scholarly journals Understanding The Effect Of Residual Stresses On Surface Integrity And How To Measure Them By A Non Destructive Method

2020 ◽  
Author(s):  
Daniel Magda
Keyword(s):  
Residual Stresses ◽  
Surface Integrity ◽  
Non Destructive

Non-Destructive Inspection of Surface Integrity in Milled Turbine Blades of Inconel 738LC

2013 ◽  
Vol 486 ◽  
pp. 9-15 ◽  
Author(s):  
Kamil Kolařík ◽  
Zdenek Pala ◽  
Libor Beranek ◽  
Jiří Čapek ◽  
Zdenek Vyskocil ◽  
...  
Keyword(s):  
Residual Stresses ◽  
Surface Integrity ◽  
Turbine Blades ◽  
Mutual Effect ◽  
Work Piece ◽  
Machined Surface ◽  
Grain Sizes ◽  
Cutter Orientation ◽  
Inconel 738Lc ◽  
Non Destructive

Nickel super-alloys are widely used in aerospace as material for turbine blades. Unfortunately, their machining is difficult since mechanical hardening and, consequently, extreme tool wear occur. Casting can no longer meet the requirements for precision, hence, the castings are being ground or milled. In this contribution, a quality check of the milled surface by several surface integrity parameters is proposed with respect to the surface structural inhomogeneities caused by mutual effect of plastic deformations and thermal fields during the cutting process. Castings from Inconel 738LC were milled with cutting conditions chosen by Design-Of-Experiments method and the resulting surfaces were assessed by non-destructive X-ray diffraction methods in several areas corresponding to various cutter orientation and work-piece angle. Surface integrity was described by macroscopic residual stresses, microstrains, grain sizes and phase composition. Mostly, favourable compressive surface residual stresses were observed in the cutting direction, grain sizes were distinctively smaller when the tool axis was perpendicular to the machined surface.

scholarly journals Evaluation of Non-Equibiaxial Residual Stresses in Metallic Materials via Instrumented Spherical Indentation

Metals ◽  
2020 ◽  
Vol 10 (4) ◽  
pp. 440 ◽  
Author(s):  
Guangjian Peng ◽  
Fenglei Xu ◽  
Jianfeng Chen ◽  
Huadong Wang ◽  
Jiangjiang Hu ◽  
...  
Keyword(s):  
Residual Stresses ◽  
Mechanical Performance ◽  
Asymmetry Factor ◽  
Spherical Indentation ◽  
Engineering Structures ◽  
Surface Residual Stresses ◽  
Aa 7075 ◽  
Relative Change ◽  
Non Destructive ◽  
Indentation Imprint

Residual stresses, existed in engineering structures, could significantly influence the mechanical properties of structures. Accurate and non-destructive evaluation of the non-equibiaxial residual stresses in these structures is of great value for predicting their mechanical performance. In this work, investigating the mechanical behaviors of instrumented spherical indentation on stressed samples revealed that non-equibiaxial residual stresses could shift the load-depth curve upwards or downwards and cause the residual indentation imprint to be an elliptical one. Through theoretical, experimental, and finite element (FE) analyses, two characteristic indentation parameters, i.e., the relative change in loading curvature and the asymmetry factor of the residual indentation imprint, were found to have optimal sensitivity to residual stresses at a depth of 0.01R (R is the radius of spherical indenter). With the aid of dimensional analysis and FE simulations, non-equibiaxial residual stresses were quantitatively correlated with these two characteristic indentation parameters. The spherical indentation method was then proposed to evaluate non-equibiaxial residual stress based on these two correlations. Applications were illustrated on metallic samples (AA 7075-T6 and AA 2014-T6) with various introduced stresses. Both the numerical and experimental verifications demonstrated that the proposed method could evaluate non-equibiaxial surface residual stresses with reasonable accuracy.

Analysis and Prediction of Surface Integrity in Machining: A Review

2014 ◽  
Vol 610 ◽  
pp. 1002-1020 ◽  
Author(s):  
Yuan Gao ◽  
Xin Huang ◽  
Ming Jie Lin ◽  
Zheng Guo Wang ◽  
Rong Lei Sun
Keyword(s):  
Surface Roughness ◽  
Grain Size ◽  
Residual Stresses ◽  
Surface Integrity ◽  
Material Properties ◽  
Cutting Parameters ◽  
Mechanical Parameters ◽  
Factors Affecting ◽  
Grain Size And Shape

Surface integrity is widely used for evaluating the quality of machined components. It has a set of various parameters which can be grouped as: (a) topography parameters such as surface roughness, textures and waviness (b) mechanical parameters such as residual stresses and hardness, and (c) metallurgical state such as microstructure, phase transformation, grain size and shape, inclusions etc. Surface roughness and residual stresses are among the most significant parameters of surface integrity, so that it is worth investigating them particularly. Many factors affect the surface integrity of machined components, including cutting parameters, tool parameters, material properties and vibrations. We can make prediction and optimization for surface integrity by taking advantage of these factors. This paper reviews previous studies and gives a comprehensive summary of surface integrity in the following order: introduction of surface integrity, main parameters of surface integrity, factors affecting surface integrity, prediction and optimization for surface integrity.

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