scholarly journals Fatigue Life Improvement of the High Strength Steel Welded Joints by Ultrasonic Impact Peening

Metals ◽  
2019 ◽  
Vol 9 (6) ◽  
pp. 619 ◽  
Author(s):  
Ján Lago ◽  
Libor Trško ◽  
Michal Jambor ◽  
František Nový ◽  
Otakar Bokůvka ◽  
...  
Keyword(s):  
Residual Stress ◽  
Fatigue Life ◽  
Welded Joints ◽  
Compressive Residual Stress ◽  
High Strength ◽  
Fatigue Properties ◽  
Low Alloy Steel ◽  
Residual Stress Field ◽  
Near Surface ◽  
Life Improvement

Ultrasonic impact peening was applied on welded joints manufactured from Strenx 700 MC high strength low alloy steel with the aim to improve the fatigue properties. Three different surface treatment parameters were tested, which resulted in transformation of the near-surface tensile residual stresses in the weld metal and heat affected zone to compressive residual stress field, while maximal values from −400 MPa up to −800 MPa were reached. The highest fatigue life improvement was reached by the double peening with the 85 N contact force, where the fatigue limit for N = 108 cycles increased from 370 MPa to 410 MPa.

scholarly journals Effects of shot peening and artificial surface defects on fatigue properties of 50CrV4 steel

2021 ◽  
Vol 112 (9-10) ◽  
pp. 2961-2970
Author(s):  
Nursen Saklakoglu ◽  
Amir Bolouri ◽  
Simge Gencalp Irizalp ◽  
Fatih Baris ◽  
Ali Elmas
Keyword(s):  
Residual Stress ◽  
Fatigue Life ◽  
Shot Peening ◽  
Compressive Residual Stress ◽  
Surface Defects ◽  
Fatigue Properties ◽  
Root Radius ◽  
Defect Depth ◽  
Near Surface ◽  
Artificial Surface

AbstractShot peening processes are commonly used for improving the fatigue properties of steels. Shot peening introduces a compressive residual stress field in the near surface of steel, which can reduce or stop the growth of fatigue cracks and improve fatigue properties. This study experimentally investigated the effect of shot peening on the fatigue properties of 50CrV4 steel alloys with different artificial surface defects. Drilling tools were used to introduce different artificial defects with root radii of 0.585 mm and 0.895 mm on the surface of unpeened samples. The shot peening was applied to the drilled and undrilled samples. Scanning electron microscopy (SEM) observations, micro-hardness and X-ray diffraction residual stress measurements were conducted to analyse the characteristics of the shot-peened and unpeened samples. The results show that the shot peening leads to the transformation of the retained austenite to martensite in the near-surface microstructure. The hardness rates of the surface and near surface both increase by 8% after the shot peening. The peened samples exhibit compressive residual stresses with a high degree of isotropy in the near surface. The fatigue properties of samples were experimentally evaluated by conducting 3-point bending tests. The results indicate that the shot peening improves the fatigue life of drilled and undrilled samples. For the defects with the root radius of 0.895 mm, the shot peening leads to a 500% improvement in the fatigue life compared to unpeened samples regardless of defect depth. For the defects with the root radius of 0.585 mm, the improvement in fatigue life is 40% for the defect depth of 0.2 mm compared to unpeened samples. The improvement increases to 60% and 200% by increasing the defect depths to 0.4 mm and 0.6 mm. The fatigue properties are linked to the changes in the features of defects mainly caused by the deformation hardening and compressive residual stress after shot peening.

FATIGUE PROPERTIES OF HYBRID SURFACE MODIFIED SCM435H STEEL

2006 ◽  
Vol 20 (25n27) ◽  
pp. 3646-3651
Author(s):  
SHOICHI KIKUCHI ◽  
KENGO FUKAZAWA ◽  
JUN KOMOTORI ◽  
MASAO SHIMIZU
Keyword(s):  
Residual Stress ◽  
Surface Modification ◽  
Compressive Residual Stress ◽  
Induction Hardening ◽  
Hardened Layer ◽  
Fatigue Tests ◽  
Fatigue Properties ◽  
Residual Stress Field ◽  
Modification Process ◽  
Surface Modified

