Yuav kom nkag siab txog hlau, pib nrog hlau. Hlau yog hlau ntau tshaj plaws hauv lub ntiaj teb thiab cov khoom siv hlau uas yooj yim. Tau ntau pua xyoo, cov qhovcub hlau tau cua sov limestone thiab hlau ore uas tau raug tawm hauv av lawm. Cov cua kub siab kub thiab yaj hlau, los ntawm ntau cov tshuaj lom neeg, lub zog ua pob zeb nce mus rau saum, thiab hnyav hlau ua dej ua rau lub npua hlau. Tus npua npua no yog ib nrab ntawm cov khoom kawg.
Keeb kwm, wrought hlau yog lub tsev tsim ua los ntawm no npua hlau. Lub wrought hlau yog tsuas yog dawb huv hlau (nrog ib co slag thiab ib qho me me ntawm cov roj ntxiv). Lub wrought hlau yog tiag tiag "forged" (piv txwv li ua los yog hammered) rau hauv ib daim hlab uas tau siv los ua tsev ntaub ntawv rau ntau txhiab xyoo. Lub wrought hlau tau muaj zog thiab muaj zog thiab yog ib qho yooj yim los txhuam. Vim yog tsis muaj cov ntsiab lus ntawm cov pa roj carbon dioxide, cov hardness ntawm wrought hlau tsis txaus ua ib qho cuab yeej zoo rau cov cuab yeej los yog riam phom.
Lwm yam khoom ntawm npua hlau yog cov hlau. Cov hlau yog ob qho los yog ntau lub ntsiab, tsawg kawg yog ib qho ntawm cov hlau. Feem ntau ntawm cov hlau uas siv los tsim kho yog cov phom sij. Piv txwv li, hlau yog ib qho hlau txhuam hauv cov hlau thiab carbon yog cov ntsiab lus tseem ceeb. Feem ntau, cov hlau alloys nrog cov ntsiab lus ntawm li ntawm 2.1% yog xam ua cov hlau, thiab cov hlau cov hlau nrog cov ntsiab lus loj loj yog cov hlau nrum.
Cam khwb cia hlau yog tsim los ntawm remelting npua hlau nyob hauv lub tshuab ua kom sov, tshem cov khoom uas tsis zoo xws li phosphorus thiab leej faj, kho cov ntsiab lus, thiab ntxiv lwm yam. Lub txiaj ntsim uas muaj tshwm sim, feem ntau hu ua gray cam khwb cia hlau, muaj cov tshuaj tiv thaiv kev kub hnyiab thiab siab ceev compressive, tab sis feem ntau yog brittle thiab nyuaj rau weld. Keeb kwm, cannons thiab shells tau ua ntawm grey cam khwb cia hlau thiab ib co thaum ntxov txuas hniav.
Cov hlau yog ib qho hlau txhuam uas zoo siv hauv kev lag luam niaj hnub no. Kub-tawg, qhov ntau tshaj yog cov hlau nqaj hlau thiab steel kem hauv qhov kev tsim kho. Nws yog nyob rau hauv hlau zeb txig lub hlau mus rau hauv ib hom raug los ntawm dov hlau hlau ntawm cov yob loj: W, S, C, kaum, yeeb nkab seem, yeeb nkab Tos. Cov thermoformed hlau feem ntau muaj cov paib ntawm 36,000 psi lossis 50,000 psi.