Influence of the slot inclination angle in FeP04 steel on fatigue crack growth under tension

The paper contains the results of an experimental investigation of the crack path and description of fatigue crack growth rate in plane specimens made of FeP04 steel under tension. For the tests under tension the plane specimens with central, symmetric stress concentrator in the form of the slots with side notches were used. The results of the experimental tests have been described by a formula based on the J-integral. The fatigue crack growth for mixed mode I + II, for the slot inclination angles φ = 45° and 60°, was observed only in the initial stage of cracking up to 1 mm length.