Table 1 - Welding Conditions

In general, cooling speed decreases in use of a thinner base metal or a higher interpass temperature when the heat input is kept constant. Therefore, in order to attain targeted weld quality, heat input and interpass temperature should properly be controlled according to the thickness of the base metal. in use and required qualities of the weld.

LB-62L Maintains Adequate Tensile Strength Over Extended PWHT

Some weld joints where residual stresses are prone to concentrate (e.g. a crown plate to nozzle weld joint of a spherical tank) require postweld heat treatment (PWHT). As usual with ferritic weld metal, the strength of LB-62L weld metal decreases as PWHT temperature and soaking time increase. However, LB-62L weld metal maintains adequate tensile strength over the minimum tensile strength (550N/mm2) of A537 Cl-2 steel even after extended PWHT as shown in Fig. 4. In addition, some types of weld metal lose notch toughness due to embrittlement caused by PWHT. LB-62L weld metal, however, maintains adequate notch toughness even after PWHT as shown in Fig. 5.

Fig. 4 - Strength of LB-62L all-deposited metal vs. PWHT parameter (Power source: DC-EP, Heat input: av. 19kJ/cm, Welding position: flat)

Fig. 5 - The effect of postweld beat treatment on impact absorbed energy of LB-62L (4.0(j)) weld metal (Power source: DC-EP, Heat input: av. 38.7kJ/cm, Welding position: Vertical up. Base metal: A537 Cl-2, Groove preparation: double V)

LB-62L Offers Extra-Low Hydrogen and Moisture Resistant Characteristics

LB-62L offers extra-low hydrogen weld metal, which decreases the preheating temperature needed for preventing cold cracking. In addition, LB-62L picks up less moisture due to its moisture resistant coating compared with conventional low-hydrogen electrodes — Fig. 6. Such outstanding features can make quality control easier and more economical by reducing the costs for preheating the work and redrying the electrode. 2.0

Fig. 6 - Test results of LB-62L and a conventional low- hydrogen electrode on moisture pick-up under the controlled atmosphere: 3(fC X 80%RH.