Tungsten inert gas（TIG） welding was performed on 2.7 mm thick commercial extruded AZ31 B magnesium alloy plates. We investigated the effect of post-weld heat treatment（PWHT） on the microstructure, mechanical prope...Tungsten inert gas（TIG） welding was performed on 2.7 mm thick commercial extruded AZ31 B magnesium alloy plates. We investigated the effect of post-weld heat treatment（PWHT） on the microstructure, mechanical properties and precipitated phase of the weld joints. The results showed that during the annealing treatment（200 ℃-1 h, 250 ℃-1 h, 300 ℃-1 h, 350 ℃-1 h, 400 ℃-1 h, and 450 ℃-1 h）, the average grain size in the weld seam was the minimum after annealing at 400 ℃ for 1 hour, and then abnormally grew up after annealing at 450 ℃ for 1 hour. The mechanical properties enhanced when the joints were processed from 200 ℃-1 h to 400 ℃-1 h but sharply decreased with increasing annealing temperature. In contrast to the annealing treatment, solution treatment（250 ℃-10 h, 300 ℃-10 h, 350 ℃-10 h, 400 ℃-10 h, and 450 ℃-10 h） exhibited a better ductility but a slight deterioration in tensile strength. Especially speaking, no eutectic compounds（such as Mg17 Al12） were observed in the weld seam. The supersaturated Al atoms were precipitated in a coarse spherical shape dispersed in the weld seam. The precipitated Al atoms dissolved in the matrix substances at the condition（400 ℃-1 h） or（250 ℃-10 h）. The solution treatment caused grain coarsening and precipitated Al atoms dissolved in the weld seam substantially, which resulted in a drop in micro-hardness at the weld seam compared to the area of the annealed joints.展开更多
The fatigue property of AZ31 magnesium alloy and its TIG welded joints were investigated. The ultrasonic peening treatment （UPT） was used to improve the fatigue property of the TIG welded joints, which was treated a...The fatigue property of AZ31 magnesium alloy and its TIG welded joints were investigated. The ultrasonic peening treatment （UPT） was used to improve the fatigue property of the TIG welded joints, which was treated at the weld toe by the UPT process. The test results show that the fatigue strength of the base metal of AZ31 magnesium alloys is 57.8 MPa, and those of the fillet joint and the transverse cross joint are respectively 20. 0 MPa and 17.2 MPa at 2 × 10^6 cycles. The fatigue strengths of two kinds of welded joints treated by the UPT are respectively 30. 3 MPa and 24. 7 MPa, which have been improved by 51.5% and 43.6%, respectively. The fatigue life of the fillet joint specimens is prolonged by about 2. 74 times and the fatigue life of the transverse cross joint specimens is prolonged by about 1.05 times when the stress range is at 40. 0 MPa.展开更多
The dissimilar metals 1Crl8Ni9 and 16MnR are welded by shielded metal arc welding process using electrode A312. The corrosion experiments are carried out on welded joint samples, which is as-welded and post-weld heat ...The dissimilar metals 1Crl8Ni9 and 16MnR are welded by shielded metal arc welding process using electrode A312. The corrosion experiments are carried out on welded joint samples, which is as-welded and post-weld heat treatment at 650 ℃, 750 ℃ and 850 ℃, for 2 h in 70% sodium hydroxide solution. EDS and X-ray diffraction analysis are carried out on the samples after corrosion. Average corrosion rate calculation and microhardness measurement are conducted on both as- welded and post-weld heat treatment samples. The results indicate that average corrosion rate of as-welded joint metal is smaller than that of post-weld heat treatment joint metal. Compared with that of post-weld heat treatment at 750 ℃ and 850 ℃ for 2 h, the average corrosion rate of welded joint after post-weld heat treatment at 650 ℃ for 2 h increases greatly.展开更多
BACKGROUND Non-albicans Candida prosthetic joint infections (PJIs) are rare. Optimal treatment involves a two-stage revision surgery in combination with an antifungal agent. However, no clear guidelines have been deve...BACKGROUND Non-albicans Candida prosthetic joint infections (PJIs) are rare. Optimal treatment involves a two-stage revision surgery in combination with an antifungal agent. However, no clear guidelines have been developed regarding the agent or treatment duration. Hence, a broad range of antifungal and surgical treatments have been reported so far. AIM To clarify treatment of non-albicans Candida PJIs. METHODS A literature review of all existing non-albicans Candida PJIs cases through April 2018 was conducted. Information was extracted about demographics, comorbidities, responsible species, duration and type of antifungal treatment, type of surgical treatment, time