ASTM A29 covers hot-rolled carbon and alloy round steel bars, specifying chemical composition, mechanical properties, and dimensional tolerances. It includes grades like 1018 (low-carbon) and 4140 (alloy), with requirements for tensile strength (e.g., 4140: 620 MPa min), elongation (15% min for 4140), and hardness (217 HB max for annealed 4140). The standard mandates ultrasonic testing for bars >2 inches diameter for at detektere interne defekter. Det definerer også tilladte variationer i diameter (± 0,015 inches for 1-2 tommer bar) for at sikre udskiftelighed i fremstillingen.