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A high strength ductile iron shaft for a wind turbine

IP.com Disclosure Number: IPCOM000235444D
Publication Date: 2014-Feb-28
Document File: 1 page(s) / 38K

Publishing Venue

The IP.com Prior Art Database

Abstract

It is known to cast structural wind turbine parts in EN-GJS-400-18-LT; however, the use of a material with improved extreme and fatigue loading capability is desired, mainly for the main shaft.

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A high strength ductile iron shaft for a wind turbine

It is known to cast structural wind turbine parts in EN-GJS-400-18-LT; however, the use of a material with improved extreme and fatigue loading capability is desired, mainly for the main shaft.

For this reason, the present idea concerns a casted main shaft for a wind turbine produced in an iron grade with higher strength than the certified 400-18-LT grade. By addition of silicon to the melt, a stronger and yet tough iron grade is obtained, with low temperature ductility retained. A >50% increase in yield strength to approx. 390 MPa may hereby be obtained. Varying amounts of silicon may be used, such as 1, 1.5, 2, 2.5, 3, 3.5, 4, 4.5 or 5%.

The use of this stronger grade has previously been used on less heavy items, but the present idea relates to applying the stronger grade to a heavy section, such as a wind turbine main shaft, e.g. >200 mm thickness. Previously the risk of severe shrinkage defects in heavy sections have kept designers and foundries away from using this grade, as it requires a tight balance between carbon and silicon. The present grade will contain less carbon – such as down to between 3 and 4 % - which reduces the volumetric expansion of the solidified material.

With the present idea, the loading capacity of a casted main shaft is extended substantially. The idea is believed to reduce the gap between casted and forged shafts regarding strength. With the present idea, shafts can be produced in larger di...