Assessment of grinding weld treatment methods using effective notch stresses

Abstract

An experimental and numerical research program is executed to investigate the fatigue lifetime increase due to grinding-type post-weld treatment method. Plate edge gusset, longitudinal attachment and T-type joint specimens are investigated using fatigue test results, numerical models and mathematical statistical tools. The favourable impact of grinding on fatigue lifetime of the analysed joints is commonly known for researchers. However, considering the lifetime increasing effect is mainly based on experimental results. In the current research program, numerical models for as-welded and post-weld-treated specimens are developed and the lifetime increasing effect of weld treatment is investigated using effective notch stress (ENS) method. Fatigue tests are executed on as-welded and weld-treated specimens, and their results are comparatively evaluated based on numerical calculations and measured lifetimes. The results prove that the fatigue lifetime of weld treated (ground) details can be predicted with high accuracy by applying modified weld geometry in the numerical model and ENS method. Based on the current investigation, it is proved that the advantage of weld geometry treatment method comes mainly from the modification of the weld geometry at the fatigue critical point. Results also show that the same S-N curve can be applied for both as-welded and ground specimens, if the modified weld geometry is implemented in the numerical model.

A review of fatigue test data on weld toe grinding and weld profiling

“…In order to ensure a small level of additional conservatism, the results of specimens (four test series) with thickness t > 25 mm were not corrected for thickness effects; however, including a thickness correction would not affect the correlation significantly. Thus, the results by Mecséri and Kövesdi [13] and Hanzawa et al [19] could not be confirmed in this study. It can be concluded that fatigue strength improvement by means of grinding is independent of the specimen thickness.…”

“…[18]. Furthermore, the plate thickness is expected to affects the fatigue strength improvement after grinding, see Mecséri and Kövesdi [13] and Hanzawa et al [19]. In both studies, a higher fatigue strength after grinding was measured for the thicker steel plates; however, the number of performed tests is too small to draw conclusions from these comparisons.…”

“…In the Tables 3 to 9, the specimens from references Clegg et al [12]-1, Mecséri and Kövesdi [13], Booth [14], and…”

Effects of additional weld and grinding on fatigue life extension of non-load-carrying cruciform joints

“…The fatigue performance of the joints was evaluated numerically based on the prediction of fatigue crack initiation and propagation lives, where the bead geometry, angular distortion and changes in material properties by weld heat were considered [9][10][11][12][13][14] . The FE 1.…”

“…Fatigue failure of weld structures is often initiated around the welded parts due to a series of factors, such as stress concentration caused by the geometry of the welding bead, changes in material properties by heat input, residual stresses and deformations. On the other hand, grinding, TIG treatment, peening, etc., are available to improve the fatigue strength of welded joints [1][2][3][4][5][6][7][8][9][10][11][12][13][14] . Some of those methods have been standardized in JSSC 3) as improving methods to enhance the fatigue performance of joints.…”