1. High performance steel shows slightly higher fracture toughness at low temperature and has a significantly lower transition temperature than the ASTM A36 steel. HPS from two different heats produced at different times showed significantly different toughness properties.2. Crack initiation properties of HPS are similar to conventional structural steels in terms of strain and energy, but, because of their superior strength, they are very different in terms of stress. The fatigue crack initiation properties of the higher toughness HPS 485W steel, do not seem to be better than those of the lower toughness HPS (LT) steel. The smooth HPS specimens tested showed a significant higher fatigue limit than conventional structural steels.3. A comparison of crack propagation properties indicates that HPS behaves similarly to conventional grades of structural steel.4. Experimental results on plates with a circular hole detail made from HPS steel show HPS performs slightly better than conventional A36 steel.5. The fatigue life prediction methods investigated can predict fatigue test results accurately both for welded and non-welded details. The analytical methods provide a useful tool for classifying the severity of different structural details and can be used to derive fatigue curves for common details made of HPS6. The fatigue resistance of the non-welded HPS details analysed is about one fatigue category higher than those made of conventional structural steels.7. The ductility of HPS 485Wsteel tested under monotonic tension is comparable to the ductility of conventional structural grade steels; 8. One heat of HPS 485W steel used in the test program shows similar upper shelf energy absorption as A7 steel, but has a significantly lower transition temperature.9. Considerable differences in toughness were observed between different heats of HPS.10. The crack initiation properties of a higher toughness HPS (HPS (HT)) are not better than those of the lower toughness HPS (HPS (LT)), nor are the fatigue properties of HPS significantly superior to those of low toughness conventional steels at higher strain amplitudes.11. A comparison of crack propagation properties of HPS and 350WTsteel indicates that HPS behaves similarly to conventional grades of structural steel, although it may be marginally superior; and 6. The HPS 485W steel tested provides a significantly higher fatigue endurance limit for the base material alone than conventional structural steels, providing a potential advantage in high cycle fatigue applications, although the few full-scale tests on particular details that have been conducted to date have indicated that this may not translate into a higher endurance limit for welded details.
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