不同Nb含量X80钢管环焊热影响区的微观组织与韧性

为研究Nb含量对焊接热影响区微观组织和性能的影响,采用熔化极气体保护焊(gas metal arc welding,GMAW)和手工焊条电弧焊(shielded metal arc welding,SMAW)对0.055%Nb和0.075%Nb含量的X80钢管进行环焊.采用夏比冲击试验和金相分析方法,研究热影响区的微观组织差异和夏比冲击韧性.并借助扫描电镜和超高温激光共聚焦显微镜分析不同Nb含量X80管体的微观组织对热影响区性能的影响.结果表明,在0℃和-20℃时,0.075%Nb和0.055%Nb的X80钢管GMAW环焊接头热影响区均具有较高的冲击韧性,其平均冲击吸收能量均高于150 J.其中0.055%Nb略高于0.075%Nb的GMAW环焊接头热影响区夏比冲击吸收能量;焊接热输入较低时,0.055%Nb低于0.075%Nb的X80环焊接头粗晶区的韧脆转变温度,具有更好的低温韧性.焊接热输入较高时,0.075%Nb的X80环焊接头粗晶区具有更高的上平台冲击吸收能量,且上平台温度和韧脆转变温度也更低,其低温韧性也更优异;还发现了X80环焊接头热影响区的冲击韧性不仅与热输入量和热影响区马氏体-奥氏体组织(M-A)的形状、大小、分布有关,而且还受管体中Nb含量、原始的强度与韧性、微观组织状态的遗传影响.

高铌X80管道不同强度匹配环焊接头性能及应变演化

为探究管道环焊缝断裂失效机理,测试了两种不同强度匹配的高铌X80环焊缝接头的组织和性能,并借助数字图像相关法(digital image correlation, DIC)观测了焊接接头在拉伸载荷下的应变行为.结果表明,低强匹配和高强匹配的高铌X80管道环焊接头均具有较好的冲击韧性,二者的夏比冲击吸收能量平均值相当,热影响区韧性离散主要是粗晶区组织不均匀性所致;高铌X80管线钢碳当量CEIIW较低,环焊缝接头热影响区存在一定程度软化.在轴向拉伸载荷下,无论是低强匹配还是高强匹配,应变集中最先出现在环焊缝的根焊和热影响区部位.随着拉伸载荷的增加,高强匹配环焊缝接头的应变集中逐渐从根焊和热影响区转移到母材,管道承受轴向载荷和变形的能力大于低强匹配环焊接头;而对于低强匹配,因在焊缝和热影响区产生塑性应变累积,即使具有较好的韧性,环焊接头也会发生断裂.

几种典型X80管线钢管及其环焊缝性能研究

环焊缝质量是影响高钢级长输管道安全的重要因素之一。国际焊接研究中心(IWTC)针对几种典型X80管线钢的焊接开展了大量研究,测试了钢管管体和环焊缝的组织及关键力学性能,分析了X80管线钢管环焊工艺及环焊缝性能影响因素,给出了推荐工艺参数、控制措施等。采用焊接热模拟试验研究了2种不同Nb含量的X80钢管的焊接性,分析了Nb含量对焊缝区域微观组织的影响机制。结果表明,国内典型的X80管线钢管均具有良好的性能,其管体性能及焊接性满足工程需要;应采用合理的环焊工艺和质量控制措施以保证焊缝的性能;铌含量较高的X80管线钢具有更优越的焊接性,但必须严格遵从焊接工艺规范。

强度匹配对X80螺旋埋弧焊管环焊接头宽板拉伸性能的影响

为了研究不同强度匹配下X80螺旋埋弧焊管环焊接头的拉伸性能,采用等强匹配根焊+高强匹配填充盖面焊和低强匹配根焊+等强匹配填充盖面焊的两种不同强度匹配组合进行了熔化极气体保护自动焊(GMAW),测试了环焊接头的拉伸性能和夏比冲击韧性,并采用宽板拉伸试验研究了环焊接头的拉伸性能和失效行为。结果表明,两种强度匹配下的X80钢管GMAW环焊缝接头均具有较好的形变能力,二者的平均总应变均大于4.0%;最大载荷下,两种强度匹配组合的环焊接头全截面抗拉强度略低于环焊接头小尺寸试样的抗拉强度,但等强+高强匹配的环焊接头具有更高的平均总应变、平均远端应变和裂纹口张开量,失效模式为管体母材发生颈缩失效,而低强+等强匹配组合的GMAW环焊接头失效模式为根焊热影响区发生开裂失效。试验表明,对于X80螺旋埋弧焊管环焊接头,可选用具有一定韧性的等强度焊接材料进行根焊,从而避免焊缝根部产生应变集中而失效。