In order to clarify the effects of nitriding and hybrid surface modification process combining nitriding and induction hardening on fatigue properties of SCM435H steel, high cycle fatigue tests were carried out with a rotational bending machine at room temperature. Observations of fracture surfaces and measurement of hardness and residual stress distributions were carried out to investigate the fracture mechanism. It was revealed that hybrid surface modification process generated a compressive residual stress field and hardened even at center of the specimen. Fatigue strength of hybrid surface modified specimens was much higher than that of substrate and nitrided specimens. This was because a transition of fracture mode from internal to surface fracture; fatigue fracture of nitrided specimens occurred at inside of the hardened layer, in the case of hybrid surface modified specimens, however, fatigue crack initiated at the surface of the specimen with higher hardness and higher compressive residual stress.

scholarly journals Small–Scale Experimental Investigation of Fatigue Performance Improvement of Ship Hatch Corner with Shot Peening Treatments by Considering Residual Stress Relaxation

2021 ◽  
Vol 9 (4) ◽  
pp. 419
Author(s):  
Jin Gan ◽  
Zi’ang Gao ◽  
Yiwen Wang ◽  
Zhou Wang ◽  
Weiguo Wu
Keyword(s):  
Residual Stress ◽  
Surface Roughness ◽  
Fatigue Life ◽  
Stress Relaxation ◽  
Stress Field ◽  
Shot Peening ◽  
Compressive Residual Stress ◽  
Fatigue Performance ◽  
Residual Stress Field ◽  
Residual Stress Relaxation

Ship hatch corner is a common structure in a ship and its fatigue problem has always been one of the focuses in ship engineering due to the long–term high–stress concentration state during the ship’s life. For investigating the fatigue life improvement of the ship hatch corner under different shot peening (SP) treatments, a series of fatigue tests, residual stress and surface topography measurements were conducted for SP specimens. Furthermore, the distributions of the surface residual stress are measured with varying numbers of cyclic loads, investigating the residual stress relaxation during cyclic loading. The results show that no matter which SP process parameters are used, the fatigue lives of the shot–peened ship hatch corner specimens are longer than those at unpeened specimens. The relaxation rate of the residual stress mainly depends on the maximum compressive residual stress (σRSmax) and the depth of the maximum compressive residual stress (δmax). The larger the values of σRSmax and δmax, the slower the relaxation rates of the residual stress field. The results imply that the effect of residual stress field and surface roughness should be considered comprehensively to improve the fatigue life of the ship hatch corner with SP treatment. The increase in peening intensity (PI) within a certain range can increase the depth of the compressive residual stress field (CRSF), so the fatigue performance of the ship hatch corner is improved. Once the PI exceeds a certain value, the surface damage caused by the increase in surface roughness will not be offset by the CRSF and the fatigue life cannot be improved optimally. This research provides an approach of fatigue performance enhancement for ship hatch corners in engineering application.

scholarly journals Microstructure and residual stress analysis of Strenx 700 MC welded joint

2020 ◽  
Vol 26 (2) ◽  
pp. 41-44
Author(s):  
Libor Trško ◽  
Ján Lago ◽  
Michal Jambor ◽  
František Nový ◽  
Otakar Bokůvka ◽  
...  
Keyword(s):  
Residual Stress ◽  
Heat Affected Zone ◽  
Microstructural Analysis ◽  
Fatigue Crack Initiation ◽  
Welding Process ◽  
High Strength ◽  
Carbon Steels ◽  
Fatigue Properties ◽  
Residual Stress Field ◽  
Welded Structure

AbstractHigh strength low alloy (HSLA) steels are a new generation of plain carbon steels with significantly improved mechanical properties while maintaining good weldability with common commercial techniques. Residual stress and microstructural analysis of welded HSLA Strenx 700 MC was carried out in this research. Results have shown that the welding process causes significant grain coarsening in the heat affected zone. The microstructural changes are also accompanied with creation of tensile residual stress field in the weld metal and heat affected zone, reaching up-to depth of 4 mm. Tensile residual stresses are well known for acceleration of fatigue crack initiation and together with coarse grains can lead to significant decrease of the fatigue properties of the welded structure.

