Treatment of Clavicular Nonunions with Shape Memory Ni-Ti Alloy Swan-Like Bone Connector

Disability caused by nonunited fracture of the clavicle is a rare condition that is expressed by local pain. This condition is usually treated by reduction of the fracture and stable fixation with augmentation by autogenous bone graft. This is a retrospective study to assess outcome of the treatment of clavicular nonunion with a novel shape memory Ni-Ti alloy swan-like bone connector (SMC). August, 2003 to December, 2006, 5 consecutive patients with clavicular nonunion were treated using SMC in our hospital. The SMC device was cooled with ice before implantation and then warmed to 40-50 °C after implantation, to produce balanced axial and compression forces that would stabilize the fracture. We have used cancellous bone grafting in all our cases to obtain solid healing. Average follow-up was 37 months (range 25-58). In all patients, satisfactory osseous union was achieved. There was no complication from the hardware. The average Constant score which is for evaluating function of injured shoulder after operation was 86 points (average Constant score for the unaffected shoulder was 95). All patients were very satisfied with the treatment and outcome. The SMC provides a new effective method for fracture fixation and treatment of bone nonunion for clavicle.     

Swan-like Memory Compressive Connector

Nonunion is a common complication after fractures of the diaphysis of the upper extremity. Conventional internal fixation cannot provide compressive stress at the fracture site, which is critical for fracture repair in nonweight-bearing bones. In order to overcome this problem, we developed a novel nitinol device that provides initial and continuous compression and three dimensional fixation, the swan-like memory compressive connector (SMC). A total of 188 cases (243 bones) of fractures and nonunions were treated by SMC over the course of 16 years. At follow-up, the nonunion sites were bridged by plate-like bone in 92 cases (106 bones) at an average of 3.8 months after surgery. In the fracture group, the fracture sites were bridged by plate-like bone in 93 cases (134 bones) at an average of 2.6 months after surgery. No infection or re-fracture occurred after removal of the SMC. There was no persistent joint dysfunction caused by the SMC.     

Expression of TGF-�� in Fractures Fixed by Nitinol Swan-like Memory Compressive Connectors

In this article, the effect of internal fixation of a Nitinol swan-like memory compressive connector (SMC) on the temporal expression of transforming growth factor-?? (TGF-??) at fracture sites is evaluated. Specimens were collected from 35 New Zealand rabbits modeled for bilateral humeral fracture fixed with either SMC or stainless dynamic compression plate (DCP). Five rabbits each were killed at day 1, 3, 7, 14, 21, 28, and 56. The local positive staining potency, positive area ratio, and positive index of TGF-?? were measured using an immunohistochemistry approach (EnVision) in combination with a computerized image analysis system. TGF-?? staining was seen in mesenchymal cells, osteoblasts, chondrocytes, and in the extracellular matrix of fractures fixed in both the SMC and the DCP samples without a significant difference in staining at both the early stages (days 1 and 3) and day 56. A higher TGF-?? content was observed in the fractures fixed with SMC when compared to that of DCP from day 7 to 28. As a conclusion, TGF-?? is highly expressed in fractures fixed with SMC during chondrogenesis stage and entochondrostosis stage. Finally, the mechanism of how SMC promoting synthesis and secretion of TGF-?? in the process of fracture healing has been discussed.     

Effect of submicrocrystalline state on strength and impact toughness of low-carbon 12GBA steel

The effect of intense warm deformation on the structure and mechanical properties of low-carbon 12GBA steel was investigated. A submicrocrystalline (SMC) structure with an average element size of 0.3 ??m was formed in the steel by isothermal overall forging. The formation of the SMC structure resulted in a sharp increase in strength by a factor of two to three in relation to the initial coarse-grained state while retaining a sufficient level of plasticity and impact toughness. After further annealing, steels exhibit an improved set of properties; i.e., as the strength decreases slightly, the plasticity increases sharply. Impact tests at low temperatures have shown the significant advantage of the SMC state of the steel over the coarse-grained state in the impact toughness. It is established that the cold resistance in the SMC state increases because the crack propagation prevails in the overall sample fracture.     

