Microstructure investigation on inner crack thermal healing in Q235 steel with La addition

Author

Zhao, Zhongli

Author_Institution

Beijing Univ. of Chem. Technol., Beijing, China

fYear

2010

fDate

26-28 June 2010

Firstpage

3860

Lastpage

3863

Abstract

Thermal healing experiment to inner crack made by compressing a drilled hole on samples of Q235 steel with various La addition was carried out. The effects of various heating temperature on the appearance and morphology evolution of inner crack healing in Q235 steel were investigated. Optical microscope and SEM observation indicate that artificial inner crack samples of Q235 steel with La addition can occur healing phenomenon at 650°C, while inner crack samples have apparent healing at 800°C and the microstructure in healing area is mainly ferrite. La in the solute solution decreases the critical healing temperature, makes the microstructure in host appear obvious variety during crack healing, not only decreases the quantity of pearlite and its shape becomes like-pearlite or granular but also increases the quantity of ferrite and the concentration of carbon in ferrite. The healing process was controlled by the diffusion and migration of Fe atoms from steel host to crack zone.

Keywords

cracks; iron; lanthanum; optical microscopes; scanning electron microscopy; steel; Fe; La; Q235 steel; SEM; crack healing; crack zone; drilled hole compression; ferrite; inner crack thermal healing; microstructure investigation; morphology evolution; optical microscope; steel host; temperature 650 C; temperature 800 C; Ferrites; Heating; Microstructure; Morphology; Optical microscopy; Process control; Scanning electron microscopy; Shape; Steel; Temperature; La; Q235 steel; inner crack; thermal healing;

fLanguage

English

Publisher

ieee

Conference_Titel

Mechanic Automation and Control Engineering (MACE), 2010 International Conference on

Conference_Location

Wuhan

Print_ISBN

978-1-4244-7737-1

Type

conf

DOI

10.1109/MACE.2010.5536550

Filename

5536550