Some creep mechanisms acting at low stresseshave not their own primary stage. Nevertheless, the primarycreep has been observed in almost all low stress creepexperiments. Hence, special primary creep mechanisms must beresponsible for primary creep under such loading conditions.The primary creep parameters like primary strain, the durationof primary creep stage, initial creep rate and initial to secondarycreep rate ratio are analyzed for several metallic materials frompure metals to heat-resistant steel. The initial structural state ofthe material is naturally important for the primary creepbehaviour, but even in materials with similar structural state theprimary creep parameters exhibit large differences. It can beconcluded, that no mechanism proposed till now for primarycreep at low stresses is capable to explain all observed featuresof primary creep under given conditions.
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