between initial arthroplasty and symptom onset, time between symptom onset and definite diagnosis, outcome of the infection and follow-up. RESULTS A total of 83 cases, with a mean age of 66.3 years, were located. The causative yeast isolated in most cases was C. parapsilosis (45 cases;54.2%), followed by C. glabrata (18 cases;21.7%). The mean Charlson comorbidity index was 4.4 ± 1.5. The mean time from arthropalsty to symptom onset was 27.2 ± 43 mo, while the mean time from symptom onset to culture-confirmed diagnosis was 7.5 ± 12.5 mo. A two stage revision arthroplasty (TSRA), when compared to one stage revision arthroplasty, had a higher success rate (96% vs 73%, P = 0.023). Fluconazole was the preferred antifungal agent (59;71%), followed by amphotericin B (41;49.4%). CONCLUSION The combination of TSRA and administration of prolonged antifungal therapy after initial resection arthroplasty is suggested on the basis of limited data.展开更多
The surface of 1Cr5 Mo heat-resistant steel welding joint was processed with CO2 laser, and the corrosion behaviors before and after laser heat treatment(LHT) were investigated in the salt spray corrosion environments...The surface of 1Cr5 Mo heat-resistant steel welding joint was processed with CO2 laser, and the corrosion behaviors before and after laser heat treatment(LHT) were investigated in the salt spray corrosion environments. The microstructures, phases, residual stresses and retained austenite content of 1Cr5 Mo steel welding joint before and after LHT were analyzed with optical microscope and X-ray diffraction, respectively. The cracking morphologies and chemical compositions of corrosion products after salt spray corrosion were analyzed with field emission scanning electron microscopy(FESEM) and energy disperse spectroscopy(EDS), respectively, the polarization curves were measured on a PS-268 A type electrochemical workstation, and the mechanism of corrosion resistance by LHT was investigated as well. The results show that the passive film of original sample is destroyed owing to the corrosive media penetrating into the subsurface, resulting in the redox reaction. The content of residual austenite in the surface and the self-corrosion potential are increased by LHT, which is contributed to improving the capability of salt spray corrosion resistance.展开更多
The electron beam local post-weld heat treatment (EBLPWHT) is a rather new method that provides the advantages of high precision, flexibility and efficiency, energy saving and higher productivity. This paper studies t...The electron beam local post-weld heat treatment (EBLPWHT) is a rather new method that provides the advantages of high precision, flexibility and efficiency, energy saving and higher productivity. This paper studies the effect of two post-weld heat treatment processes on the microstructure, mechanical properties and fracture toughness of an electron beam welded joints in 30CrMnSiNi2A steel. EBLPWHT, in a vacuum chamber, immediately after welding and a traditional furnace whole post-weld heat treatment (FWPWHT) were compared. The experimental results show that, after EBLPWHT treatment, the main microstructure of weld was changed from coarse acicular martensite into lath martensite, HAZ was changed from lath martensite, bainite into lower bainite, and base metal was changed from ferrite and pearlite into upper bainite and residual austenite. The microstructures of different zones of joints in FWPWHT condition were tempered sorbite. The properties of welded joints can be improved by the EBLPWHT in some extent, and especially largely for the fracture toughness of welded joints. However the value of fracture toughness of base metal is comparatively low, so appropriate heat treatment parameters should be explored in the future.展开更多
Objective To study the early diagnosis and treatment of pulmonary embolism (PE) after total joint replacement (TJR). Methods From April 1987 to December 2001, we performed 1 336 total knee replacements (TKR) in 926 pa...Objective To study the early diagnosis and treatment of pulmonary embolism (PE) after total joint replacement (TJR). Methods From April 1987 to December 2001, we performed 1 336 total knee replacements (TKR) in 926 patients and 1 745 total hip replacements (RHRs) in 1 566 patients. In this group there were 5 PE patients after operation. Two patients died (all after TKR), and 3 patients salvaged successfully (2 after TKR, 1 after THR). Results The total incidence of PE after TJR was 0. 2% (5/2 492), the incidence of PE after TKR was 0. 4% (4/926), and the incidence of PE after THR was 0.06% (1/1 556). In the patients who suffered PE, 2 died. The incidence of PE before 2000 was 0%. Conclusion Death after total joint replacement is due to pulmonary embolism ( PE), especially massive PE. The incidence of PE after TKR is higher than that after THR. Pulmonary angiography is the gold standard for the diagnosis of PE. With more understanding on PE and more popularity of joint replacement, the diagnosis of PE展开更多
