Effect of Post-weld Heat Treatment on Mechanical Characteristics of AZ31 Magnesium Alloy Welded Joints

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.

Improving the fatigue property of welded joints for AZ31 magnesium alloy by ultrasonic peening treatment

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.

Effect of heat treatment temperature on dissimilar welded joint

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.

Surface grain refinement mechanism of SMA490BW steel cross joints by ultrasonic impact treatment

Ultrasonic impact treatment (UIT) is a postweld technique for improving the fatigue strength of welded joints. This technique makes use of ultrasonic vibration to impact and plastically deform a weld toe and can achieve surface grain refinement of the weld toe, which is considered as the main reason for the improvement of fatigue strength. In this paper, the microstructure of the surface of a treated weld toe was observed by metallographic microscopy and transmission electron microscopy (TEM). The results show that UIT could produce severe plastic deformation on the surface layer of the weld toe and the maximum depth of plastic deformation extended to approximately 260 μm beneath the treated surface. Repeated processing could exacerbate the plastic deformation on the surface layer, resulting in finer grains. We can conclude that the surface grain refinement mechanism of SMA490BW welded joints is related to the high density of dislocation tangles and dislocation walls. © 2017, University of Science and Technology Beijing and Springer-Verlag Berlin Heidelberg.

Non-albicans Candida prosthetic joint infections: A systematic review of treatment

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.

Effect of Post-weld Heat Treatment on Microstructure and Fracture Toughness of 30CrMnSiNi2A Steel Welded Joints

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.

Early diagnosis and treatment of pulmonary embolism after total joint replacement: report of five cases

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

Improved Fatigue Behavior of Pipeline Steel Welded Joint by Surface Mechanical Attrition Treatment(SMAT)

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.

Dental Treatment for Dizziness and Joint Mobility Disorder Caused by Harmful Electromagnetic Waves

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.

IMPROVEMENT OF FATIGUE STRENGTH OF TUBULAR T-JOINT IN OFFSHORE PLATFORMS DUE TO POSTWELD TREATMENT

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.

Tuberculosis Arthritis of the Sternoclavicular Joint

Tuberculosis remains a public health problem in developing country particularly in Tunisia. Bone location of tuberculosis infection is increasing and is often misdiagnosed due to the weakness of clinical presentation in early stages. Sternoclavicular joint tuberculosis is rare and unusual location of this disease. However, antibiotherapy and surgical debridement is still the basis of treatment. We report a case of sternoclavicular joint tuberculosis with a follow up of four years. The patient was treated surgically and put under antibiotherapy during twelve months. The site was sterilized. We report this case to show that debridement and antibiotherapy still efficient in tuberculous bone affection no matters the location.

Management of Traumatic Joint Dislocations in Irrua

Aim:?To elucidate the pattern of presentation and management of traumatic major joint dislocations as seen in Irrua Specialist Teaching Hospital. Method: A five-year retrospective review of 44 cases in 43 patients. Data were retrieved from the Medical Records Department of the hospital. Results:?Forty-four cases of traumatic dislocations were reviewed in 43 patients. Male to female ratio was 7.6:1. Median age was 33 years. The majority of patients were in the 3rd?decade of life. Patients below 40 years accounted for 62.79% of cases. Twenty-four (55.81%) patients had hip dislocation. Knee dislocations were the least, accounting for 2.32% of cases. All cases except three resulted from road traffic accidents (RTAs). None had neurologic deficits. Nineteen (44.23%) patients had isolated injuries. 76.7% cases presented in less than 6 hours. All shoulder dislocations were anterior while all elbow dislocations were posterior. All except 3 cases were managed by closed manipulation under general anaesthesia. Two patients died from associated head injury. Fourteen patients discharged against medical advice while recuperating in the ward. Follow-up was however difficult as a significant number did not turn up. Conclusion: Hip dislocation is the commonest variety of traumatic dislocation in our setting. A majority of cases were amenable to closed manipulation and immobilization. Road traffic accidents accounted for the majority.

Hallux rigidus: Joint preserving alternatives to arthrodesis- a review of the literature

Hallux rigidus describes the osteoarthritis of the firstmetatarsophalangeal joint. It was first mentioned in 1887. Since then a multitude of terms have been introduced referring to the same disease. The main complaints are pain especially during movement and a limited range of motion. Radiographically the typical signs of osteoarthritis can be observed starting at the dorsal portion of the joint. Numerous classifications make the comparison of the different studies difficult. If non-operative treatment fails to resolve the symptoms operative treatment is indicated. The most studied procedure with reproducible results is the arthrodesis. Nevertheless, many patients refuse this treatment option, favouring a procedure preserving motion. Different motion preserving and joint sacrificing operations such as arthroplasty are available. In this review we focus on motion and joint preserving procedures. Numer-ous joint preserving osteotomies have been described. Most of them try to relocate the viable plantar cartilage more dorsally, to decompress the joint and to increase dorsiflexion of the first metatarsal bone. Multiple studies are available investigating these procedures. Most of them suffer from low quality, short follow up and small patient numbers. Consequently the grade of recommendation is low. Nonetheless, joint preserving procedures are appealing because if they fail to relief the symptoms an arthrodesis or arthroplasty can still be performed thereafter.

