scholarly journals Evaluation of Hardness and Residual Stress Changes of AISI 4140 Steel Due to Thermal Load during Surface Grinding

2021 ◽  
Vol 5 (3) ◽  
pp. 73
Author(s):  
Ewald Kohls ◽  
Carsten Heinzel ◽  
Marco Eich
Keyword(s):  
Residual Stresses ◽  
Numerical Approach ◽  
Absolute Temperature ◽  
Surface Grinding ◽  
Maximum Temperature ◽  
Thermal Loads ◽  
Aisi 4140 Steel ◽  
Stress Changes ◽  
Aisi 4140 ◽  
Hardness Change

During surface grinding, internal material loads are generated, which take effect on the surface and subsurface zone of AISI 4140 steel. High thermal loads can result in specific material modifications, e.g., hardness reduction and tensile residual stresses, due to inappropriate combinations of system and process parameters which influence the functional performance of the ground component in a negative way. In order to avoid this damaging impact due to the thermal effect, an in-depth understanding of the thermal loads and the resulting modifications is required. This relationship is described in the concept of Process Signatures applied in this paper. Experimentally determined temperature-time histories at various depths below the surface were used to estimate the thermal loads at the surface and subsurface using a numerical approach based on the finite element method (FEM). The results show that the hardness change during surface grinding correlates with the maximum temperature rate at given maximum temperatures. In addition, correlations between the hardness change and the Hollomon–Jaffe parameter are identified, taking into account both the absolute temperature and its evolution over time. Furthermore, it was shown that the surface residual stresses correlate with the maximum local temperature gradients at the surface if no detectable tempering of the microstructure takes place.

Investigating the correlation between magnetic Barkhausen noise emission and the fatigue life of shot-peened AISI 4140 steel

2019 ◽  
Vol 61 (12) ◽  
pp. 701-705
Author(s):  
S Çalışkan ◽  
C Hakan Gür
Keyword(s):  
Residual Stress ◽  
Fatigue Life ◽  
Residual Stresses ◽  
Shot Peening ◽  
Critical Parameters ◽  
Barkhausen Noise ◽  
Magnetic Barkhausen Noise ◽  
Surface Residual Stress ◽  
Aisi 4140 Steel ◽  
Aisi 4140

The performance of engineering components under conditions of fatigue can be improved by shot peening. The location and magnitude of the highest residual compressive stress, the depth of the compression zone and the stability of the residual stress state during cyclic loading are critical parameters for maximum utilisation of the advantageous influence of shot peening on fatigue performance. For accurate assessment of fatigue lifetime, residual stresses should be considered because they are algebraically summed with applied stresses. Therefore, the development of a non-destructive testing (NDT) method that has the ability to rapidly monitor surface residual stresses has industrial importance when verifying the achievement of the design goals of shot peening. The utilisation potential of the magnetic Barkhausen noise (MBN) technique in shot peening of ferromagnetic steels includes automated sorting of the components and measurement of surface residual stress. This study aims to establish the correlation between MBN emission and the fatigue life of shot-peened AISI 4140 steel.

Weld quality and productivity of AISI 4140 steel welded by unpulsed and pulsed GMAW

2018 ◽  
Vol 60 (2) ◽  
pp. 149-155 ◽  
Author(s):  
Turhan Kursun ◽  
Tanju Teker
Keyword(s):  
Weld Quality ◽  
Aisi 4140 Steel ◽  
Aisi 4140

scholarly journals Thermal Effects on Surface and Subsurface Modifications in Laser-Combined Deep Rolling

2021 ◽  
Vol 5 (2) ◽  
pp. 55
Author(s):  
Robert Zmich ◽  
Daniel Meyer
Keyword(s):  
Surface Layer ◽  
Residual Stresses ◽  
Thermal Loads ◽  
Deep Rolling ◽  
Mechanical Loads ◽  
Thermomechanical Process ◽  
Compressive Stresses ◽  
New Process ◽  
Negative Effect ◽  
Compressive Residual Stresses

Knowledge of the relationships between thermomechanical process loads and the resulting modifications in the surface layer enables targeted adjustments of the required surface integrity independent of the manufacturing process. In various processes with thermomechanical impact, thermal and mechanical loads act simultaneously and affect each other. Thus, the effects on the modifications are interdependent. To gain a better understanding of the interactions of the two loads, it is necessary to vary thermal and mechanical loads independently. A new process of laser-combined deep rolling can fulfil exactly this requirement. The presented findings demonstrate that thermal loads can support the generation of residual compressive stresses to a certain extent. If the thermal loads are increased further, this has a negative effect on the surface layer and the residual stresses are shifted in the direction of tension. The results show the optimum range of thermal loads to further increase the compressive residual stresses in the surface layer and allow to gain a better understanding of the interactions between thermal and mechanical loads.

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