共查询到19条相似文献,搜索用时 140 毫秒
1.
2.
为了克服水下湿法焊条仰焊位置难以施焊的困难,文中提出了一种水下焊条半干式仰焊新工艺,并阐明了该工艺的基本原理和操作方法,且对其焊接工艺性能、焊缝组织、硬度以及扩散氢含量进行了分析. 结果表明,所提出的半干式仰焊工艺可以实现水下焊条仰焊位置焊接,焊缝成形良好,对于直径3.2 mm的水下焊条最佳焊接电流范围为100~140 A,焊接电压为28~32 V;该方法焊缝微观组织主要为侧板条铁素体、针状铁素体和贝氏体,与传统水下湿法焊条焊相比,铁素体的含量增加而贝氏体含量减少;焊接接头最高硬度值和熔敷金属扩散氢含量也明显低于水下湿法焊条焊. 相似文献
3.
4.
5.
6.
7.
8.
9.
焊接电参数(电弧电压、焊接电流)包含着丰富的焊接过程信息.针对水下湿法焊条电弧焊工艺,在不同焊接工艺条件(不同水深、不同焊条)时在线采集焊接电弧电压瞬时值,然后对其进行统计处理.利用电弧电压标准差σU以及电弧电压瞬时值与电弧电压平均值差值H的频率对比和焊接过程稳定性指数W相结合的方式,对水下湿法焊条电弧焊接过程的稳定性进行直观分析和定量评价.结果表明,利用W可以很好地识别不同焊接过程的稳定性,为水下焊接工艺稳定控制提供了新的方法,具有重要的理论意义. 相似文献
10.
带水施焊和切割,一般说来是比较困难的。特别是压力水管(容器)的带水施焊和切割,通常是使用专用水下焊条和设备来完成的。由于专用水下焊条和割条缺乏,实际生产中又经常遇到压力水管(容器)局部损伤、锈蚀,需要抢修,以及在保证正常供水情况下安装新管道或设备。为此,需要采用 相似文献
11.
This work investigates microbially-influenced corrosion (MIC) of stainless steel AISI 316 by two sulphate-reducing bacteria, Desulfovibrio desulfuricans and a local marine isolate. The biofilm and pit morphology that developed with time were analyzed using atomic force microscopy (AFM). Electrochemical impedance spectroscopy (EIS) results were interpreted with an equivalent circuit to model the physicoelectric characteristics of the electrode/biofilm/solution interface. D. desulfuricans formed one biofilm layer on the metal surface, while the marine isolate formed two layers: a biofilm layer and a ferrous sulfide deposit layer. AFM images corroborated results from the EIS modeling which showed biofilm attachment and subsequent detachment over time. 相似文献
12.
在不锈钢基体上分别镀上几种镀层,各自与船用铝合金配对测腐蚀速率,并测定了镀层在海盐溶液(3.5%)中的电极电位与极化曲线.结果表明,镀Zn-Ni的18-8钢自身腐蚀不大,还可使船体材料的腐蚀速率最小.
相似文献
13.
X.T. Chang Y.S. Yin G.H. Niu T. Liu S. Cheng S.B. Sun 《金属学报(英文版)》2007,20(5):334-340
The corrosion behavior of carbon steel in the medium of marine microorganisms was investigated by electrochemical impedance spectra, polarization curves, and so on. Experimental results showed that the corrosion potential of carbon steel moved in a negative direction in the unpurified marine microorganism solution, and the polarization style of the cathodic process did not change. The electrochemical impedance spectra showed that the impedance value of the electrode decreased in the medium with bacteria, which indicated that the existence of microorganism could accelerate the corrosion progress of carbon steel. 相似文献
14.
开发了一种新型全位置立向下焊条,采用有约束的配方均匀设计,对焊条配方进行了优化,采用GX-Ⅲ高温物性测试仪对焊条药皮的熔化特性进行了研究.结果表明,开发的全位置立向下焊条具有优良的工艺性能,焊缝成形美观,易脱渣,电弧稳定,飞溅率小等;该焊条具有较高的抗拉强度、屈服强度和较高的低温冲击韧性,能广泛应用于重要结构焊接.通过对焊接接头断口、金相组织以及焊缝成分和焊接接头横截面硬度分析表明了焊缝具有较高力学性能.形成了一整套开发全位置立向下焊条的新方法,该方法具有开发周期短、成本低、质量高的特点. 相似文献
15.
The performance of three time of wetness (TOW) determination methods during outdoor exposure was examined. Two impedance-based TOW sensor types, RH, and temperature sensors were exposed to coastal marine and laboratory environments for up to three months. The sensor and ISO 9223 methods examined provided incomparable estimates. Inaccuracy of the ISO method originated from a humidity threshold well above the drying point of deposited aerosols and differences between surface and ambient RH. TOW sensor accuracy was linked to electrode configuration. Small electrode spacing was demonstrated to be required to capture the range of wetting events of importance to atmospheric corrosion. 相似文献
16.
17.
J.A. Wharton R.C. Barik G. Kear R.J.K. Wood K.R. Stokes F.C. Walsh 《Corrosion Science》2005,47(12):3336-3367
Nickel–aluminium bronze (NAB) alloys show good corrosion resistance under marine conditions. The corrosion behaviour of cast and wrought NAB alloys is illustrated in this work through a range of electrochemical techniques including open-circuit potentiometry with time, oxygen reduction voltammetry, NAB dissolution voltammetry, potential step (or flow step) current transients and linear polarisation resistance. The galvanic coupling of NAB to stainless steel or copper is examined by zero resistance ammetery. The importance of using controlled flow working electrodes is illustrated by the use of a rotating disc electrode, a rotating cylinder electrode and a bimetallic (NAB/copper–nickel) rotating cylinder electrode. In addition to controlling the hydrodynamics, such electrodes allow charge transfer data to separate from those of mass transport control under mixed kinetic control. Longer term seawater immersion trials on planar coupons coupled to titanium or cupronickel are also reported. The relative contributions of erosion and corrosion attack are considered using a wall-jet electrode and the corrosion characteristics of NAB are compared to those of copper and copper–nickel in chloride media. 相似文献
18.
19.
开发了一种耦合电弧钨极,可显著降低电弧压力,消除咬边和驼峰焊道等缺陷,实现较高速度的TIG焊接.针对这种钨极进行了TIG电弧压力测量,研究了主要工艺参数对电弧压力分布的影响规律.结果表明,与传统TIG电弧相比,在相同参数下耦合电弧钨极TIG电弧压力峰值明显降低,并且随着弧长的增加、钨极伸出长度的增加、焊接电流的减小、电极槽宽的增大以及钨极直径的增大,耦合电弧钨极TIG焊的电弧压力峰值减小.对电弧压力的影响由大到小依次为焊接电流、钨极伸出长度、弧长和钨极直径、电极槽宽. 相似文献