Fatigue improvement in high-strength steel welded joints with compressive residual stress

2013 ◽  
Vol 58 (1) ◽  
pp. 55-64 ◽  
Author(s):  
Chiaki Shiga ◽  
Eiichi Murakawa ◽  
Yuki Matsuo ◽  
Uusuke Ohsuga ◽  
Kazuo Hiraoka ◽  
...  
Keyword(s):  
Residual Stress ◽  
Welded Joints ◽  
High Strength Steel ◽  
Compressive Residual Stress ◽  
High Strength ◽  
Fatigue Improvement

Numerical Study on Strengthening Effect of Laser Shot Peening for Wrought Magnesium Alloy

2012 ◽  
Vol 217-219 ◽  
pp. 2234-2237 ◽  
Author(s):  
Su Qin Jiang ◽  
Hong Guang Xu
Keyword(s):  
Residual Stress ◽  
Fatigue Life ◽  
Shot Peening ◽  
Compressive Residual Stress ◽  
Numerical Study ◽  
Back Analysis ◽  
Laser Shot ◽  
Fatigue Properties ◽  
Strengthening Effect ◽  
Fea Model

Based on finite element method, the FEA model used for analyzing fatigue properties of sample treated by laser shot peening (LSP) was established. In order to research the influence of material intensity on LSP effect, two kinds of wrought magnesium alloys AZ31B and ZK60 with different intensity were chosen as object, the compressive residual stress and fatigue life after LSP were analyzed. After spring back analysis the elastic strain is released in material inner, the value of compressive residual stress was reduced; after LSP with 3 times, the fatigue life gains of AZ31B and ZK60 were 105% and 163%, respectively. The results show that strengthening effect of high intensity material treated by LSP is better than that of low intensity material.

3D Computational Simulation of Multi-Impact Shot Peening

2012 ◽  
Vol 1485 ◽  
pp. 35-40
Author(s):  
Juan Solórzano-López ◽  
Francisco Alfredo García-Pastor
Keyword(s):  
Residual Stress ◽  
Fatigue Life ◽  
Stress Field ◽  
Surface Treatment ◽  
Shot Peening ◽  
Compressive Residual Stress ◽  
Fatigue Testing ◽  
Computational Simulation ◽  
Target Material ◽  
Residual Stress Field

ABSTRACTShot peening is a widely applied surface treatment in a number of manufacturing processes in several industries including automotive, mechanical and aeronautical. This surface treatment is used with the aim of increasing surface toughness and extending fatigue life. The increased performance during fatigue testing of the peened components is mainly the result of the sub-surface compressive residual stress field resulting from the plastic deformation of the surface layers of the target material, caused by the high-velocity impact of the shot. This compressive residual stress field hinders the propagation and coalescence of cracks during the second stage of fatigue testing, effectively increasing the fatigue life well beyond the expected life of a non-peened component.This paper describes a 3D computational model of spherical projectiles impacting simultaneously upon a flat surface. The multi-impact model was developed in ABAQUS/Explicit using finite element method (FEM) and taking into account controlling parameters such as the velocity of the projectiles, their incidence angle and different impact locations in the target surface. Additionally, a parametric study of the physical properties of the target material was carried out in order to assess the effect of temperature on the residual stress field.The simulation has been able to successfully represent a multi-impact processing scenario, showing the indentation caused by each individual shot, as well as the residual stress field for each impact and the interaction between each one of them. It has been found that there is a beneficial effect on the residual stress field magnitude when shot peening is carried out at a relatively high temperature. The results are discussed in terms of the current shot-peening practice in the local industry and the leading edge developments of new peening technologies. Finally, an improved and affordable processing route to increase the fatigue life of automotive components is suggested.

A Study on the Development of Mach Peening for Prolonging Fatigue Life of Machine Structural Alloy Steel

2008 ◽  
Vol 580-582 ◽  
pp. 621-624
Author(s):  
Bok Kyu Lim
Keyword(s):  
Residual Stress ◽  
Fatigue Life ◽  
Fatigue Strength ◽  
Alloy Steel ◽  
Compressive Residual Stress ◽  
Fatigue Tests ◽  
Fatigue Properties ◽  
Light Weight ◽  
Structural Alloy ◽  
Bending Fatigue

The light weight components, crucial in automobiles and machinery, is require hight strength. Mach peening process is one of many of techniques utilized for improving fatigue properties. From the results of rotary bending fatigue tests, the fatigue strength increases up to 129% in mach peening specimen compared with un-peening. A layer of highly compressed residual stress is obtained by mach peening. The compressive residual stress, induced by mach peening, seems to be an important factor for increasing the fatigue strength.

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