Determination of ductile-to-brittle transition temperature of NIOMOL 490K steel welded joints

Abstract

This paper is devoted to the ductile–brittle transition behavior of high strength low alloyed structural steel NIOMOL 490K. This steel grade is designed for welded pressure vessels exposed to dynamic loads, operating at temperatures below zero, and that is why it must have acceptable toughness. Due to its importance for the safety assessment of pressure vessels, a characterization of this steel with Charpy V-notch test in range of temperature between-60 ⁰C and +60 ⁰C was undertaken. Ductile-to-brittle transition temperature curves were generated in the present study by using instrumented Charpy pendulum impact test on V-notch specimens. Notches were located in the parent material, heat-affected zone and weld metal. The nil-ductility temperature and tensile properties in temperature range from -60 ⁰C to +60 ⁰C are presented in this paper. We used different test temperatures to better understand ductile-to brittle transition response than just use either Charpy energy or other related ductility criteria.