Uniaxial and biaxial creep-ratcheting behavior of SUS304 stainless steel at room temperature

Abstract Uniaxial creep-ratcheting tests on SUS304 stainless steel were conducted at room temperature with or without peak stress hold. Remarkable ratchet-strain accumulation was observed in cyclic stressing owing to the viscosity of the material. In a positive-stress-ratio condition, a creep-ratcheting rate is determined as a function of a stress level and a total strain accumulation at the present time. In a negative-stress-ratio condition, the strain accumulation is affected by the cyclic strain-hardening and the memory erasure in anisotropic hardening of the material. Biaxial mechanical-ratcheting tests were also performed by subjecting thin-walled tubular specimens to combined constant internal pressure and cyclic axial straining, in which circumferential strain accumulated with an increasing number of strain cycles. The magnitude of strain accumulation in the biaxial ratcheting at a low strain rate, at a given number of cycles, was larger than that at a high strain rate.