For superhigh strength (UTS 600-700 MPa) alloys based on the Al-Zn-Mg-Cu system it is important to control machining technological parameters during manufacturing of parts. This paper describes the investigation results concerning residual stresses destribution and level, hardening degree and depth at the surface layers of the thin parts from B96u alloy (containing Zr addition) in T I (T6 - type) temper. It was shown the compressive residual stresses may be up to 300-400 MPa and up to 300-350 mum depth in the surface zone depending on turning conditions, tool characteristics (wear and geometry). At the top surface the tensile residual stresses of up to 100-120 MPa value may be as a result of temperature factor effect (due to friction and deformation work). It was found that the residual stresses, produced by machining, may markedly decrease elastic strength sigma(0,02) (to 60-70 MPa), yield ultimate strength sigma(0,2) (to 10-30 MPa) and creep resistance at specific temperature - time conditions. They also cause the worsening of dimension stability of parts during the serfice. The stresses relaxation has been examined.