A pipeline steel X80 with welded joint was subjected to surface mechanical attrition treatment （SMAT）. After SMAT, a nanostructure surface layer with an average grain size of about 10 nm was formed in the treated sa...A pipeline steel X80 with welded joint was subjected to surface mechanical attrition treatment （SMAT）. After SMAT, a nanostructure surface layer with an average grain size of about 10 nm was formed in the treated sample, and the fatigue limit of the welded joint was elevated by about 13% relative to the untreated joints. In the low and the high amplitude stress regimes, both fatigue strength and fatigue life were enhanced. Formation of the nanostructured surface layer played more important role in the enhanced fatigue behavior than that of residual stress induced by the SMAT.展开更多
With the development of an IT (Information Technology) society, the opportunity to use electronic devices, such as cell phones and personal computers, has increased. These electronic devices pro-vide many benefits to ...With the development of an IT (Information Technology) society, the opportunity to use electronic devices, such as cell phones and personal computers, has increased. These electronic devices pro-vide many benefits to society. However, there have been a number of reports of electromagnetic hypersensitivity (EHS) related to the use of electronic devices. The symptoms of EHS may include headaches, fatigue, tinnitus, dizziness, memory loss, irregular heartbeat, and skin trouble. Since the pathogenic mechanism of such conditions is not yet clear, further research is required. This report shows how a subject’s dizziness and joint mobility disorder, caused by electromagnetic waves emitted by electronic devices, were cured by removing an onlay from the patient’s mouth and replacing it with a gold alloy onlay. The result indicates that the subject’s symptoms were caused by EHS. Although the symptoms were improved after the dental treatment, the underlying mechanism of the symptoms and the reason why this treatment is successful remain unclear. Further research is required to clarify these issues.展开更多
Improvement of the fatigue life of welded tubular T-joints in offshore platforms due to weld toe grinding and TIG dressing is studied physically and experimentally. It is shown that the two methods of treatment can im...Improvement of the fatigue life of welded tubular T-joints in offshore platforms due to weld toe grinding and TIG dressing is studied physically and experimentally. It is shown that the two methods of treatment can improve the fatigue strength of welded tubular joints not only in the environment of air but even in the envirnment of seawater accordingly.展开更多
基金Funded by the National Natural Science Foundation of China(Nos.51505322,51175364)Natural Science Foundation of Shanxi Province of China(No.2013011014-3)
文摘Tungsten inert gas（TIG） welding was performed on 2.7 mm thick commercial extruded AZ31 B magnesium alloy plates. We investigated the effect of post-weld heat treatment（PWHT） on the microstructure, mechanical properties and precipitated phase of the weld joints. The results showed that during the annealing treatment（200 ℃-1 h, 250 ℃-1 h, 300 ℃-1 h, 350 ℃-1 h, 400 ℃-1 h, and 450 ℃-1 h）, the average grain size in the weld seam was the minimum after annealing at 400 ℃ for 1 hour, and then abnormally grew up after annealing at 450 ℃ for 1 hour. The mechanical properties enhanced when the joints were processed from 200 ℃-1 h to 400 ℃-1 h but sharply decreased with increasing annealing temperature. In contrast to the annealing treatment, solution treatment（250 ℃-10 h, 300 ℃-10 h, 350 ℃-10 h, 400 ℃-10 h, and 450 ℃-10 h） exhibited a better ductility but a slight deterioration in tensile strength. Especially speaking, no eutectic compounds（such as Mg17 Al12） were observed in the weld seam. The supersaturated Al atoms were precipitated in a coarse spherical shape dispersed in the weld seam. The precipitated Al atoms dissolved in the matrix substances at the condition（400 ℃-1 h） or（250 ℃-10 h）. The solution treatment caused grain coarsening and precipitated Al atoms dissolved in the weld seam substantially, which resulted in a drop in micro-hardness at the weld seam compared to the area of the annealed joints.
