| Popis: |
Oscillography impact properties were studied in four different temperatures. The research indicated that impact energy of sampled 4145H DC met the standard of“SYT5144-2007 Drilling collar” and “API SPEC7” in four different temperatures. With temperatures getting down, impact energy, crack propagation energy, and crack propagation energy/impact energy ratio decreased, cracking energy/impact energy ratio increased, crack propagation rate increased and dynamic fracture toughness decreased. In drilling, crack growth rate in DC was slow; the DC was not liable to fracture in normal temperature. On the contrary, crack growth rate was fast, as a result, the DC was easy to fracture in low temperature. The results provide reliable experiment resources for research on 4145H DC fracture. The research results provide reliable guidance for DC production and use in drilling and offer basic experimental evidence to the analysis of 4145H DC fracture mechanism. |
