Thermomechanical modelling of laser surface glazing for H13 tool steel

I R Kabir,S Naher,D Yin,N Tamanna

doi:10.1007/s00339-018-1671-9

I R Kabir, S Naher + Show 2 more

Open Access

https://doi.org/10.1007/s00339-018-1671-9

Copy DOI

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.

Highlights

H13 tool steel is predominantly utilised in tooling industries especially forging tools, die casting moulds (Cu, Al alloys casting), extrusion dies, moulds for glass industry, etc
Because of simultaneous thermal and mechanical effects caused by the abrasion of high-velocity molten metals during casting, the conventional H13 tool steel mould experiences softening, erosion and thermal fatigue, etc
The model output has been analysed for 200 W and 300 W laser power with constant 0.2 mm beam width and 0.15 ms residence time considering the stationary laser beam as a line heat source with constant heat flux

Summary

Introduction

H13 tool steel is predominantly utilised in tooling industries especially forging tools, die casting moulds (Cu, Al alloys casting), extrusion dies, moulds for glass industry, etc. Through modelling and simulation, scientists have been trying to predict the residual stresses in laser surface modification techniques of different materials (metals and alloys) and correlating with process parameters [13,14,15]. The use of higher energy density (106–109 Wm− 2) and shorter interaction or residence time ( 10− 4 s) differ LSG from other laser melting processes, which results in very high cooling rates (104–108 Ks− 1) [22] This higher rate of cooling causes amorphisation making surface very hard and resistant to softening at elevated temperature, while simultaneously developing residual stress in modified zone [4, 23,24,25,26]. The results will be compared for laser power and between two plasticity models

Models and methodology

Numerical formulation

Thermal distribution and temperature change rate

Stress and strain

Findings

Conclusion