| Microstructures and mechanical properties of Ti-modified HY180 ultrahigh strength steels have been investigated by means of optical microscopy, energy dispersive X-ray spectrometry, tensile tests, Charpy V-notch impact tests and scanning electron microscopy, and then compared with those of the typical Ti-unmodified HY180 steel. Ti-modificztion refined grain sizes of the HY180 steels and formed Ti and S containing inclusions in the steels. The tensile strength of the HY180 steels was not almost changed(about 1350 MPa) by Ti-modification when Ti content was less than 0.1 wt%. The Charpy V-notch energy absorption increased from 75 J to 145 J by Ti-modification, and this was attributed partly to the grain size refinement. |
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