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The mechanical properties at room and low temperature of P110 steel characterised by means of small punch test

Romelczyk-Baishya B., Lumelskyj D., Stępniewska M., Giżyński M., Pakieła Z.

Archives of Metallurgy and Materials

2019

Vol. 64, iss. 1

159--165

In this paper small punch test (SPT) which is one of miniaturized samples technique, was employed to characterize the mechanical properties of carbon steel P110. The tests were carried out in the range of -175°C to RT. Results obtained for SPT were compared to those calculated for tensile and Charpy impact test. Based on tensile and SPT parameters numerical model was prepared. 8 mm in diameter and 0.8 mm in height (t) discs with and without notch were employed in this research. The specimens had different depth notch (a) in the range of 0.1 to 0.4 mm. It was estimated that α factor for comparison of Tsp and DBTT for carbon steel P110 is 0.55 and the linear relation is DBTT = 0.55TSPT. The numerical model fit with force – deflection curve of SPT. If the factor of notch depth and samples thickness is higher than 0.3 the fracture mode is transformed from ductile to brittle at -150°C.

The effect of microstructure anisotropy on low temperature fracture of ultrafine-grained iron

Romelczyk-Baishya B., Łęczycki K., Płocińska M., Kulczyk M., Molak R., Pakieła Z.

Archives of Civil and Mechanical Engineering

2018

Vol. 18, no. 4

1166--1182

This papers deals with the character on low (−180 °C) temperature fracture of iron. Microcrystalline and ultrafine-grained (UFG) iron rods were investigated. To obtain UFG material 20 mm in diameter iron rod was hydrostatically extruded (HE) in two steps: from 20 to 12 mm and from 12 to 8 mm. Because of microstructure anisotropy caused by HE mini-disc and mini-beam samples were cut off from perpendicular and longitudinal cross-section of the rods. Microcrystalline rod fractured in brittle manner at low temperature for both cross-sections, but in UFG iron fracture character depended on grain's shape. For samples were crack propagates parallel to the grain's elongation axis intercrystalline fracture occurred. For mini-beams were crack propagates crosswise to the grain elongation axis transcrystalline fracture occurred and force deflection curve was similar to those obtained for room temperature.