On the mechanism of quench cracking in Rene 95 nickel-based superalloy

The mechanism of quench cracking in the nickel-based superalloy Rene 95 has been investigated. Rapid cooling of notched tensile bars loaded with fixed grips was used to mimic a quench. Failures occurred by brittle intergranular fracture in air, but by rupture and at higher stress in vacuum. The brittle intergranular fracture in air was recognized as dynamic embrittlement. Nickel-plating of sufficient thickness was found to eliminate cracking when Rene 95 was water-quenched from above the γ′ solvus temperature.