scholarly journals Characterization method of the layer thickness of surface residual stress based on instrumented indentation testing

AIP Advances ◽  
2019 ◽  
Vol 9 (9) ◽  
pp. 095024
Author(s):  
MingHao Zhao ◽  
Xinxin Xu ◽  
Sheng Liang ◽  
JianWei Zhang
Keyword(s):  
Residual Stress ◽  
Layer Thickness ◽  
Indentation Testing ◽  
Instrumented Indentation ◽  
Surface Residual Stress

Surface residual stress in soda-lime glass evaluated using instrumented spherical indentation testing

2015 ◽  
Vol 50 (23) ◽  
pp. 7752-7759 ◽  
Author(s):  
Seung-min Ahn ◽  
Sun-Young Park ◽  
Young-Cheon Kim ◽  
Kang-Sun Lee ◽  
Ju-Young Kim
Keyword(s):  
Residual Stress ◽  
Soda Lime ◽  
Spherical Indentation ◽  
Soda Lime Glass ◽  
Indentation Testing ◽  
Surface Residual Stress

Directionality of residual stress evaluated by instrumented indentation testing using wedge indenter

2017 ◽  
Vol 23 (3) ◽  
pp. 465-472 ◽  
Author(s):  
Hee-Jun Ahn ◽  
Jong-hyoung Kim ◽  
Huiwen Xu ◽  
Junsang Lee ◽  
Ju-Young Kim ◽  
...  
Keyword(s):  
Residual Stress ◽  
Indentation Testing ◽  
Instrumented Indentation

scholarly journals Application of Macro-Instrumented Indentation Test for Superficial Residual Stress and Mechanical Properties Measurement for HY Steel Welded T-Joints

Materials ◽  
2021 ◽  
Vol 14 (8) ◽  
pp. 2061
Author(s):  
Junsang Lee ◽  
Kyungyul Lee ◽  
Seungha Lee ◽  
Oh Min Kwon ◽  
Won-Ki Kang ◽  
...  
Keyword(s):  
Residual Stress ◽  
Yield Strength ◽  
Arc Welding ◽  
Volume Fraction ◽  
Indentation Test ◽  
Uniaxial Tensile ◽  
Uniaxial Tensile Test ◽  
Indentation Testing ◽  
Instrumented Indentation ◽  
Flux Cored Arc Welding

HY-80 and HY-100 steels, widely used in constructing large ocean vessels and submarine hulls, contain mixed microstructures of tempered bainite and martensite and provide high tensile strength and toughness. Weld integrity in HY steels has been studied to verify and optimize welding conditions. In this study, the T-joint weld coupons, HY80 and HY100, were fabricated from HY-80 and HY-100 steel plates with a thickness of 30 mm as base metals by submerged-arc welding. Flux-cored arc welding was performed on an additional welding coupon consisting of HY-100 to evaluate the effect of repair welds (HY100RP). Microstructures in the heat-affected zones (HAZ) were thoroughly analyzed by optical observation. Instrumented indentation testing, taking advantage of local characterization, was applied to assess the yield strength and the residual stress of the HAZ and base regions. The maximum hardness over 400 HV was found in the HAZ due to the high volume fraction of untempered martensite microstructure. The yield strength of the weld coupons was evaluated by indentation testing, and the results showed good agreement with the uniaxial tensile test (within 10% range). The three coupons showed similar indentation residual stress profiles on the top and bottom surfaces. The stress distribution of the HY100 coupon was comparable to the results from X-ray diffraction. HY100RP demonstrated increased tensile residual stress compared to the as-welded coupon due to the effect of the repair weld (323 and 103 MPa on the top and bottom surfaces). This study verifies the wide applicability of indentation testing in evaluating yield strength and residual stress.

Estimation of Stress-Free State From Hardness Ratio for Evaluation of Residual Stress Using Instrumented Indentation Testing (IIT)

2015 ◽  
Author(s):  
Jong-Hyoung Kim ◽  
Hee-Jun Ahn ◽  
Seung-Won Jeon ◽  
June Sang Lee ◽  
Min-Jae Choi ◽  
...  
Keyword(s):  
Residual Stress ◽  
Welding Residual Stress ◽  
Free State ◽  
Indentation Testing ◽  
Instrumented Indentation ◽  
K Value ◽  
Hardness Ratio ◽  
Stress Free State ◽  
Free Material ◽  
Depth Curve

As welding residual stress is a primary factor in serious failure or fracture of plants, many testing methods such as X-ray diffraction, hole-drilling, and saw-cutting are used to evaluate this welding residual stress. Instrumented Indentation Testing (IIT) is an attractive testing method for evaluating welding residual stress because it is nondestructive and can be used in-field. The material properties can be obtained by Instrumented Indentation Testing in field using attachments like magnetic device or chain device. In general, the principle of evaluation of residual stress with IIT is based on comparing the load-depth curves obtained from stress-free state and stressed state which are same material. However, as the mechanical properties of welds are altered during welding process, it is difficult to obtain the load-depth curve for stress-free state of welds. In this research, in order to estimate the load-depth curve for the stress-free state, we consider the relation between k value of Kick’s law which is related to the slope of the load-depth curve and the hardness value which is independent of residual stress state. The relation between maximum load and maximum indentation depth which is k value of Kick’s law is similar to the concept of hardness and as a result, the ratio of k value between two materials is almost equal to the ratio of their hardness values. To validate this research, we compare the load-depth curve of stress-free material with the load-depth curve which is estimated from hardness ratio.

