Low Plasticity Burnishing (LPB) Treatment to Mitigate FOD and Corrosion Fatigue Damage in 17-4 PH Stainless Steel

Abstract

The benefits of applying low plasticity burnishing (LPB) to 17-4PH Stainless Steel (H1100) on both the fatigue and corrosion fatigue performance were compared with the shot peened (SP) and low stress ground (LSG) conditions. LPB treatment dramatically improved both the high cycle fatigue (HCF) performance and fatigue strength. The baseline LSG and SP treatments showed similar fatigue strengths of about 150 ksi (~1035 MPa), while LPB treatment improved the fatigue strength by about 30%. Introduction of an EDM notch of a o = 0.010 in. (0.25 mm) and c o = 0.030 in. (0.75 mm) simulating a semi-elliptical surface foreign object damage (FOD), decreased the fatigue strength of both SP and LSG by nearly 80%, while LPB helped retain much of the fatigue strength at the levels comparable to baseline material without FOD. Corrosion fatigue strength (in the presence of active corrosion medium of 3.5% NaCl solution) of the LSG material showed a drop of nearly 33% from the baseline material without corrosion; LPB material showed corrosion fatigue strength nearly the same as the baseline material without corrosion. While the introduction of a simulated FOD on the LSG dramatically decreased the fatigue strength to less than 15 ksi (~100 MPa), LPB retained nearly 90% of the fatigue strength of the baseline material without corrosion. Mechanistically, the effect of corrosion and FOD resulted in early crack initiation and growth, thus resulting in a dramatic decrease in fatigue performance. Despite the existence of s imilar corrosion conditions, the deep compressive surface residual stresses from LPB treatment helped to mitigate the individual and synergistic effects of corrosion fatigue and FOD.

Technology vision

“…A number of studies have demonstrated significant enhancement in the mechanical properties through residual stress engineering. For example, up to 10 times increase in fatigue life has been achieved through various peening technologies 1,2. Recent technological advancement in modelling and simulation has set the stage for incorporating residual stresses at the design stage, rather than accounting for them through large and ad hoc factors of safety.…”

“…During many of the newly developed processes, e.g. coating or peening methods, residual stresses are often measured and their impact on the fatigue life is quantified 1,2. However, this information is rarely utilised in the transportation sector at the design stage to create an optimal product.…”

“…Although significant amount of work has been carried out on understanding the performance improvement, e.g. fatigue life, through these treatments,1,2 very limited work has been carried out on the inverse problem of estimating the possibility of weight reduction through residual stress engineering. The significant focus on Tier IV and carbon footprint reduction effort in the automotive and off highway sectors provides an opportunity to leverage residual stress engineering for weight reduction.…”

The Influence of the Burnishing Process on the Change in Surface Hardness, Selected Surface Roughness Parameters and the Material Ratio of the Welded Joint of Aluminum Tubes

“…Low plasticity burnishing, developed and patented by Lambda Technologies, also referred to as “roller burnishing” e.g., by Ecoroll Company and Klocke and Liermann [ 21 ] or “ball burnishing” by López et al [ 22 ], is intended to reduce both the surface roughness and high and deep compressive residual stresses. The main difference concerning deep rolling is that high residual stresses are obtained with reduced work hardening [ 23 , 24 , 25 ] mainly due to the large size of the spherical indenter. This type of burnishing is usually performed on ordinary machine tools, with a hydrostatic bearing system for the ball roller, which requires a pressure unit.…”

Enhancing surface properties and corrosion resistance of API 5L X52 steel through orthogonal ball burnishing

“…In all cases, the generated surface results from a controlled and carefully applied pressure using a ball or roller, without any change in volume, structure, or chemical composition of the material to impart specific physical, mechanical, and tribological properties [17]. The process provides good corrosion resistance and improved fatigue life [18]. A literature review has shown that numerous experimental studies have been conducted to identify the effects of burnishing on surface quality and surface microhardness.…”