仙灵骨葆联合益生菌对骨质疏松性骨折大鼠的愈合作用

目的: 研究仙灵骨葆联合益生菌对骨质疏松性骨折大鼠的愈合作用。方法: 将雌性SD大鼠50只随机分成5组，分别为常规骨折对照组、骨质疏松性骨折模型组、仙灵骨葆组、益生菌组、仙灵骨葆联合益生菌组，每组10只。除常规骨折对照组外，其余均切除双侧卵巢制备骨质疏松模型。6周后，每组均制备右侧股骨中段横型骨折模型。然后分别灌胃给予生理盐水、仙灵骨葆（250 mg·kg^-1·d^-1）及益生菌（12.5 g·kg^-1·d^-1）。术后5周取各组右侧股骨标本，骨密度仪测量骨密度，CR摄片和Micro-CT扫描观察股骨相关参数。酶联免疫法测定大鼠血清骨源性碱性磷酸酶（BALP）、抗酒石酸酸性磷酸酶（TRACP），显色法测定钙浓度（Ca），HE染色观察骨折骨膜组织病理变化。结果: 与骨质疏松性骨折组比较，给予仙灵骨葆或益生菌组的BALP水平增高，TRACP水平降低，骨密度和骨痂量增多，骨折线模糊，骨小梁数量和厚度增加，骨小梁间隔降低，而仙灵骨葆联合益生菌组作用最明显（P<0.05，P<0.01）。结论: 益生菌和仙灵骨葆均有促进骨质疏松性骨折愈合的治疗作用，联合用药有更佳效果。     

焊后回火温度对G115钢熔敷金属组织及室温力学性能的影响

采用G115钢焊条焊接了熔敷金属试板,然后分别在760、780、800、820 ℃下进行了焊后回火热处理,并对不同回火温度下试样的力学性能和显微组织进行了分析。结果表明,G115钢熔敷金属的最佳回火温度为800 ℃,随着回火温度的升高,析出相M₂₃C₆有长大的趋势。760~820 ℃回火后的冲击断口表现为韧窝断裂和准解理断裂特征,在韧窝内存在焊接冶金脱氧过程中形成的球形第二相粒子。     

Influence of slab reheating practice on the microstructural evolution and toughness behavior of quenched and tempered plates of medium carbon microalloyed steel

In the current study, granular bainite was found to be the major component in the microstructure of air cooled 80 mm thick plates of medium carbon microalloyed steel. The second constituent in this granular bainite was identified as cementite. It was further observed that (1) ferrite lath size and (2) amount of cementite in granular bainite varied with slab reheating time before plate rolling. Smaller ferrite laths and a lesser amount of cementite were found in the plate processed with the longer slab reheating time of 26 h. Contrary to this, very large sized ferrite laths and a larger population of cementite were formed in the plate processed with the shorter slab reheating time of 4 h. Subsequent quenching and tempering of these plates favored the formation of lower bainite and tempered martensite in the plate with 26 h slab reheating time. On the other hand, upper bainite and coarser cementite were formed after the quenching and tempering of the plate with 4 h of slab reheating time. The influence of different microstructures, formed due to varied slab reheating time, on the toughness property of tempered plates was evaluated under different test conditions. In tensile test and fracture toughness testing of thinner specimens, a ductile mode of fracture was observed, irrespective of varied microstructures in the tempered plates. However, in the three-point bend test of full thickness specimens, the mode of fracture was ductile in the tempered plate with 26 h slab reheating time, while the tempered plate from the slab with 4 h reheating time gave rise to a predominantly brittle mode of fracture. These observations showed that the toughness property of these tempered plates was sensitive to the microstructure only under the specific condition, which prevailed during the three-point bend test of full thickness specimens. Under this condition, coarse cementite and upper bainite became prone to cracking resulting in a lower toughness of the tempered plate associated with lower slab reheating time.     

