A new kind of age hardenable martensitic stainless steel with high strength and toughness

Following analysis of typical age hardenable martensitic stainless steels, a new kind of maraging stainless was developed. The new maraging stainless steel showed high strength, ultimate tensile strength (UTS)= 1670 MPa, high toughness, K-IC=83.9 MPa ml(1/2) and hardness as high as 478 HV in the age hardened condition. Microstructural study with an optical and transmission electron microscope revealed the typical microstructure of age hardenable stainless steel containing lath martensite and precipitates. Ti,Ni precipitates were identified by transmission electron microscopy, which were responsible for the increase in mechanical properties after age hardening. The results of natural salt spray test showed that the corrosion resistance of new maraging stainless steel approached to the corrosion resistance of 304L stainless steel.