Determination of Residual Stress Directionality by Instrumented Indentation Testing Using Anisotropic Indenter

2018 ◽  
Author(s):  
Sungki Choi ◽  
Jong Hyoung Kim ◽  
Jun Sang Lee ◽  
Kyungyul Lee ◽  
Min-Jae Choi ◽  
...  
Keyword(s):  
Residual Stress ◽  
Indentation Test ◽  
Surface Preparation ◽  
Field Testing ◽  
Indentation Load ◽  
Indentation Testing ◽  
Instrumented Indentation ◽  
Element Analysis ◽  
Knoop Indenter ◽  
Depth Curves

Residual stress is a major factor in failure and fracture in structures or electronic components. Various testing methods are used to measure residual stress: there are saw-cutting, holedrilling, X-ray diffraction and layer-removing methods. In particular, instrumented indentation testing (IIT) has many advantages: it is a simple and non-destructive procedure that can be used for in-field testing. In previous research, we proposed an algorithm for evaluating the magnitude and directionality of residual stress using an asymmetric Knoop indenter with long and short axes in the ratio 7.11:1. Indenting in different directions with a Knoop indenter creates different indentation load-depth curves depending on the residual stress state. In addition, the directionality of the residual stress can be expressed as a function of the load difference ratio calculated from these load-depth curves. However, When the Knoop indentation test is performed at small indentation depths, experimental issues such as surface preparation or indentation normality can become significant as the load difference decreases. In order to solve these issues, we introduce a wedge indenter, that makes it possible to select the edge length independent of indentation depth. We can thus decrease indent size when working in a small testing area. The load difference between the stress-free and stressed state is related to the sensitivity of residual stresses, and a wedge indenter can maximize the sensitivity to residual stress. In this study, we suggest a way to use the wedge indenter and verify the model using cruciform bending specimens and finite element analysis.

The Effect of Specimen Thickness on Low Temperature Gaseous Carburization of 316L Austenitic Stainless Steel

2018 ◽  
Author(s):  
Yong Jiang ◽  
Peng-peng Zhang ◽  
Jianming Gong
Keyword(s):  
Residual Stress ◽  
Stainless Steel ◽  
Austenitic Stainless Steel ◽  
Low Temperature ◽  
Residual Stresses ◽  
Layer Thickness ◽  
Specimen Thickness ◽  
Surface Residual Stress ◽  
Carburized Layer ◽  
Compressive Residual Stresses

In this present paper, the effect of specimen thickness on carburized layer thickness and surface residual stress of low temperature gaseous carburized AISI316L austenitic stainless steel was investigated by using specimen with thicknesses from ∼0.1 to ∼3 mm. After 15 and 30 hrs Low Temperature Gaseous Carburization (LTGC) treatment, the carburized layer thickness, surface residual stress and surface morphology were studied by optical microscope (OM), X-ray residual stress analyzer and scanning electron microscope (SEM). The results show that the specimen original thickness has no effect on the thickness of carburized layer. Surface compressive residual stresses are constant as about −1.6 and −2.1 GPa when the specimen thicknesses are not less than 0.485 mm for 15 hrs and 0.926 mm for 30 hrs LTGC treatment respectively. With the reduction of specimen thicknesses from 0.485 to 0.081 mm for 15 hrs LTGC treatment and 0.926 to 0.082 mm for 30 hrs LTGC treatment, the compressive residual stresses declined and finally reached about +0.4 and +1.0 GPa, respectively. Surface inter-granular cracking occurred on 0.082 mm specimen after 30 hrs LTGC treatment.

TEM investigations of surface residual stress relaxation in A12O3 and Al2O3-SiC nanocomposite

1994 ◽  
Vol 52 ◽  
pp. 628-629
Author(s):  
J. Fang ◽  
H. M. Chan ◽  
M. P. Harmer
Keyword(s):  
Residual Stress ◽  
Single Phase ◽  
Stress Relief ◽  
Stress Recovery ◽  
Surface Residual Stress ◽  
Microscopic Mechanism ◽  
Sic Particles ◽  
Annealing Procedure ◽  
The Difference ◽  
Nano Size

It was Niihara et al. who first discovered that the fracture strength of Al2O3 can be increased by incorporating as little as 5 vol.% of nano-size SiC particles (>1000 MPa), and that the strength would be improved further by a simple annealing procedure (>1500 MPa). This discovery has stimulated intense interest on Al2O3/SiC nanocomposites. Recent indentation studies by Fang et al. have shown that residual stress relief was more difficult in the nanocomposite than in pure Al2O3. In the present work, TEM was employed to investigate the microscopic mechanism(s) for the difference in the residual stress recovery in these two materials.Bulk samples of hot-pressed single phase Al2O3, and Al2O3 containing 5 vol.% 0.15 μm SiC particles were simultaneously polished with 15 μm diamond compound. Each sample was cut into two pieces, one of which was subsequently annealed at 1300° for 2 hours in flowing argon. Disks of 3 mm in diameter were cut from bulk samples.

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