基金the National Natural Science Foundation of China (No.50675148)
文摘The fatigue property of AZ31 magnesium alloy and its TIG welded joints were investigated. The ultrasonic peening treatment （UPT） was used to improve the fatigue property of the TIG welded joints, which was treated at the weld toe by the UPT process. The test results show that the fatigue strength of the base metal of AZ31 magnesium alloys is 57.8 MPa, and those of the fillet joint and the transverse cross joint are respectively 20. 0 MPa and 17.2 MPa at 2 × 10^6 cycles. The fatigue strengths of two kinds of welded joints treated by the UPT are respectively 30. 3 MPa and 24. 7 MPa, which have been improved by 51.5% and 43.6%, respectively. The fatigue life of the fillet joint specimens is prolonged by about 2. 74 times and the fatigue life of the transverse cross joint specimens is prolonged by about 1.05 times when the stress range is at 40. 0 MPa.
文摘The dissimilar metals 1Crl8Ni9 and 16MnR are welded by shielded metal arc welding process using electrode A312. The corrosion experiments are carried out on welded joint samples, which is as-welded and post-weld heat treatment at 650 ℃, 750 ℃ and 850 ℃, for 2 h in 70% sodium hydroxide solution. EDS and X-ray diffraction analysis are carried out on the samples after corrosion. Average corrosion rate calculation and microhardness measurement are conducted on both as- welded and post-weld heat treatment samples. The results indicate that average corrosion rate of as-welded joint metal is smaller than that of post-weld heat treatment joint metal. Compared with that of post-weld heat treatment at 750 ℃ and 850 ℃ for 2 h, the average corrosion rate of welded joint after post-weld heat treatment at 650 ℃ for 2 h increases greatly.
文摘BACKGROUND Non-albicans Candida prosthetic joint infections (PJIs) are rare. Optimal treatment involves a two-stage revision surgery in combination with an antifungal agent. However, no clear guidelines have been developed regarding the agent or treatment duration. Hence, a broad range of antifungal and surgical treatments have been reported so far. AIM To clarify treatment of non-albicans Candida PJIs. METHODS A literature review of all existing non-albicans Candida PJIs cases through April 2018 was conducted. Information was extracted about demographics, comorbidities, responsible species, duration and type of antifungal treatment, type of surgical treatment, time between initial arthroplasty and symptom onset, time between symptom onset and definite diagnosis, outcome of the infection and follow-up. RESULTS A total of 83 cases, with a mean age of 66.3 years, were located. The causative yeast isolated in most cases was C. parapsilosis (45 cases;54.2%), followed by C. glabrata (18 cases;21.7%). The mean Charlson comorbidity index was 4.4 ± 1.5. The mean time from arthropalsty to symptom onset was 27.2 ± 43 mo, while the mean time from symptom onset to culture-confirmed diagnosis was 7.5 ± 12.5 mo. A two stage revision arthroplasty (TSRA), when compared to one stage revision arthroplasty, had a higher success rate (96% vs 73%, P = 0.023). Fluconazole was the preferred antifungal agent (59;71%), followed by amphotericin B (41;49.4%). CONCLUSION The combination of TSRA and administration of prolonged antifungal therapy after initial resection arthroplasty is suggested on the basis of limited data.
基金Project(CXLX14-1098)supported by Jiangsu Province Postgraduate Scientific Research Innovation Program,China
文摘The surface of 1Cr5 Mo heat-resistant steel welding joint was processed with CO2 laser, and the corrosion behaviors before and after laser heat treatment(LHT) were investigated in the salt spray corrosion environments. The microstructures, phases, residual stresses and retained austenite content of 1Cr5 Mo steel welding joint before and after LHT were analyzed with optical microscope and X-ray diffraction, respectively. The cracking morphologies and chemical compositions of corrosion products after salt spray corrosion were analyzed with field emission scanning electron microscopy(FESEM) and energy disperse spectroscopy(EDS), respectively, the polarization curves were measured on a PS-268 A type electrochemical workstation, and the mechanism of corrosion resistance by LHT was investigated as well. The results show that the passive film of original sample is destroyed owing to the corrosive media penetrating into the subsurface, resulting in the redox reaction. The content of residual austenite in the surface and the self-corrosion potential are increased by LHT, which is contributed to improving the capability of salt spray corrosion resistance.
