Dynamic properties of iron and a variety of steels over a wide range of strain rates

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The tensile stress-strain curves of iron and a variety of steels, covering a wide range of strength level, which compose a material group of ferrous metals, over a wide strain rate range on the order of 10^<-3>〜10^3 s^<-1>, were obtained systematically by using the Sensing Block Type High Speed Material Testing System (SBTS, Saginomiya). The tested materials are an electrolytic pure iron (LW1), an ulutra-low carbon interstitial-free miled steel (SPCE ; 270 MPa grade IF steel), a cold rolled pure iron (PF), a cold rolled mild steel (SPCE), a cold-reduced carbon steel (SPCC), cold rolled high strength steels (SPFC440 and SPFC590), DP590, a 1200 MPa grade martensitic type high strength steel (MT), and a 1500 MPa grade martensitic type high strength steel (M1500). Through intensive analysis of these results obtained systematically, the strain rate sensitivity of the flow stress for the large strain region, including the viscous term at high strain rates, the true fracture strength and the trure fracture strain of iron and steels, over the wide range of strain rates, were cleared for the material group of the ferrous metals. New unified sets of values of parameters of the modified constitutive model (Tanimura-Mimura Yield Model) were obtained. One set can be used for homogenous deformation and the other can be used for a wide strain range extended to the true fracture strain. Both of the sets can be used to simulate the stress-strain curves of any material belonging to the material group of ferrous metals, over a wide strain rate range, as long as the quasistatic tensile stress-strain curves of the material concerned is known in advance.