LB-52NSU日本神鋼焊條 低合金低溫鋼高強(qiáng)鋼焊條進(jìn)口焊條進(jìn)口焊絲

西安駿焊銷(xiāo)售日本神鋼焊條焊絲

4.1.  LB-52NSU

When pipe root pass welding must be conducted from outside rather than inside in order to form the back bead inside the pipe, GTAW or SMAW are generally favored. Kobe Steel has long marketed FAMILIARC? LB-52U as well as FAMILIARC? LB-62U for this purpose, and they still serve as Kobe’s most reliable, “one and only” products worldwide.

In addition to meeting the always-changing and diverse specifications of pipelines, TRUSTARC? LB-52NSU has been developed specifically for root pass welding of pipes for low temperature service. It is a covered, low hydrogen type electrode equivalent to AWS A5.5 E7016-G. It offers superb notch toughness at -60°C and very low diffusible hydrogen content of about 3.0ml/100g. The chemistries, mechanical properties of all weld metal and diffusible hydrogen content of TRUSTARC? LB-52NSU are shown in Tables 3, 4 and 5 respectively.

Table 1: Covered electrodes for girth welding

Table 2: TIG and MAG wires for girth welding

Table 3: Chemistries of TRUSTARCTM LB-52NSU all weld metal (mass %)

Table 4: Mechanical properties of TRUSTARCTM LB-52NSU all weld metal

Table 5: Diffusible hydrogen content of TRUSTARCTM LB-52NSU (ml/100g)

Note: Tested method: According to AWS A4.3.(Gas chromatography)
            Welding current: 120 A (DCEP)
            Welding atmosphere: 21°C x RH10%

Figure 3: Groove shape and pass sequence of butt joint
welding with TRUSTARCTM LB-52NSU(root pass only)
and TRUSTARCTM LB-52NS

In welding a butt joint on a 25 mm thick plate, 3.2 mm dia. TRUSTARC? LB-52NSU was used for the root pass with DC 95 amp, and 3.2 mm dia. TRUSTARC? LB-52NS was used for the second pass onwards with DC 110 amp in the vertical upward . The preheating and interpass temperatures were kept between 115 and 135°C. Figure 3 shows the groove shape and the pass sequence and Figure 4, the macrostructure of the weld metal. The chemistries and the tensile properties are shown in Tables 6 and 7, respectively and the notch toughness properties and the transition curve of the butt joint weld metal are shown in Table 8 and Figure 5, respectively. (Note: both TRUSTARC? LB-52NSU and TRUSTARC? LB-52NS are specified as AWS A5.5 E7016-G).

Figure 4: Macrostructure of butt joint weld 
metal

Table 6: Chemistries of butt joint weld metal (mass %)

Table 7: Tensile properties of butt joint weld metal