Mn18Cr18N, the high-nitrogen steel, is the 2nd generation material for manufacturing the retaining ring of firepower generators. In this paper, the hot deformation behavior of the material was investigated by thermo-m...Mn18Cr18N, the high-nitrogen steel, is the 2nd generation material for manufacturing the retaining ring of firepower generators. In this paper, the hot deformation behavior of the material was investigated by thermo-mechanical modeling tests. And the flow stress curves of the steel were obtained for various combinations of the temperature and strain rate. Based on the results of the tests, the complex forming process of a retaining ring including punching, expanding and extrusion with an enclosure was put forward and simulated by means of numerical simulation method. The results indicate that the process is a novel and force-saved practical technology for manufacturing heavy retaining rings.展开更多
The important status of guide ring in large power plants and its manufacturing methods were introduced. The advantages of manufacturing methods including welding and electrolysis were discussed.In order to ensure the ...The important status of guide ring in large power plants and its manufacturing methods were introduced. The advantages of manufacturing methods including welding and electrolysis were discussed.In order to ensure the brazing quality of the guide ring,ultrasonic nondestructive testing(UNDT) method was used in this study.According to the features of the defects that may show up during brazing,the feasibility and reliability of UNDT were proved in theory.Based on the theory,an ultrasonic C-scan imaging test method was developed using a water immersion focusing probe.According to the features of the inspected images,the defects were segmented using a morphology image processing based method.The defects can be localized and sized by employing the algorithm of area reconstruction.At last,the combination ratio of brazing interface can be calculated and the brazing quality of the guide ring can be evaluated.展开更多
Ring calcification in untreated hepatocellular carcinoma(HCC) is extremely rare,with only 3 previously reported cases in the English-language literature.A case of HCC with ring calcification was reported in this paper...Ring calcification in untreated hepatocellular carcinoma(HCC) is extremely rare,with only 3 previously reported cases in the English-language literature.A case of HCC with ring calcification was reported in this paper.Additionally,3 previously reported cases of HCC with ring calcification were reviewed.In 3 of these 4 cases(including our case),surgery was performed.Although the size of the ring-calcified lesion ranged from 3.0-3.7 cm in previously reported cases,the size was only 1 cm in ours.The differentiation of the tumor was moderate in the 2 previously reported cases in the histological findings and poor in ours.In spite of their poor differentiation for their sizes,these tumors showed no early enhancement in dynamic computed tomography.All calcified tumors showed a thick fibrous capsule and extensive necrosis histologically.Ring calcification was considered to result from a circulatory disturbance caused by the imbalance between the less abundant arterial blood flow and high inner pressure induced by either the thick fibrous capsule or vigorous proliferation due to the poor differentiation.Ring calcification in untreated HCC may suggest a lower differentiation of the tumor.Even if its size is small,hepatic resection should be performed for any tumor with ring calcification because poor differentiation is considered to be one of the risk factors for recurrence after local ablation therapy,including radio frequency ablation.展开更多
文摘Mn18Cr18N, the high-nitrogen steel, is the 2nd generation material for manufacturing the retaining ring of firepower generators. In this paper, the hot deformation behavior of the material was investigated by thermo-mechanical modeling tests. And the flow stress curves of the steel were obtained for various combinations of the temperature and strain rate. Based on the results of the tests, the complex forming process of a retaining ring including punching, expanding and extrusion with an enclosure was put forward and simulated by means of numerical simulation method. The results indicate that the process is a novel and force-saved practical technology for manufacturing heavy retaining rings.
基金the Fund of the State Key Laboratory of Advanced Welding and Joining,Harbin Institute of Technology(No.welding 10-013)
文摘The important status of guide ring in large power plants and its manufacturing methods were introduced. The advantages of manufacturing methods including welding and electrolysis were discussed.In order to ensure the brazing quality of the guide ring,ultrasonic nondestructive testing(UNDT) method was used in this study.According to the features of the defects that may show up during brazing,the feasibility and reliability of UNDT were proved in theory.Based on the theory,an ultrasonic C-scan imaging test method was developed using a water immersion focusing probe.According to the features of the inspected images,the defects were segmented using a morphology image processing based method.The defects can be localized and sized by employing the algorithm of area reconstruction.At last,the combination ratio of brazing interface can be calculated and the brazing quality of the guide ring can be evaluated.
文摘Ring calcification in untreated hepatocellular carcinoma(HCC) is extremely rare,with only 3 previously reported cases in the English-language literature.A case of HCC with ring calcification was reported in this paper.Additionally,3 previously reported cases of HCC with ring calcification were reviewed.In 3 of these 4 cases(including our case),surgery was performed.Although the size of the ring-calcified lesion ranged from 3.0-3.7 cm in previously reported cases,the size was only 1 cm in ours.The differentiation of the tumor was moderate in the 2 previously reported cases in the histological findings and poor in ours.In spite of their poor differentiation for their sizes,these tumors showed no early enhancement in dynamic computed tomography.All calcified tumors showed a thick fibrous capsule and extensive necrosis histologically.Ring calcification was considered to result from a circulatory disturbance caused by the imbalance between the less abundant arterial blood flow and high inner pressure induced by either the thick fibrous capsule or vigorous proliferation due to the poor differentiation.Ring calcification in untreated HCC may suggest a lower differentiation of the tumor.Even if its size is small,hepatic resection should be performed for any tumor with ring calcification because poor differentiation is considered to be one of the risk factors for recurrence after local ablation therapy,including radio frequency ablation.
