Icyuma cyimyanda nicyiza kubikoresho bya valve, kuko bifite ibyiza byinshi.Mu rwego rwo gusimbuza ibyuma, ibyuma byangiza byatejwe imbere mu 1949. Ibirimo bya karubone biri mu byuma bikozwe munsi ya 0.3%, mu gihe ibyuma bikozwe mu byuma n’ibyuma byibura byibuze 3%.Ibirimo bike bya karubone yibyuma bituma karubone ibaho nka grafite yubusa ntabwo ikora flake.Ubwoko busanzwe bwa karubone mubyuma ni grafite ya flake.Mu byuma byangiza, grafite iri muburyo bwa nodules aho kuba flake nko mubyuma.Ugereranije nicyuma gikozwe nicyuma, ibyuma byangiza bifite imiterere myiza yumubiri.Nibizunguruka byiziritse bibuza kurema ibice, bityo bigatanga ihindagurika ryongerewe ritanga amavuta izina ryayo.Nyamara, flake mu byuma bitera itera kubura ibyuma.Guhindagurika kwiza kurashobora kuboneka na matrise ya ferrite.

Ugereranije nicyuma, ibyuma byangiza bifite ibyiza byuzuye mumbaraga.Imbaraga zingana zicyuma cyimyanda ni 60k, mugihe icyuma gikozwe ni 31k gusa.Imbaraga zibyuma byumuyaga ni 40k, ariko icyuma gikozwe ntigaragaza imbaraga zumusaruro kandi kizacika amaherezo.

Imbaraga zibyuma byangirika bigereranywa nibyuma.Icyuma cyangiza gifite imbaraga nyinshi zo gutanga umusaruro.Imbaraga zitanga umusaruro muke wicyuma cyimyanda ni 40k, mugihe imbaraga zibyuma byibyuma ari 36k gusa.Mubikorwa byinshi bya komini, nkamazi, amazi yumunyu, amavuta, kurwanya ruswa no kurwanya okiside yicyuma cyangiza kiruta icyuma.Icyuma cyangiza kandi kizwi nka spheroidal grafite icyuma.Bitewe na microstructure ya spheroidal, fer ductile iruta ibyuma byo kugabanya ibinyeganyega, bityo rero bikaba byiza kugabanya imihangayiko.Impamvu y'ingenzi yo guhitamo icyuma kidahinduka nkibikoresho bya valve nuko ifite igiciro gito ugereranije nicyuma.Igiciro gito cyicyuma cyimyanda ituma ibi bikoresho bikundwa cyane.Uretse ibyo, guhitamo icyuma gishobora kugabanya igiciro cyo gukora.