Design and Clinical Application of Proximal Humerus Memory Connector

Treatment for comminuted proximal humerus fractures and nonunions are a substantial challenge for orthopedic surgeons. Plate and screw fixation does not provide enough stability to allow patients to begin functional exercises early after surgery. Using shape memory material nickel titanium alloy, we designed a new device for treating severe comminuted proximal humerus fractures that accommodates for the anatomical features of the proximal humerus. Twenty-two cases of comminuted fracture, malunion, and nonunion of the proximal humerus were treated with the proximal humeral memory connector (PHMC). No external fixation was needed after the operation and patients began active shoulder exercises an average of 8 days after the operation. Follow-up evaluation (mean 18.5 months) revealed that bone healing with lamellar bone formation occurred an average of 3.6 months after surgery for the fracture cases and 4.5 months after surgery for the nonunion cases. Average shoulder function was 88.5 according to the criteria of Michael Reese. PHMC is an effective new device to treat comminuted proximal humerus fractures and nonunions. The use of this device may reduce the need for shoulder joint arthroplasty.     

减压塔顶板式空冷器腐蚀失效分析及建议

利用宏观形貌观察、化学成分分析、金相观察和X射线衍射等方法,分析了某石化公司减压塔顶预冷板式空冷器的腐蚀失效原因.采用电化学测试对常用不锈钢在3.5% NaCl溶液和减顶冷凝水中的腐蚀性能进行对比研究.结果表明,316L不锈钢材料合格,预冷板式空冷器板束腐蚀失效是由于冷却水垢下腐蚀造成的.304和316L不锈钢均在减顶...     

B级钢/Q450NQR1钢搭接接头疲劳性能研究

针对以Q450NQR1钢(中梁)为基板、B级钢(上心盘)为腹板模拟实际工装位置,疲劳断裂与货车运营实际工况不符的问题,提出以B级钢为基板、Q450NQR1钢为腹板进行三点弯曲疲劳试验,诱使疲劳裂纹向B级钢侧扩展,研究了MAG气体保护焊B级钢/Q450NQR1钢搭接接头的疲劳性能。结果表明:B级钢/Q450NQR1钢搭接接头的疲劳裂纹多出现在B级钢侧,与货车运营的实际工况相符。在循环次数2×106、存活率95%、置信水平90%时,搭接接头焊态、打磨态、喷丸态的疲劳强度分别为201.89、225.36、232.69MPa;表面机械打磨、喷丸工艺能够较好改善B级钢/Q450NQR1钢搭接接头的疲劳性能。     

Biomechanical Study of Acetabular Tridimensional Memoryalloy Fixation System

We developed the acetabular tridimensional memoryalloy fixation system (ATMFS), which is made of NiTi shape memory alloy, according to the specific mechanical properties of biological memory material, NiTi shape memory alloy and measured distribution of contact area and pressure between the acetabulum and the femoral head of cadaveric pelvis. Seven formalin-preserved cadaveric pelves were used for this investigation. Pressure-sensitive film was used to measure contact area and pressure within the anterior, superior, and posterior regions of the acetabulum. The pelves were loaded under the following four conditions: (1) intact; (2) following a creation posterior wall fracture defect; (3) following reduction and standard internal fixation with reconstruction plate; and (4) following reduction and internal fixation with a new shape memory alloy device named ATMFS. A posterior wall fracture was created along an arc of 40° to 90° about the acetabulur rim. Creation of a posterior wall defect resulted in increased load in the superior acetabulum (1485 N) as compared to the intact condition (748 N, P = 0.009). Following reduction and internal fixation, the load distributed to the superior acetabulum (1545 N) was not statistically different from the defect condition. Following the fixation with ATMFS, the load seen at the superior region of the actabulum (964 N) was familiar with fixation with reconstruction plate and was not different from intact state (P = 0.45). These data indicate that the use of ATMFS as a fracture internal fixation device resulted a partial restoration of joint loading parameters toward the intact state. ATMFS fixation may result in a clinical benefit.     

