AISI 420

General purpose, high hardenability martensitic, 13 Cr type stainless steel with fairly good corrosion resistance.
Normally supplied in the quenched and double tempered condition to 22HRC max hardness (NACE)

Used typically for completion equipment and pressure containing members.
Supplied in the quenched and double tempered condition the material has good strength, reasonable impact properties and good corrosive resistance in standard and C02 environments.
The grade does have limited use in certain environments. It is sensitive to both oxygen and chlorine contamination. It is not recommended for use in high temperature or high chloride environments. Or those containing H2S.

– Product Datasheet

420 PDF