Form This specification covers two types of corrosion and heat resistant steel in the form of bars@ wire@ forgings@ and forging stock. Application These products have been used typically for parts on which the amount of machining warrants use of a free-machining grade of steel and requiring hardness within the range of 40 to 50 HRC with corrosion resistance and oxidation resistance up to 1000 ??(538 ??@ but useful at the higher temperatures only when stresses are moderately low@ but usage is not limited to such applications. Certain design and processing procedures may cause these products to become susceptible to stress-corrosion cracking. ARP1110 recommends practices to minimize such conditions. Classification The steel compositions covered by this specification are classified as follows: Type 1 - 13Cr - 0.26Se (0.30 - 0.40C) (420FSe) Type 2 - 13Cr - 0.25S (0.30 - 0.40C) (420F) Unless a specific type is ordered@ either Type 1 or Type 2 may be supplied.