields such as aviation, aerospace, and precision molds. At present, it is widely used at home and abroad as a material for manufacturing high-precision load-bearing parts such as rocket engine casings and high-speed rotating drums of uranium isotope centrifuges. It is also mainly used for manufacturing high-precision, ultra-mirror-finish, complex-cavity, large cross-section, and mass-produced mechanical parts and plastic molds. However, due to its high price, its use is subject to certain restrictions.