Residual Stress Enhancement by Laser Shock Treatment in Chromium-Alloyed Steam Turbine Blades

Abstract

In-service turbine blade failures remain a source of concern and research interest for engineers and industry professionals with attendant safety and economic implications. Very high-pressure shock impacts from laser shots represent an evolving technique currently gaining traction for surface improvement and failure mitigation in engineering components. However, the physical characteristics and effects of parameter variations on a wide range of materials are still not fully understood and adequately researched, especially from a computational point of view. Using the commercial finite element code ABAQUS©, this paper explores the application of laser shock peening (LSP) in the enhancement of residual stresses in Chromium-based steel alloyed turbine blade material. Results of the numerically developed and experimentally validated LSP model show that peak compressive residual stresses (CRS) of up to 700 MPa can be induced on the surface and sub-surface layers, while the informed varying of input parameters can be used to achieve an increase in the magnitude of CRS imparted in the peened material. Analysis of the hierarchy of influence of the five input parameters under investigation on residual stress enhancement reveals the laser shock intensity as the most influential, followed in descending order of influence by the exposure time, shot size, degree of overlaps, and the angle of shot impact.

Boundary Layer Modelling of Flow Acceleration and Energy Transfer Effects in Smart Pavement Design

“…The outcomes enable decision-makers to capture the varying component conditions in one infrastructure system (i.e., stormwater drainage system) and depict the aggravated adverse impacts on its interdependent infrastructure system (i.e., road transport system) after a hazard has occurred. The continuous advancement and development of high-performance computing technology according to [26] and [27] has opened up vistas of new possibilities and opportunities in applied scientific research, paving the way for deeper investigations than as witnessed in the past. This has also found application in flood modelling and management as demonstrated by [28] in their assessment of dual-drainage modelling to determine the effects of green stormwater infrastructure on roadway flooding and traffic performance using microscopic flow simulations to examine the specific hazard of roadway flooding and the effects of flooding on traffic performance.…”

Effect of Laser Shock Peening on the Fatigue Life of 1Cr12Ni3Mo2VN Steel for Steam Turbine Blades

“…Considering the advantages of LSP over other strengthening methods, researchers have applied LSP to steam turbine blades. For example, simulation and experimental investigations by Fameso F [31] revealed that the energy intensity of LSP was the main influencing factor for increasing the residual stress in blade materials. In addition, Sundar R [32] found that the depth of the residual stress layer generated in the blade root after LSP treatment was more than 900 µm.…”

“…In addition, Sundar R [32] found that the depth of the residual stress layer generated in the blade root after LSP treatment was more than 900 µm. However, though the blade material introduced a large residual stress after LSP, researchers [31][32][33][34] did not perform fatigue experiments on the strengthened blade material to verify its fatigue life, indicating the need for further research on the influence of LSP.…”

Modelling and optimization of residual stress induction on laser-worked X12Cr turbine blades

“…According to [2], as opposed to experimental set-ups which are relatively costly and mostly invariable, flexible, time-saving computational models have made the prediction of mechanical effects and responses of metallic materials to laser shot impacts more robust and in-depth, with a wider spectrum of laser peening phenomena now opened for investigation.…”