The work is devoted to the research of strain hardening effect at short- and long-term tests, their regularities and distinctive features. The author has fulfilled systematic pilot studies of regularities of strain hardening and its influence on the creep speed at the transient stage. The studies have resulted into mathematical expressions to calculate instant creep speeds at transient stage. It has been established that strain hardening at the transient stage is reflected by the increase in the limit of fluidity, which is described by the sedate equation.