Dalabyada maalgashiga birta ee cawlan ayaa ah alaabada shubka ah ee lagu shubay geedi socodka shubista maalgashiga dhuka ee luntay ee goobta birta ah. Birta cawlan (ama birta cawlan) waa nooc ka mid ah daawaynta kaarboon-kaarbon (ama Ferrum-Carbon Alloy) kaas oo leh qaab-dhismeed yar oo garaafeed ah. Waxaa lagu magacaabaa midabka cawl ee jabka uu sameeyo. 
