Published on 21 January 2013
A project at Abington has helped to provide a sound basis for deciding on the suitability of steels with yield strengths between 450 and 550 N/mm2 for given applications.
Developments in steel making practices mean that higher strength steels can be obtained without significant increases in alloy levels and in greater thicknesses.
The potential advantages of these developments, mainly in saving weight and in reducing fabrication costs, have not been exploited as much as expected. One reason for this was believed to be a general lack of information on weldability and weldment properties.
To provide data, steels in the range 15 to 50mm thickness were examined: three quenched and tempered, one processed by thermomechanically controlled rolling and accelerated controlled cooling, and one controlled rolled and aged. All steels were initially characterised in terms of strength, Charpy toughness, hardness, chemical composition and microstructure. Work was then divided into welded panel testing to determine weld metal and HAZ properties, and weldability tests for HAZ and weld metal hydrogen cracking.
In general, these higher strength materials were found to behave as would be expected according to their chemical compositions, based on current experience with approximately 350 N/mm2 yield (grade 50) carbon manganese steels.
From the data generated it has been concluded that such materials are suitable candidates, with normal weld procedure testing, for use in major constructions where high quality grade 50 steels would previously have been used and where economies in weight and weld volume would be advantageous.
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