Effect of laser hardening on the fatigue strength and fracture of a B–Mn steel

Cruz, P. De La; Odén, Magnus; Ericsson, Torsten

doi:10.1016/s0142-1123(98)00010-3

Cited by 49 publications

(20 citation statements)

References 19 publications

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“…On the other hand, the decrease of the crack driving force means the increase of resistance to crack growth, and this situation can improve the fracture behavior. Besides the results presented in this work, the high residual compressive stress and high strength resulting from LTH treatment also play an important role in improving fatigue behavior [1][2][3][4][5][6][7][8], such as the decrease of the fatigue crack growth rate or the increase of resistance to crack growth [2,5,8]. Thus, the residual compressive stress and high strength from LTH treatment have a significant effect on fracture behavior in fatigue or non-fatigue cases.…”

Section: Resultsmentioning

confidence: 62%

“…6, it is assumed that there exists a crack in the middle of the hardened layer, which will propagate along the hardened track depth direction. This is a reasonable assumption since the surface and subsurface crack initiations occur independently of the applied load level, as stated in [2]. In this work, it should be emphasized the crack length, a, is assumed to be shorter than the hardened layer depth and much shorter than the total heat-treated layer depth (the total heat-treated layer depth is larger than four times of the crack length).…”

Section: The Mechanical Modelmentioning

confidence: 95%

“…Authors' report [1][2][3][4][5][6][7] stated it could improve the fatigue properties of steels, such as the increase of the fatigue limit, fatigue strength, or the decrease of the fatigue crack growth rate. Authors' report [8] stated the laser-processed specimens could exhibit a higher resistance to crack growth in the low stress intensity factor range.…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

A quantitative analysis of the effect of laser transformation hardening on crack driving force in steels

Yang

Zhang

Chen

et al. 2006

Surface and Coatings Technology

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A mechanical model of a laser transformation hardening specimen with a crack in the middle of the hardened layer is developed to quantify the effects of the residual stress and hardness gradient on crack driving force in terms of J-integral. It is assumed that the crack in the middle of the hardened layer is created after laser transformation hardening. Using a Double Cantilever Beam model, the analytic solutions, which can be used to quantify the effects of the residual stress and the hardness gradient resulting from laser transformation hardening on crack driving force, are obtained. A numerical example shows the crack driving force decrease is very sensitive to the residual compressive stress increase.

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Section: Resultsmentioning

confidence: 62%

Section: The Mechanical Modelmentioning

confidence: 95%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

A quantitative analysis of the effect of laser transformation hardening on crack driving force in steels

Yang

Zhang

Chen

et al. 2006

Surface and Coatings Technology

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show abstract

“…Though compressive stresses are obtained on the surface, tensile stresses do usually exist below the surface layer. 30,31 However for the compact tensile fatigue test, the tensile stresses only increase the mean stress instead of the stress intensity factor range DK and have very little influence on the FCGR. Furthermore, it is demonstrated that the residual stress ahead of the crack tip will significantly redistributed with the growth of the crack.…”

Section: B Residual Stressesmentioning

confidence: 99%

“…The observed enhancement of the fatigue resistance is first and foremost due to the compressive stress developed in the laser alloying zone. Even for a tensile residual stress field, beneath the hardened layer, 30 it will be redistributed with the introduction of a crack into the laser surface treated CT specimen during the fatigue crack growth. 32,35 It was reported that a tensile stress field ahead of the crack tip has only a little influence on the FCGR.…”

Section: Fatigue Behavior and Fractography Studiesmentioning

confidence: 99%

Fatigue crack propagation in laser alloyed ductile cast iron surface

Zhao

et al. 2013

Journal of Laser Applications

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Due to a limited dimension of the focused laser beam, multiple passes are required to treat large surface areas, which results in overlapping of laser tracks. This process increases the cracking susceptibility and is a major barrier for the wide application of the laser treatment. To avoid the formation of cracks in multiple overlapping laser tracks, a novel technique referred to as the laser dispersed alloying (LDA) has been developed. The technique consists of creating a dispersed pattern of laser alloying on the surface to be processed. This treatment enhances the fatigue resistance of the surface layer. In the present study, the microstructure, the residual stress, and the fatigue crack growth rate (FCGR) for the ductile cast iron surface formed with the LDA technique were investigated. It was found that the fatigue resistance of the ductile cast iron is markedly increased after the LDA process, due to the compressive stresses and the fine dendritic structure formed in the laser alloying zone, the excellent bond strength between the laser alloying zone and the substrate, and the martensite shell surrounding graphite nodule in the heat affected zone near the boundary of the laser alloying zone. V C 2013 Laser Institute of America.

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50 Hz X‐Ray Diffraction Stress Analysis and Numerical Process Simulation at Laser Surface Line Hardening of Web Structures

et al. 2021

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The improvement of surface layers of structural steel components is of great importance in mechanical engineering, as failure for highly stressed technical components, as e.g., the formation of fatigue cracks or oxidization, initiates primarily at the very surfaces. Here, surface hardening heat treatments [1] provide a suitable tool to increase wear and fatigue strength. Among the multitude of surface hardening processes, [1] laser surface hardening became increasingly popular in the past few decades, even more so with the development of High-Power Diode Lasers (HPDL). [2][3][4] The process is characterized by the precise and local heating of a steel workpiece using a focused laser beam, thereby austenitizing the process zone, followed by rapid self-quenching through heat conduction into the surrounding cold material and hence martensitic hardening. This surface hardening is accompanied by the formation of favorable residual stress states, i.e., predominantly compressive stresses, inside the process zone. The advantages of laser surface hardening over other steel hardening processes are i) the minimal distortion due to the fast and precise heat input, ii) the omitted requirement for a secondary quenching medium, and therefore, a high and flexible automation capability, and iii) the reduced environmental impact due to a lower power consumption. A brief description and explanation of the laser hardening process was given by Ion. [5] A lot of research was already done on laser surface hardening, mostly focusing on the numerical process prediction of the hardening result, e.g., hardening depth, width, and degree. [6][7][8][9][10] Only minor interest was given to the formation of residual stresses induced by laser surface hardening. De la Cruz et al., [11] for example, showed the positive effect of laser surface hardening on fatigue resistance in comparison with quenched and tempered material states due to the induced compressive residual stresses. In literature, there are multiple different numerical models which allow the prognosis of transient process stresses and resulting residual stresses, e.g., studies by Liverani et al., Müller et al., and Bailey et al.,[9,12,13] at low cost and effort. However, in our judgment, the transient process stress and residual stress prediction by

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Effect of laser hardening on the fatigue strength and fracture of a B–Mn steel

Cited by 49 publications

References 19 publications

A quantitative analysis of the effect of laser transformation hardening on crack driving force in steels

A quantitative analysis of the effect of laser transformation hardening on crack driving force in steels

Fatigue crack propagation in laser alloyed ductile cast iron surface

50 Hz X‐Ray Diffraction Stress Analysis and Numerical Process Simulation at Laser Surface Line Hardening of Web Structures

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