Cov tshuaj muaj pes tsawg leeg ntawm steel yog qhov tseem ceeb. Qhov siab dua cov alloy muaj pes tsawg leeg ntawm cov hlau, qhov nyuaj dua nws yog tshuab. Thaum cov ntsiab lus carbon nce, cov hlau txiav kev ua haujlwm qis.
Cov qauv ntawm cov hlau kuj tseem ceeb heev rau cov hlau txiav kev ua haujlwm. Cov qauv sib txawv muaj xws li: forged, cam khwb cia, extruded, dov thiab machined. Forgings thiab castings muaj qhov chaw uas nyuaj heev rau tshuab.
Hardness yog qhov tseem ceeb cuam tshuam rau kev ua haujlwm ntawm hlau. Txoj cai dav dav yog tias qhov nyuaj ntawm cov hlau, qhov nyuaj rau lub tshuab. High-speed steel (HSS) tuaj yeem siv los ua cov khoom siv nrog lub hardness txog li 330-400 HB; high-speed steel ntxiv rau titanium nitride (TiN) txheej tuaj yeem siv rau cov khoom siv nrog lub hardness txog li 45 HRC; thiab rau cov ntaub ntawv uas muaj hardness ntawm 65-70 HRC, cemented carbide, ceramics, cermets thiab cubic boron nitride (CBN) yuav tsum tau siv.
Non-metallic inclusions feem ntau muaj kev cuam tshuam tsis zoo rau lub neej ntawm cov cuab yeej. Piv txwv li, Al2O3 (alumina), uas yog ib tug ntshiab ceramic, yog heev abrasive.
Qhov kawg yog qhov kev ntxhov siab seem, uas tuaj yeem ua rau muaj teeb meem kev ua haujlwm ntawm hlau. Kev ua haujlwm ntawm kev ntxhov siab feem ntau pom zoo tom qab kev ua haujlwm ntxhib.