Effect of Ni Content on Impact Toughness in Tempered Martensitic Steels




Abstract: In order to reveal the effect of Ni content on impact toughness in tempered m artensitic steels, low temperature tensile tests and Charpy impact tests were conducted L ow carbon steel with chemical composition of 0.12 C 0.2Si 1.15Mn –(0.5~0.95)Cr –(2~4 )Ni (wt%) were examin ed . Ductile to brittle transition temperature (DBTT) was improved as Ni content increased. T ensile test showed that yield strength ( YS increases with decreasing test temperature irrespective of Ni content, and the change in YS from room temp erature was smaller as the amount of Ni increased To clarify the mechanism of Ni content on YS tensile test in which strain rate was rapidly increased during tensile load was conducted. The analysis indicated that i ncrease of Ni content reduced a kink pair nucleation energy . T his results imply that the dislocation mobility is increased with Ni addition . In conclusion , the effect of Ni content on toughness improvement in low temperature attributes to suppression of YS increase in low temperature

Authors: Shigeki Kitsuya, Katsuyuki Ichimiya, and Kazukuni Hase

Keywords: steel, martensite, toughness, low temperature

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7 pages


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