Strain and temperature-controlled solid-state bonding in high-strength steel: model validation and application to void healing in laser cladding

Laser-cladding repair of high-strength steels leaves porosity and oxide-covered interfaces that degrade mechanical performance. This study clarifies how interfacial strain and temperature control solid-state pressure bonding in EA4T axle steel, validates a physics-based bonding model, and applies the insights to heal voids in laser-clad material. Half-bar couples and laser-clad/wrought pairs were hot-compressed to engineering strains of 0.1–0.5 at 9001000and 1100 °C. EBSD/SEM-EDS characterised oxide fragmentation and grain continuity; tensile tests measured bond strength; finite-element (FE) simulations supplied local strain and normal-stress fields for model validation. A critical local strain of ~ 0.25 initiates bonding, while 50% height reduction produces wrought-strength joints independent of temperature. Temperature chiefly influences bonding at moderate strains by altering interface normal stress; at high strain its effect is negligible. The validated FE model accurately reproduces oxide-film rupture, extrusion pressure and the transition from oxide-oxide to metal-metal contact, confirming its predictive capability. Applying the optimum laser-cladding + hot-forming (LHD) condition (≥ 0.5 strain, 900–1100 °C) removes all observable voids and restores wrought-equivalent properties: ultimate tensile strength ~ 680 MPa and elongation ~ 25%. The work provides quantitative processing windows and a validated model for defect-free remanufacturing of high-strength steel components, advancing both mechanistic understanding and industrial practice. Clarifies solid-state pressure-bonding mechanisms in high-strength EA4T steel. Quantifies how interfacial strain vs. temperature govern bond formation quality. Validates a physics-based bonding model through FE simulation and experiments. Demonstrates void-free joints by 50% strain hot forming of laser-clad EA4T.