Hlau yog ib qho ntawm cov khoom siv feem ntau siv rau kev tsim kho tshuab.Nws muaj ntau yam khoom, thiab nws cov khoom tseem ceeb yog hlau thiab carbon.Hlau yog refined hlau.Peb feem ntau hu nws hlau alloy steel.Txhawm rau kom ntseeg tau tias nws lub zog thiab plasticity, cov ntsiab lus carbon feem ntau tsis tshaj 1.7%.Ntxiv rau cov hlau thiab hlau, cov ntsiab lus tseem ceeb ntawm cov hlau yog silicon, carbon manganese, sulfur, phosphorus thiab lwm yam.