Microstructural design for damage tolerance in high strength steels

•Evolutions of damage in 1G and 3G steels are quantified using X-ray tomography.•Grain refinement is found to increase damage tolerance in the steels.•Transformation induced plasticity significantly increases damage tolerance.•Influences of Grain refinement and TRIP are reported on RT model coefficients.•Grain refinement and TRIP are recommended for microstructural design of 3G steels.