Characterisation of Residual Stress due to Fillet Rolling on Bolts Made of a Nickel Base Superalloy

Wei Li,Saurabh Kabra,Henry Kirkwood,Erin T Mcdevitt,Brian Abbey,Serigne Ndoye,Daniel Terret,Shu Yan Zhang,Anton Tremsin

doi:10.4028/www.scientific.net/amr.996.670

Abstract

This paper investigates residual stress due to fillet rolling on bolts made of ATI 718Plus® superalloy. Incremental hole drilling, neutron diffraction and neutron transmission have been used to assess residual stress near the bolt head fillet. A compressive residual stress field was identified in the first 0.5 mm from the surface. Post fillet rolling solution anneal can relieve the residual stress at the fillet.

Highlights

A bolt underhead fillet is the junction of the cylindrical surface of the bolt shank and the perpendicular surface of the bolt head, which is an area of high stress concentration.Bolts operating in harsh service conditions can fail due to fatigue crack initiated at the fillet [1]
Given the significant difference in spatial resolution between the Hole drilling (HD) and Neutron Diffraction (ND) methods, the stress profiles for the fillet rolled (FR) condition measured by the two methods shows a reasonable consistency, both showing an increasing tension with depth increased to greater than 0.5mm
The significant difference between the as-forged and the fillet rolled (FR) results indicates fillet rolling has drastically changed the residual stress field originally induced by bolt-head forging

Summary

Introduction

A bolt underhead fillet is the junction of the cylindrical surface of the bolt shank and the perpendicular surface of the bolt head, which is an area of high stress concentration. Bolts operating in harsh service conditions can fail due to fatigue crack initiated at the fillet [1]. As a result fillet rolling is often used in the bolt manufacturing process to induce compressive residual stress to improve its fatigue Bolt head. As is limited by the geometry of the bolt, residual stress. The capability of creating 3D strain tomography from the neutron transmission data for genuine engineering components is demonstrated for the first time in literature

Methods

Results

Conclusion