Abstract: Creep crack growth behavior has been investigated in CT-specimen of as-cast HK40 steel at temperatures of 1103, 1123, 1144 and 1163K. Apparent activation energies for creep and creep crack growth have been measured in the temperature range of 1103 to 1163K and over limited ranges of stress and temperature similar values are calculated. This means that a creep mechanism may control the crack growth rate. The creep crack growth behavior of cast and two creep damaged specimens is different. The crack growth rate of cast specimen increases more quickly than that of creep damaged specimen with the increase of the stress intensity factor. It is the main reason of the higher crack growth rate of DB1 that the area fraction of cavities for DB1 is larger than that for YB2. The fine secondary carbide makes the crack growth rate quicken.

Key words: HK40钢, 蠕变裂纹扩展, 蠕变损伤