Abstract: method of constant ΔK value is applied experimentally to investigate chemical short crack characteristics in GC-4 high-strength steel in3.5% NaCl solution. experimental results show that there is a critical crack size a on da/dN-a curve of the crack propagation at constant ΔK value. When crack size a < a, chemical short crack effect appears. Loading frequency,stress ratio and ΔK value almost have no effect on a value. The ratio of characteristic crack propagation rate of chemical short crack to that of long crack is a weak function of foading fre-quency,stress ratio and ΔK value. Based on the analysis, the relation between the short crack propagation rate and crack size has been put forward.

Key words: stress intensity factors, chemical properties short cracks, critical point-crack geome-try, crack propagation