Prosthetic joint infections-a clinico-microbiological perspective: Review article

Prosthetic joint infections(PJIs),although not very common,currently pose a very significant threat since they are associated with severe complications,high morbidity rates and substantial costs.PJIs are most commonly caused by Staphylococcus aureus and coagulase-negative staphylococci.The diagnosis of implant-associated infections is very challenging since no single routinely used laboratory or clinical test has been shown to demonstrate adequate results with respect to sensitivity,specificity and accuracy.In most cases,a sum of clinical signs and symptoms,histopathology,blood tests,radiography,bone scans and microbiological testing is considered to arrive at an accurate diagnosis.Treatment of PJIs is also very difficult since most of the infections are caused by biofilm-producing microorganisms which are significantly more resistant to the hosts natural defense mechanisms and antibiotic treatment.For successful management,a combination of both antibiotic and surgical treatment is most often required,and early diagnosis is of the utmost importance.Thus,a multidisciplinary approach is potentially the best option in dealing with PJI,and should include the involvement of microbiologists,orthopedic specialists,clinicians,pathologists and radiologists in order to improve decision-making processes and ensure overall success.The following review aims at briefly outlining the microbiology,diagnostic and treatment options,and preventive measures associated with such infections.

Hip Joint Osteoarthritis Pain Sources and Control

Hip joint osteoarthritis, a widespread disabling disease with no known cause, produces considerable bouts of intractable pain as a result of multiple disease associated problems. This paper examines some sources of osteoarthritic hip joint pain, a poorly understood topic at best. Presented in three parts are data retrieved from several sources, including animal models. It is concluded that to improve the effectiveness of treatments designed to minimize hip osteoarthritis pain, a better understanding of the diverse origins of hip joint pain, and hip joint neurology, may permit the development of more precise as well as targeted pain strategies.

Improving fatigue performance of welded joints of X65 pipeline steel by UIT

Treating weld toes properly can improve the fatigue performance. Ultrasonic impact treatment （UIT） is a more effective and convenient method to enhance the fatigue strength of welded joints and suchlike structures. Fatigue tests were conducted on the specimens made of X65 pipeline steel. The test specimens were investigated on the fatigue strength and the fatigue life at the same stress range level by comparing the ones peened by UIT with the others without the treatment： the fatigue strength of the specimens as UIT, 90% of the fatigue strength of the base mental, is increased by 38% compared with that of as welded only; the fatigue life of the ones as UIT is prolonged by 11 multiples of the ones as welded only.

络合沉淀法—硫化沉淀法联合处理铜氰贫液试验研究

针对某黄金生产企业产生的铜氰贫液,采用络合沉淀法—硫化沉淀法联合进行回收处理。在络合沉淀法五水合硫酸铜投加量3.0 g/L、焦亚硫酸钠投加量2.0 g/L,硫化沉淀法九水合硫化钠加药量0.35 g/L条件下,铜氰贫液中总氰化合物、铜和硫氰酸盐质量浓度从150.84 mg/L、121.46 mg/L、252.65 mg/L降至0.44 mg/L、86.17 mg/L、1.23 mg/L,回收金、银、铜的产值为116.62元/m^(3),扣除药剂成本后产生经济效益55.44元/m^(3)。研究结果为类似氰化企业铜氰贫液的净化处理提供参考。

热处理对9Ni钢焊接接头组织和性能的影响

针对运输船用9Ni钢,明晰9Ni钢焊接接头在低温下的塑韧性恶化机理。经手工电弧焊加工后,研究热处理工艺对9Ni钢焊接接头组织和性能的影响规律。结果表明:经调质(QT)热处理后,接头热影响区逆转奥氏体一般分散在晶界周围,马氏体板条界上也有析出的趋势,但和晶界分布相比其含量极少;相比QT热处理,经过两相区(QLT)工艺后接头热影响区的逆转奥氏体数量增加许多,弥散分布在各种晶界处且晶粒更加细小;熔合区的组织更加细小,更加弥散,板条马氏体更明显,方向性更好,主要是L阶段有一定的细化晶粒作用;接头焊缝的冲击吸收能量增加更多,QLT可以让焊缝低温韧性提升更多;两种热处理工艺下冲击断口都为典型的韧窝型断口。

应用阴阳锉跖趾关节成形治疗Freiberg病的临床研究

目的 探讨应用阴阳锉辅助进行跖趾关节成形配合间质填充治疗Freiberg病的临床疗效。方法 选取2019年8月至2023年9月郑州市骨科医院收治的30例Freiberg病患者。其中,男6例,女24例;年龄17~45岁,平均(26.5±6.8)岁。根据Smillie分期:Ⅲ期13例,Ⅳ期9例,Ⅴ期8例。均采用阴阳锉辅助进行跖趾关节成形配合间质填充治疗。术后采用AOFAS评分系统及跖趾关节屈伸活动度进行评价手术效果。结果 所有患者均获得随访,随访时间6~36个月,平均(26.5±13.9)个月。所有患者伤口均Ⅰ期愈合;AOFAS评分由术前(55.3±6.2)分提高到术后6个月的(90.8±5.9)分,差异有统计学意义(P<0.05),所有患者症状得到明显改变;跖趾关节活动度术前跖屈(20.3±5.3)°、背伸(15.2±5.6)°与术后6个月随访测量跖屈(18.9±5.1)°、背伸(14.1±5.2)°相比较,差异无统计学意义(P>0.05)。结论 采用阴阳锉辅助进行跖趾关节成形配合间质填充来治疗该疾病,该术式创伤小,操作简单,既减轻的疼痛症状,又保留了跖趾关节的外形及活动度,改善了患者的生活质量,是较为可靠的一种治疗方案,值得推广应用。