The carbon content in round steel significantly affects its properties. As the carbon content increases, the strength and hardness of the round steel increase. Low - carbon round steel has good ductility and weldability, making it suitable for applications that require forming and joining. Medium - carbon round steel offers a balance between strength, ductility, and toughness, suitable for parts that Angen gwrthsefyll llwythi cymedrol . Uchel - Mae gan ddur crwn carbon galedwch uchel a hydwythedd isel, gan ei wneud yn ddelfrydol ar gyfer cymwysiadau lle mae angen ymwrthedd i wisgo uchel, ond mae'n anoddach prosesu .