文摘The electron beam local post-weld heat treatment (EBLPWHT) is a rather new method that provides the advantages of high precision, flexibility and efficiency, energy saving and higher productivity. This paper studies the effect of two post-weld heat treatment processes on the microstructure, mechanical properties and fracture toughness of an electron beam welded joints in 30CrMnSiNi2A steel. EBLPWHT, in a vacuum chamber, immediately after welding and a traditional furnace whole post-weld heat treatment (FWPWHT) were compared. The experimental results show that, after EBLPWHT treatment, the main microstructure of weld was changed from coarse acicular martensite into lath martensite, HAZ was changed from lath martensite, bainite into lower bainite, and base metal was changed from ferrite and pearlite into upper bainite and residual austenite. The microstructures of different zones of joints in FWPWHT condition were tempered sorbite. The properties of welded joints can be improved by the EBLPWHT in some extent, and especially largely for the fracture toughness of welded joints. However the value of fracture toughness of base metal is comparatively low, so appropriate heat treatment parameters should be explored in the future.
文摘Objective To study the early diagnosis and treatment of pulmonary embolism (PE) after total joint replacement (TJR). Methods From April 1987 to December 2001, we performed 1 336 total knee replacements (TKR) in 926 patients and 1 745 total hip replacements (RHRs) in 1 566 patients. In this group there were 5 PE patients after operation. Two patients died (all after TKR), and 3 patients salvaged successfully (2 after TKR, 1 after THR). Results The total incidence of PE after TJR was 0. 2% (5/2 492), the incidence of PE after TKR was 0. 4% (4/926), and the incidence of PE after THR was 0.06% (1/1 556). In the patients who suffered PE, 2 died. The incidence of PE before 2000 was 0%. Conclusion Death after total joint replacement is due to pulmonary embolism ( PE), especially massive PE. The incidence of PE after TKR is higher than that after THR. Pulmonary angiography is the gold standard for the diagnosis of PE. With more understanding on PE and more popularity of joint replacement, the diagnosis of PE
基金supported by the CNPC (China National Petroleum Corporation) Innovation Foundation under grant No.07E1015
文摘A pipeline steel X80 with welded joint was subjected to surface mechanical attrition treatment （SMAT）. After SMAT, a nanostructure surface layer with an average grain size of about 10 nm was formed in the treated sample, and the fatigue limit of the welded joint was elevated by about 13% relative to the untreated joints. In the low and the high amplitude stress regimes, both fatigue strength and fatigue life were enhanced. Formation of the nanostructured surface layer played more important role in the enhanced fatigue behavior than that of residual stress induced by the SMAT.
文摘With the development of an IT (Information Technology) society, the opportunity to use electronic devices, such as cell phones and personal computers, has increased. These electronic devices pro-vide many benefits to society. However, there have been a number of reports of electromagnetic hypersensitivity (EHS) related to the use of electronic devices. The symptoms of EHS may include headaches, fatigue, tinnitus, dizziness, memory loss, irregular heartbeat, and skin trouble. Since the pathogenic mechanism of such conditions is not yet clear, further research is required. This report shows how a subject’s dizziness and joint mobility disorder, caused by electromagnetic waves emitted by electronic devices, were cured by removing an onlay from the patient’s mouth and replacing it with a gold alloy onlay. The result indicates that the subject’s symptoms were caused by EHS. Although the symptoms were improved after the dental treatment, the underlying mechanism of the symptoms and the reason why this treatment is successful remain unclear. Further research is required to clarify these issues.
文摘Improvement of the fatigue life of welded tubular T-joints in offshore platforms due to weld toe grinding and TIG dressing is studied physically and experimentally. It is shown that the two methods of treatment can improve the fatigue strength of welded tubular joints not only in the environment of air but even in the envirnment of seawater accordingly.
