Effect of Hydrogen on Fracture of Bend Specimens of Spheroidized AlSl 1095 Steel U-Notched

The effect of hydrogen on fracture was studied in U-notch bend specimens of 1095 s t e e l with t h r e e different notch acuities. The hydrogen was introduced by cathodic charging through the notch surfaces. Both precharging and dynamic charging effects on void initiation and growth, c r a c k initiation and fracture were investigated. In precharged specimens voids were initiated at lower strains and the void population increased more rapidly than in the uncharged c a s e . The role of hydrogen is t o promote plastic instability a l o n g c h a r acteristic slip l ines and therefore accelerate void formation. In the dynamically cha rged specimens, c r a c k s initiated at lower strains than for the other ca se s and propagated rapidly without accompanying void formation. The results are compared to those for the uncharged case and t o previous theoretical and experimental results.