Laser Polishing Die Steel Assisted by Steady Magnetic Field

Area of Science:

• Materials Science
• Manufacturing Engineering
• Surface Engineering

Background:

• SKD61 die steel requires improved surface roughness for optimal performance.
• Molten pool secondary overflow is a challenge in laser-based surface treatments.
• Controlling melt pool dynamics is crucial for achieving desired surface morphology.

Purpose of the Study:

• To investigate the effect of a steady magnetic field on laser polishing of SKD61 die steel.
• To reduce surface roughness and mitigate secondary overflow of the molten pool.
• To analyze the influence of magnetic fields on melt pool flow behavior.

Main Methods:

• A two-step laser polishing approach: pulsed laser for impurity removal, followed by CW laser with a steady magnetic field.
• Development of a multi-physical-field numerical transient model (heat transfer, laminar flow, electromagnetic field).
• Experimental measurement of surface roughness and molten pool depth for validation.

Main Results:

• Surface roughness of SKD61 die steel reduced from 6.1 μm to 0.607 μm (90.05% decrease).
• Steady magnetic field inhibited molten pool secondary overflow by reducing melt pool velocity.
• Numerical simulation showed good agreement with experimental molten pool depth (15.0% error).

Conclusions:

• Steady magnetic field-assisted laser polishing is effective for improving SKD61 die steel surface quality.
• The magnetic field's role in controlling melt pool flow is critical for surface finish enhancement.
• The validated numerical model accurately predicts melt pool behavior, aiding process optimization.