Tensile deformation behavior of high strength anti-seismic steel with multi-phase microstructure

To investigate the tensile deformation behavior of high strength anti-seismic steel with multi-phase microstructure,tensile tests with strains of 0.05,0.12 and 0.22 were performed at room temperature.Microstructure of tested steels was observed by means of optical microscopy（OM）,transmission electron microscopy（TEM）and scanning electron microscopy（SEM）.Tensile mechanical properties of tested steels were obtained,and the influence of bainite content on deformation behavior was also discussed.Meanwhile,the deformation mechanism of steel with three kinds of microstructures of bainite,pearlite and ferrite was analyzed.Results show that tested steel with high volume fraction of bainite exhibits a continuous deformation behavior,and this may be attributed to a higher bainite volume fraction and a lower mobile dislocation density.The morphology of microstructure will influence the mechanical properties of tested steels.An increasing content of bainite can improve the tensile strength,but reduce the plasticity and toughness of the tested steels.In the deformation process of 0.039 Nb steel,the ferrite and bainite have priorities to deform,and the deformation exhibits co-deformation of all microstructures in the later stage of deformation.In the deformation process of 0.024Nb-0.032 Vsteel,the ferrite and pearlite have priorities to deform,and the deformation exhibits co-deformation of all microstructures in the later stage of deformation.

Effect of Zr on undissolved phases and carbide precipitation in Ti microalloyed low-carbon steel

The undissolved phases and carbide precipitation in Ti and Ti-Zr microalloyed low-carbon steels were investigated by scanning electron microscopy, transmission electron microscopy and energy-dispersive X-ray spectrometry. At 1225℃, the replacement of Ti by Zr formed Zr2CS and (Zr, Ti)N (the Ti/Zr atomic ratio is 0.11) and reduced the consumption of Ti. At 925℃, it was identified that TiC phases were precipitated at first and Zr was incorporated into the TiC lattice in the subsequent precipitation process, which promoted the precipitation of titanium carbide. The calculation of the interaction coefficient between Ti, C, N and Zr showed that Zr reduced the activity of Ti and C and increased the activity of N in the iron matrix. Therefore, with the addition of Zr, the solubility of Ti was increased, and the consumption of Ti was reduced at high temperature in Ti microalloyed low-carbon steel. The thermodynamic calculation of carbide precipitation transformation showed that the replacement of Ti by Zr increased the nucleation driving force and the nucleation rate of titanium carbide, while the critical core size and the critical nuclear energy were reduced. As the holding time was extended, the Zr/ Ti atomic ratio increased and the size of the precipitates also increased. When the Zr/Ti atomic ratio reached a certain level, the size of the precipitates did not increase with further increase in atomic ratio. When the Zr/Ti atomic ratio in (Ti, Zr)C was 0.05-0.17,(Ti, Zr)C was the most stable carbide and the easiest to nucleate at 925℃. There was more of the (Ti, Zr)C phase than TiC at 925 ℃ after 50 and 100 s, and the time to complete the coarsening behavior of (Ti, Zr)C was shorter than that of TiC.

Unusual presentation of urachal adenocarcinoma with genitourinary cutaneous metastasis

Dear Editor, The urachus, which is a vestigial structure between the dome of the bladder and umbilicus, usually, retracts from the bladder before birth. However, the urachal remnant was continuous with the bladder cavity even in adults in 32% of bladder in one autopsy study.1 For this reason, tumors may develop from the remnants, most of which are well-differentiated mucinous adenocarcinomas, which is a rare form of vesical malignancy, accounting for 〈 1% of all bladder cancers. Although local spread to the peritoneum is common at presentation, distant metastases without local recurrence are rarely detected following surgical excision of clinically localized disease. To the best of our knowledge,