激光焊接牙科铸造纯钛研究

研究了激光焊接技术对牙科铸造纯钛的机械性能和耐腐蚀性能的影响.用扫描电境观察焊缝区形貌并测试了焊件的抗拉强度.结果表明激光焊接对铸钛的机械性能及耐应力腐蚀性能无明显影响.     

工业纯钛的焊接

结合衬钛设备的结构,着重对工业纯钛氩弧焊的保护效果,焊接规范参数的选取进行了试验分析,并对焊缝的气孔,焊缝的金相组织和焊缝的污染程度对质量的影响进行了一般性的讨论。     

纯钛带坯焊接轧制工艺研究

钛材由于其高的比强度和优良的耐蚀性而广泛的医用于石油化工、航空航天、兵器、电子、医疗等行业．随着我国化工行业的进展,其生产连续化,对所用的钛带材需求量增大,且要求钛带材越长越好．我厂生产的钛带主要用于化工行业,为适应市场的需求,针对目前国内无大卷钛带坯,国外钛带卷价格较高,放采用片式钛带坯经焊接轧制工艺生产,并对其进行了有关性能测试,结果表明性能无大差异,此工艺可行．1实验步骤1．1备料本实验采用化学成分符合GB3620．1－94的纯钛带坯,牌号为TA1,规格为：1．0mm×310mm×2500mrn以上,0．5mm×310mm×20…     

纯钛工业管道TIG焊接实践

通过对纯钛进行可焊性分析,发现其焊接的主要缺陷是接头污染、接头变脆和气孔,明确了焊接过程的控制关键是焊接过程的保护、焊前清理以及控制线能量,针对以上控制要点了进行了细致的阐述,提出了全过程、全方位、动态的全面保护理念,并且通过对不同的焊接工艺进行试验,找出避免钛氧化污染的最佳参数,从而针对马钢合肥公司炼铁厂焦化车间煤气净化系统改造项目的纯钛工业管道制定了合理的工艺,实践证明,该工艺收到了良好的效果。     

钛焊接接头的残余应力

纯钛在海洋环境中具有优良的耐蚀性和耐生物附着性。用于凝汽器的海水冷却管在船舶上使用涉及到纯钛焊接板骨架构件的船舶结构材料时，其焊接残余应力对疲劳强度、压曲强度的评价很重要。即在疲劳行为上，拉伸的残余应力呈现出使平均应力增大的相同效果，从而使测得的疲劳强度偏低。对角焊焊接的板骨结构，焊接部位存在着残余应力，与之平衡在所围骨架的板中央附近产生了压缩残余应力，这种残余应力使压曲负载下降。但对纯钛的焊接接头残余应力缺乏研究，因此，日本学者为了评价纯钛焊接构件的疲劳、压曲强度，对纯钛的焊接接头残余应力进行…     

激光表面重熔对工业纯钛板腐蚀行为的影响

钛在湿氧环境中，其表面会形成一层致密稳定的氧化薄膜，具有优异的抗蚀性；但在缺氧无水环境中，钛会出现点蚀现象。为了扩大钛使用范围，延长其在恶劣环境中的使用寿命，诸如激光表面重熔等表面处理技术已被广泛用于钛的表面处理。新加坡学者探讨了激光表面重熔技术对纯钛板的抗腐蚀性和点蚀电位的影响。     

基于全场应变的工业纯钛激光焊接头组织与拉伸性能

研究了激光焊热输入对3 mm TA2纯钛薄板焊接性能的影响,采用数字图像相关(Digital Image Correlation, DIC)图像处理技术对焊缝拉伸进行实时全场应变监测,分析焊缝应力应变,结合显微金相、背散射电子衍射(EBSD)、硬度,得到焊缝性能增强原因。结果表明：激光焊接TA2薄板能获得良好的成形性能及拉伸性能,焊缝抗拉强度始终优于母材的;在拉伸塑性阶段焊缝的应变明显低于母材的,出现了强度提高塑性降低的现象;焊缝显微组织为针状α晶、锯齿状α晶和粗大等轴α晶,热影响区显微组织为粗大等轴α晶及针状α晶,针状α晶由热影响区外侧到内侧生成量逐渐增多,直至遍布焊缝区域;焊接接头硬度由焊缝向母材呈递减趋势。     

工业纯钛电镀槽焊接工艺设计

根据工业纯钛的焊接特性,通过焊接工艺评定试验,设计了电镀槽的氩弧焊焊接工艺,分析了影响焊缝质量的主要原因,提出了提高焊缝质量的工艺措施.     

