Application of Solid Core Welding Wire in High Strength Steel Welding of Offshore Engineering

1 Overview

Our products mainly include jackets, offshore cranes, tanker modules, tanker mooring systems, drilling vessels and LNG projects. The traditional bottoming bead is welded by SMAW. In order to ensure the quality of the welding, a large amount of grinding is required before filling and welding. On the one hand, the working environment is deteriorated, and on the other hand, the working efficiency is lowered. Therefore, a relatively efficient hitting is considered. Bottom mode - STT base. GTAW manual welding limits the welding efficiency, so the introduction of automatic GTAW.

2. Solid wire welding base application

(1) Application on ultra-high-strength steel The offshore crane project has adopted a large number of ultra-high-strength steel of Q690 strength grade. In the project structure, there is a joint of 15CrNiMoV forged steel and ultra-high-strength steel Tenaris S690. S690 steel belongs to low-alloy high-strength steel. Such welded joints are prone to defects such as hardening, embrittlement and cracking. The welding is difficult and the joint form is special. It is impossible to clear the roots (see Figure 1). For this reason, we adopted Lincoln STT. Technology (surface tension transition) primer welding to achieve single-sided welding double-sided forming. The welding material is selected from the German Klein company union K52Ni solid core welding wire. During the welding process, the welding parameters of the ultra-high strength steel and the dissimilar high-strength steel are achieved through strict control of the welding parameters, and the welded joints have excellent mechanical properties.

figure 1

(2) Use of marine steel plates The E36 and D36 marine steel plates are widely used in the jacket project. During the construction of the project, a large number of pipes with a diameter of <600m need double-sided welding. Due to the low efficiency of traditional electrode arc welding, the company uses solid wire to improve the efficiency. JM of Jintai Company is selected. 58 bottoming, with the Lincoln STT welder, successfully completed the welding task. In addition, the solid core welding wire is also applied in the welding of Fangtong.

(3) Solid wire for pipeline steel For pipeline welding, argon arc welding or electrode arc welding is traditionally used, and the welding efficiency is low. For this reason, we actively test and select the welding material with the same strength as steel for welding the pipeline. For carbon steel, we chose GTL-53 from Jingqun Co., Ltd., and the stainless steel welding wire used T-308L from Korea, which achieved good results in the test.

3. Expectations and recommendations

In the construction of marine steel structures, there are many processes that require single-sided welding and double-sided forming (see Figure 2). For special groove forms, such as some single bevel forms, GMAW has its limitations and is prone to unfused. The welding joints with good fusion properties can be obtained by optimizing the welding parameters or adjusting the characteristics of the welding arc, which has positive significance for the wide application of GMAW.

figure 2

About the author: Jia Xiaoyan, Wang Shida, Penglai Jutao Ocean Engineering Heavy Industry Co., Ltd.

Related product links:

(1) Bohler union K52 Ni: 1Ni alloy low temperature steel welding wire: excellent welding performance, suitable for all-position welding; its weld metal has good impact resistance at -60 ° C; high weld purity, extremely low trace harmful elements Suitable for welding low temperature steel such as 1Ni or SA 203Gr. D; suitable for welding low temperature pressure vessels, storage tanks and pipes.

(2) Jingqun GTL-53 is a 490MPa grade argon arc welding wire used for welding of low carbon steel and low alloy steel. The arc is stable during welding, the appearance is beautiful, the fluidity of molten iron is good, the crack resistance is excellent, the content of deposited metal P and S is extremely low, and it has excellent plasticity and impact toughness (-46°C up to 265J), anti-HIC and SSC performance. Excellent.