A new technical approach for real-time tensile strength testing of high-temperature granite based on micro-tensile testing technology

• A novel micro-tensile testing method enables reliable real-time high-temperature tensile strength measurements on granite, validated by a power-law size effect model with errors below 6%. • Granite tensile strength exhibits non-monotonic temperature dependence: it increases up to 300 °C, then decreases with sharp drops at 400–500 °C and 600–700 °C. • Thermal damage in granite under high temperatures is driven by mineral dehydration, phase transformations, and differential thermal expansion. • The proposed approach addresses the challenge of limited standard sample availability for deep hot dry rock mechanical testing.