The Critical Rainfall Characteristics for Torrents and Debris Flows in the Wenchuan Earthquake Stricken Area

Critical rainfall assessment is a very important tool for hazard management of torrents and debris flows in mountainous areas. The Wenchuan Earthquake 2008 caused huge casualties and property damages in the earthquake-stricken area,which also generated large quantities of loose solid materials and increased occurrence probabilities of debris flows. There is an urgent need to quantify the critical rainfall distribution in the area so that better hazard management could be planned and if real time rainfall forecast is available,torrent and debris flow early-warning could be issued in advance. This study is based on 49-year observations (1954-2003) of up to 678 torrent and debris flow events. Detailed contour maps of 1 hour and 24 hour critical rainfalls have been generated (Due to the data limitation,there was insufficient 10 minute critical rainfall to make its contour map). Generally,the contour maps from 1 hour and 24 hours have similar patterns. Three zones with low,medium and high critical rainfalls have been identified. The characteristics of the critical rainfall zones are linked with the local vegetation cover and land forms. Further studies and observations are needed to validate the finding and improve the contour maps.

纳米技术、微型机械和延年益寿

介绍了21世纪世界科技发展的一个重要方向——电子技术、计算机和机械走向纳米级的微型化,同时具有超越的功能。它不但会影响机械,而且将影响医药、环境、健康以致延长人的寿命。

Iatrogenic opioid dependence is endemic and legal: Genetic addiction risk score (GARS) with electrotherapy a paradigm shift in pain treatment programs

The mounting endemic of prescription iatrogenic opioid dependence in pain patients provoked this treatise about an alternative method that can be used to treat pain, improve function and reduce the risk of opioid dependence. It is well known that as well as the side effects reported for chronic opioid therapy, genetically predisposed individuals are at risk for opioid dependence. We propose the use of the Genetic Addiction Risk Score (GARS) assessment to identify patients early in treatment who should avoid narcotic pain medications. Primarily, this review will be an exploration of the mechanisms of action of an electrotherapeutic alternative to narcotic treatment that can be used to augment tissue healing and reduce the pain associated with human injuries and neuropathies. This particular electrotherapeutic device was developed at the Electronic Waveform Laboratory in Huntington Beach, California and is called the H-Wave? device. The primary effect of the H-Wave?device is stimulation (HWDS) of small diameter fibers of “red-slow-twitch” skeletal muscle. Mechanisms of action of HWDS have been investigated in both animal and human studies. They include edema reduction, induction of nitric oxide dependent augmented microcirculation and angiogenesis, small muscle contraction that eliminates transcapillary fluid shifts, reducing the painful effects of tetanizing fatigue and gradual loading of healing injured muscle tissue that helps repair and remodeling. A recent metaanalysis found a moderate-to-strong-positive effect of the HWDS in providing pain relief, reducing the requirement for pain medication, with the most robust effect being increased functionality. We are proposing that GARS can be used to identify those at risk of developing opioid dependence and that the need for opioid analgesia can be reduced by use of this electro therapeutic alternative to opioid analgesia in the treatment of pain and injuries.

不同强度匹配的X80钢环焊接头力学性能及变形能力

环焊接头的强度匹配与韧性对管道服役安全至关重要。为了更深入掌握环焊缝的失效机理,采用力学性能测试、微观分析等方法,测试了两种不同强度匹配的高铌X80钢环焊接头的组织和性能,并借助数字图像相关法(Digital Image Correlation,DIC)研究了焊接接头在拉伸载荷下的应变行为。结果表明:低强匹配与高强匹配的环焊接头均具有较好的冲击韧性,二者的夏比冲击吸收能量平均值相当。在拉伸载荷下,应变集中最先出现在环焊缝的根焊及热影响区部位。随着拉伸载荷的增加,高强匹配环焊接头的应变集中逐渐转移至母材,管道承受轴向载荷及变形的能力大于低强匹配环焊接头;低强匹配环焊接头虽具有较好的韧性,但因其在焊缝及热影响区存在塑性应变累积效应,易发生断裂。(图9,表4,参22)