牙科铸钛技术的研究现状

对目前牙科铸钛系统,包埋材料、铸件表面反应层结构以及铸造工艺如铸模温度、铸造压力等的研究及发展现状进行了综合介绍。     

Tensile Properties and Work Hardening Behavior of Laser-Welded Dual-Phase Steel Joints

The aim of this investigation was to evaluate the microstructural change after laser welding and its effect on the tensile properties and strain hardening behavior of DP600 and DP980 dual-phase steels. Laser welding led to the formation of martensite and significant hardness rise in the fusion zone because of the fast cooling, but the presence of a soft zone in the heat-affected zone was caused by partial vanishing and tempering of the pre-existing martensite. The extent of softening was much larger in the DP980-welded joints than in the DP600-welded joints. Despite the reduction in ductility, the ultimate tensile strength (UTS) remained almost unchanged, and the yield strength (YS) indeed increased stemming from the appearance of yield point phenomena after welding in the DP600 steel. The DP980-welded joints showed lower YS and UTS than the base metal owing to the appearance of severe soft zone. The YS, UTS, and strain hardening exponent increased slightly with increasing strain rate. While the base metals had multi-stage strain hardening, the welded joints showed only stage III hardening. All the welded joints failed in the soft zone, and the fracture surfaces exhibited characteristic dimple fracture.     

Special Features of the Structure of Laser-Welded Joints of Dissimilar Alloys Based on Titanium and Aluminum

Metal Science and Heat Treatment - The structure of laser-welded joints of parts having different thicknesses fabricated from alloys based on aluminum and titanium has been studied. Results of...     

Cracking of Welded Joints of Cast and Deformed Titanium Alloy VT5

The macro- and microstructure and microhardness of welded joints of titanium alloy VT5 are investigated. Fracture surfaces are studied and fractional analysis of hydrogen in cast metals is performed. Suggestions are put forward as to the causes and mechanisms of formation of cracks in a weld joint of a forging and a casting from alloy VT5. Places of crack initiation and subcritical growth are determined.     

Mechanical and Functional Properties of Nickel Titanium Adhesively Bonded Joints

In this study, adhesive joints made up of commercial NiTi sheets with shape memory capabilities are analyzed. Suitable surface pre-treatments, i.e., degreasing, sandblasting, and chemical etching, are preliminary compared in terms of surface roughness, surface energy, and substrate thinning. Results indicate that chemical etching induces marked substrate thinning without substantial gains in terms of surface roughness and free energy. Therefore, adhesive joints with degreased and sandblasted substrates are prepared and tested under both static and cyclic conditions, and damage development within the adhesive layer is monitored in situ using a CCD camera. Sandblasted specimens have a significantly higher mechanical static strength with respect to degreased ones, although they essentially fail in similar fashion, i.e., formation of microcracks followed by decohesion along the adhesive/substrate interface. In addition, the joints show a good functional response with almost complete shape memory recovery after thermo-mechanical cycling, i.e., a small accumulation of residual deformations occurs. The present results show that adhesive bonding is a viable joining technique for NiTi alloys.     

TA15钛合金焊接接头性能与断裂行为研究

对TA15钛合金氩弧焊和电子束焊焊接接头的性能与微观组织进行了分析研究,并结合断口观察,对其断裂行为进行了研究.结果表明,两种焊接接头强度均与母材相当,而塑性明显降低.焊接接头热影响区组织均呈现从粗大等轴组织到魏氏组织的过渡变化特征.疲劳断裂位置一般位于靠近熔合线的焊缝区域,主要原因是此区域存在组织突变和熔合线气孔.焊接气孔对接头疲劳性能影响较大.两种焊接接头疲劳断口特征存在明显区别.     

铸造钛合金管坯的旋压成形及性能研究

研究了某铸造钛合金管件的旋压成形工艺,探讨了该钛合金热旋压过程常见缺陷产生的原因,对旋压件组织和力学性能进行了分析.结果表明:该铸造钛合金在一定的旋压条件下具有较好的可旋性,旋压后铸态晶粒被压扁拉长,形成明显的纤维组织,减薄率超过72＆时,铸态组织基本消除.旋压后材料强度和塑性指标均有所提高.     

钛对灰铸铁力学性能的影响

在生产条件下，钛对灰铸铁力学性能的影响。结果显示：灰铸铁中含钛量w为0．08％－0．1％时，能细化晶粒，提高铸件强度和品质系数，略微增加硬度；含钛量w为0．2％－0．3％时，铸件硬度明显增加，并降低铸件的加工性能和品质系数。     

ZTA15铸造钛合金材料的性能与应用

研究了ZTA15铸造钛合金材料在不同状态下的微观组织及室温力学性能,并对热等静压和退火状态的常温性能进行了分析。经试验及某航空结构件实际应用结果表明,ZTA15钛合金铸件性能稳定,完全满足技术条件及使用要求。