亚温淬火对09MnNiDR容器钢板组织及断裂性能的影响

利用光学显微镜、扫描电镜、热膨胀分析仪等对连铸-轧制方式生产的60 mm厚09MnNiDR容器钢板经不同亚温淬火+回火工艺处理后的组织和低温冲击性能进行了分析。结果表明:相比两次亚温淬火+回火工艺,采用淬火+亚温淬火+回火工艺的试验钢1/2厚度处冲击吸收能量大大提高,这与组织中小尺寸晶粒的占比提高有关;前者冲击断口形貌表现为准解理断裂,后者则为韧性断裂。     

390 MPa级复合钢板极地低温环境适应性分析

目的 验证复合钢板的极地低温环境适应性。方法 采用爆炸复合的方法制备低温复合钢板。通过全浸腐蚀试验、间浸腐蚀试验、腐蚀磨损试验、系列温度冲击试验、系列温度动态撕裂试验和全厚度止裂试验,分别评价复合钢板的耐蚀性、耐磨性能、低温断裂性能及止裂性能,并对复合钢板的低温断裂性能及极地低温环境适应性进行分析。结果 全浸腐蚀条件下,复合钢板基层材料的腐蚀速率是复层材料的105倍;间浸腐蚀条件下,复合钢板基层材料的腐蚀速率是复层材料的350倍;全浸和间浸状态下,复层钢板的腐蚀速率均远小于基层钢板,复层材料的耐蚀性远远好于基层材料。模拟海水条件下,复合钢板复层317L不锈钢的磨损量为0.003,基层FH40钢的磨损量为0.75,基层材料的磨损量是复层的250倍,复层材料的耐磨性远远好于基层材料。分析了20组大厚度规格低温钢的韧脆转变特征温度与止裂温度的相关性关系,指出了现有规范与标准以冲击功作为低温钢断裂性能技术指标的局限性,建立了止裂温度与动态撕裂韧脆转变特征温度相关性方程,给出了低温钢极地环境低温服役下的韧脆转变特征温度建议值,确定了复合钢板极地低温环境服役的最低温度。结论 模拟海水环境下,复合钢...     

架桥机大臂钢板开裂分析

架桥机大臂钢板在使用过程中发现表面呈方形开裂,但远未达到设计使用寿命。钢板材料为低合金结构钢Q345,其综合力学性能良好。为了弄清钢板开裂原因,通过宏观观察、扫描电镜及能谱仪分析、光学显微分析等对开裂钢板进行了深入探讨,结果表明:钢板失效属于疲劳断裂,疲劳起源于焊缝夹渣,并沿着方形焊缝路径扩展。焊缝中亦存在马氏体组织,马氏体组织较脆,裂纹遇到这种组织也较容易扩展。因此,在循环使用应力作用下,起源于焊渣的疲劳裂纹沿焊缝不断扩展,最终导致钢板呈方形断裂失效。可通过改善焊接工艺、增加焊接线能量以及焊前预热处理等途径来防止裂纹产生。     

电化学充氢对Cr15铁素体不锈钢和304奥氏体不锈钢氢脆敏感性的影响

研究了充氢时间、充氢电流密度、晶体结构对不锈钢氢脆敏感性的影响。结果表明:对于铁素体不锈钢,随着充氢时间的延长、电流密度的增大,塑性显著降低,氢脆敏感性大幅度增加;通过SEM观察实验钢断口形貌,断裂类型由韧性断裂转变为脆性断裂。而相同条件下,奥氏体不锈钢氢脆敏感性较低,抗氢脆性能较好。充氢后实验钢表面存在大量H,且氢含量随试样深度逐渐降低,晶界可能作为氢陷阱影响实验钢的氢脆敏感性。     

Welding characteristics of heavy-gauge plates for nuclear vessels

Abstract

The results are given of the characterisation of a weld made on a plate of A533B C1 1 steel, used in the construction of BWR nuclear vessels.

