Lambobi biyu a farkon karfe suna nuna carbon abun ciki na karfe, wanda aka nuna a cikin kashi biyu na matsakaicin carbon abun ciki, kamar 40Cr.

② Babban alloy abubuwa a karfe, ban da mutum micro alloy abubuwa, yawanci aka nuna a 'yan kashi. Lokacin da matsakaicin gami abun ciki <1.5%, karfe lambobi a yau da kullun alama kawai abu alama, ba alama abun ciki, amma a

A cikin yanayi na musamman masu rikitarwa, za a iya yin alama da lambar '1' bayan alamar abu, misali lambar karfe '12CrMoV' da '12Cr1MoV', wanda ke da chromium na farko na 0.4-0.6%, kuma na ƙarshe

0.9-1.2%, sauran abubuwa duk iri ɗaya. Lokacin da alloy abubuwa matsakaicin abun ciki ≥1.5%, ≥2.5%, ≥3.5%... a bayan abubuwa alama ya kamata a nuna abun ciki, za a iya nuna daidai a matsayin 2, 3,

4 ... da sauransu. Misali, 18Cr2Ni4WA.

② Vanadium V, titanium Ti, aluminum AL, boron B, rare earth RE da sauran kayan haɗin gwiwa a cikin karfe, duk da haka suna da ƙananan kayan haɗin gwiwa, kodayake abun ciki yana da ƙarancin yawa, har yanzu ya kamata a nuna su a cikin lambar karfe. Misali 20MnVB karfe. Vanadium ne 0.07-0.12%, boron ne 0.001-0.005%.

② Babban ingancin karfe ya kamata ya ƙara 'A' a ƙarshen karfe lambar don bambanta da babban ingancin karfe.