Thermomechanical modelling of laser surface glazing for H13 tool steel

Abstract

A two-dimensional thermomechanical finite element (FE) model of laser surface glazing (LSG) has been developed for H13 tool steel. The direct coupling technique of ANSYS 17.2 (APDL) has been utilised to solve the transient thermomechanical process. A H13 tool steel cylindrical cross-section has been modelled for laser power 200 W and 300 W at constant 0.2 mm beam width and 0.15 ms residence time. The model can predict temperature distribution, stress-strain increments in elastic and plastic region with time and space. The crack formation tendency also can be assumed by analysing the von Mises stress in the heat-concentrated zone. Isotropic and kinematic hardening models have been applied separately to predict the after-yield phenomena. At 200 W laser power, the peak surface temperature achieved is 1520 K which is below the melting point (1727 K) of H13 tool steel. For laser power 300 W, the peak surface temperature is 2523 K. Tensile residual stresses on surface have been found after cooling, which are in agreement with literature. Isotropic model shows higher residual stress that increases with laser power. Conversely, kinematic model gives lower residual stress which decreases with laser power. Therefore, both plasticity models could work in LSG for H13 tool steel.

Comparing and analysing the characterisation of laser cladding of CrNiW and CrNiFeAlZr powders on H13 tool steel

“…The sufficiency measurements, such as adjusted R 2 , are closer to 1, as required, demonstrating the model’s fitness. For clad height of CrNiFeAlZr powder (shown in Table 6), laser power (A); scanning speed (B); feed rate (C) and interactions BC, A 2 , B 2 and C 2 are essential model terms. The ‘Pred R 2 ’ of 0.9362 is in reasonable agreement with the ‘Adj R 2 ’ of 0.9856.…”

“…1 Tool steels such as H11 and H13 are widely used in hot working conditions such as forging, die casting and extrusion. 2 H13 tool steel has dimensional stability, great hot working properties and high surface toughness properties even at a temperature range of 200–800°C. Due to repeated thermal cycles, the life of the dies reduces gradually and fails over a period of time.…”

Thermo-Mechanical Finite Element Modeling of the Laser Treatment of Titanium Cold-Sprayed Coatings

“…This phenomenon is clearer in the test Case B_200 where a more effective heat dissipation took place due to the presence of the aluminum substrate. Nonetheless, observing the equivalent Von Mises stresses (Figure 9), that describe the overall stress state inside the material and can be used as effective indicator to understand the crack formation [30], the surface in the observed tests experienced values between 10 and 20 MPa, far below the elastic limit of the materials. Therefore, no crack formation is expected, as confirmed by the experimental data [14,16].…”

Scaling analysis for rapid estimation of lack of fusion porosity in laser powder bed fusion

“…The values of the porosity fraction are almost Table 2. Ranges of process conditions and measured porosity fraction values for LPBF of Ti6Al4V [4,20,24], SS316L [22,23,25,26], AlSi10Mg [5,27], H13 [28,29], and IN718 [6,21,30] powder and material properties [31][32][33] used for the analytical model [19]. Conductivity, k [20,24], IN718 [6,21], SS316L [25,26], AlSi10Mg [27], and H13 [28,29].…”