The work was carried out under an ENEL-CRTN research programme conducted at the CISE for the study of the structural integrity problems of the primary circuit components of BWR nuclear plants, and focused in particular on the application of fracture mechanics techniques.

The weld was made transversely by automatic submerged-arc welding on a 136mm thickness plate.

The parent metal, the weld and the HAZ were characterised from both the microstructural and the mechanical points of view; in particular, the fracture toughness properties up to 300°C were determined, under both static and dynamic conditions.

The fatigue crack propagation was also studied in an environment simulating the plant operating conditions.     

化学成分对316L奥氏体不锈钢组织及变形行为的影响

利用万能试验机对不同镍当量(Nieq)的316L不锈钢热轧钢板进行常温单轴拉伸试验,借助扫描电镜(SEM)和透射电镜(TEM)对其拉伸变形前后的微观组织进行观察,探索镍当量对316L不锈钢微观组织及性能的影响规律。结果表明,固溶态试验钢的组织均为奥氏体组织及少量高温δ相,强度随Nieq的升高而降低,塑性和韧性随Nieq升高而增加;拉伸断口均呈韧性断裂特征,且随Nieq的提高,韧窝的数量减少,韧窝尺寸增加;TEM显示,变形后的试验钢均未发生马氏体相变,Nieq较低时,变形量大的地方位错密度高,发生位错交互作用,局部有形变孪晶生成,且随着Nieq的增加,形变孪晶密度增大,出现相互交叉、阻滞。     

W6Mo5Cr4V2钢内裂纹愈合过程中碳化物的生长现象

采用物理模拟的方法研究了W6Mo5Cr4V2钢裂纹愈合区的组织特点。通过扫描电镜观察发现,在真空加热条件下高速钢裂纹的愈合过程与碳化物的生长有密切关系。碳化物在裂纹区的生长和聚集所产生的“桥接”作用实现了裂纹面之间的冶金结合。分析了碳化物在裂纹区的生长过程。     

新型1500MPa级高强钢的氢脆敏感性研究

根据钢材组织设计的思想，通过优化成分和工艺设计、研制出一种新的1500MPa级高强纲。采用阴极电解充氢的方法对其氢脆敏感性进行了研究，并与同一强度级别的42CrMo高强钢进行了对比。结果表明，所设计的1500MPa级高强钢的氢脆敏感性低于传统的42CrMo高强钢。SEM断口观察显示，两者的断口形貌也不同，1500MPa级高强纲为准解理断裂，而42CrMo高强钢为沿晶断裂。断口金相表明，前者的裂纹主要沿着贝氏体/马氏体（B/M）边界扩展，断裂模式为板条界分离，后者的裂纹沿着晶界扩展。对1500MPa级高强钢进行了TEM观察，发现其组织为贝氏体/马氏体复相组织，残留奥氏体以薄膜状存在贝氏体内部及贝氏体条片、马氏体板条间。     

ON THE FRACTURE DELAMINATION OF HOT-ROLLED PLATES OR COILS

本文研究了热轧板(卷)断口分层形成的冶金因素。钢中存在与轧面平行的脆弱显微平面(延伸的夹杂物和树枝状偏析等)是产生分层的内在因素,当它们在断裂面下严重偏聚时,在断裂过程中厚向应力的作用下引起厚向分离,形成断口分层。沿晶脆化带的形成是由于卷曲后缓慢冷却过程中,磷等杂质元素从晶内向晶界扩散产生的回火脆性。低温轧制(低于A_(r3))产生平行板面的(100)织构时,分层裂纹以解理方式扩展。 形成分层的必要条件是金属基体具有足够高的韧性,使试样在断裂过程中发生塑性变形。控制能量冲击试验结果和分层壁上脆性平面存在波纹状滑移线,说明分层裂缝产生于主断口断裂之前。