Influence of austenite structure and its decay products on the quasi-brittle fracture of high strength plate for building construction

Influence of the grain size austenite on the formation of bainite, the fracture surface and toughness values of steel plate. Methodology. As a basic material for study was chosen is traditionally used in the construction of low-carbon low alloy steel 09G2S to compare close in chemical composition, but different strength and production technology, high-strength microalloyed steel 10G2FB. We studied: micro- and substructure bainite fractographic especially destruction of various geometrical parameters of packets of bainite and their influence on the toughness indices. Results. Conducted complex investigations possible to establish the relationship between the structure of austenite, the formation of bainite lath, fracture toughness, and surface of 09G2S 10G2FB steels. Originality. It is found that the reason for the decrease in toughness of the hot rolled plate and 09G2S 10G2FB steels is the formation of fractures in portions quasi-brittle cracking which are associated with an increase in bainite structure steel component, formed from relatively large (65 ?m) of austenite grains. Practical significance. The relationship of micro- and substructure - the cracking of the surface - toughness enable to adjust operating modes controlled rolling in the manufacture of steel 10G2FB to stabilize the mechanical properties and reduce the rejection toughness.