boron effect; low carbon steel wire rod notch toughnessNotch Toughness in Hot-Rolled Low Carbon Steel Wire Rod

摘要

Charpy V-notch toughness has been investigatedin four hot-rolled, low carbon steels with different grain sizesand carbon contents between 0.019 and 0.057 percent. The rawmaterial was wire rod designed for drawing and possiblesubsequent cold heading operations and manufactured fromcontinuous cast billets. In this study, the influence ofmicrostructure, mechanical properties, and alloying elements onthe ductile-brittle transition behavior has been assessed. Aparticular emphasis has been given to the influence of boronwith contents up to 0.0097 percent.As a result, transition temperatures between -29 and +50 deg Cexplicated by the material properties have been obtained. Theexamination also shows that the transition temperature raiseswith circa 0.5 deg C for each added ppm boron most likely as aconsequence of an enlargement of the ferrite grain size and thereduction of yield and tensile strength. The highest upper shelfenergy and lowest transition temperature can be observed in asteel without boron additions and with maximum contents ofcarbon, silicon, and manganese.