Mechanical properties of steels with acicular ferrite structure

1. Pridneprovs’ka State Academy of Civil Engineering and Architecture Mechanical properties of steels with acicular ferrite structure Made by the student of the 832 AMS group Gerasenko K. Scientific supervisor : Ph.D. O. Uzlov Language supervisor : K. Kuznetsova Dnipropetrovsk2011

2. Microstructures of steels in different structural states • martensite structure is characterized by high strength properties with decreasing of plasticity. • Obtaining of bainite structure in steel allows to raise its strength properties without lowering plastic properties of the steel (as it happens in martensite structure). But at the time the lowering of plastic characteristics at lowered temperatures takes place. Martensite • The growth of impact toughness in the steels with acicular ferrite structure comparing with tempered martensite and bainite structure steels takes place. Bainite Acicular ferrite (x5000) 2

3. Such growth of impact toughness can be explained by the features of main crack formation. Acicular ferrite structure Bainite structure Main crack Fig. 1.1. Main crack spreading: a) along accicular ferrite grain, b) along bainite grain 3

4. Chemical compositions of investigated steels 4

5. Obtained mechanical properties of steels 5

6. Mechanical tests have been conducted according to valid State Standard and Technical Requirements. For impact toughness estimating the U-notched specimens were chosen. KCU, J/cm2 6 Testing temperature, 0C

7. Conclusion Microalloyedconstructional steel (on the base of steel 0,2C+Mn+Al+Ti+N) with acicular ferrite structure has the strength and plastic property complex similar to property complex of steels alloyed V, Nb and Mo. Therefore, in case of applying for high-strength shaped and strip rolling investigated constructional low-alloyed steel with acicular ferrite structure can substitute higher alloyed and more expensive steels such as 16Г2АФ and 09Г2ФБ. 7

8. Thank you for attention 8