Turnbull, A; Pitts, J J; Lord, J D (2006) Residual stress relaxation in shot-peened high strength low alloy steel. NPL Report. DEPC-MPE 024

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Abstract

The relaxation of residual stress in a shot-peened high strength low alloy steel in response to applied loads has been investigated for both single-shot and cyclic loading. The near surface residual stress was measured predominantly by X-ray diffraction (first 10-20 µm) but supplemented for some conditions by measurements using high resolution, fine increment hole-drilling to yield depth profiling. The compressive residual stress showed a peak at about 50 µm below the surface. Under single-shot compressive loading, relaxation became significant when the combined surface and applied compressive stresses exceeded the proportional limit of the unpeened surface. The steel showed good resistance to residual stress relaxation under cyclic loading conditions, with only a 13% decrease despite cyclic load amplitudes at 50% of the 0.2% proof stress in compression. Significant relaxation did occur at applied stress amplitudes of about 80% of the 0.2% proof stress in compression. Whilst large singleshot or cyclic stresses would represent rare occurrences, they could lead to a marked loss in beneficial compressive stress and should be accounted for in structural integrity assessment.

Item Type:	Report/Guide (NPL Report)
NPL Report No.:	DEPC-MPE 024
Subjects:	Advanced Materials Advanced Materials > Metals and Alloys Advanced Materials > Mechanical Measurement
Last Modified:	02 Feb 2018 13:16
URI:	http://eprintspublications.npl.co.uk/id/eprint/3408

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