History – KOBELCO WELDING

The start of domestic covered
electrode production
(1932-1945)

Until around 1930, most covered electrodes used in Japan were imported, though leading shipbuilders and machinery fabricators were able to produce them for their own uses. Similarly, Kobe Steel also produced its own covered electrodes in-house. Around 1932, Kobe Steel began to pursue full scale research and development of covered electrodes, acknowledging the importance of welding technology, and responding to the increased demand for domestically-produced covered electrodes.

In 1942, Kobe Steel developed a high quality ilmenite electrode comparable to or better than the imported electrode, and the new electrode was given the name B-17. Almost immediately, B-17 was adopted full swing for ships and other heavy-duty naval structures. The monthly production of the electrodes reached 540 metric tons in the high season, which accounted for the bulk of total domestic demand in wartime. B-17, which is now classified as AWS A5.1 E6019, continues to be produced with consistent quality and is supplied domestic and overseas markets.

Production and supply
for civilian demand in the postwar era
(1945-1959)

After World War II, Kobe Steel’s main electrode factory, the Hidaka Plant, restarted production of covered electrodes for civilian uses in 1946 and was first in Japan to acquire the certificate of Lloyd’s Resister of Shipping (UK) for B-17 in 1948. Hence, the credibility of the quality of Kobe Steel electrodes was heightened, and, as a result, most of the electrodes used for building ships for export as well as for domestic use carried the Kobe Steel brand. In 1949, production of a new ilmenite electrode, the B-10 (E6019), started, and this electrode then became very popular for general applications.

In response to the sharp postwar increase in demand for welding electrodes, Kobe Steel built a state-of-the-art mass production factory, the Yamate Plant, in Kobe City in 1951. The new plant allowed Kobe Steel to achieve a monthly electrode production capacity of 1500 metric tons. That year, two new types of electrodes were developed for the first time in Japan: a titania electrode, called RB-26 (E6013) for thin steel work and a low hydrogen electrode, LB-26 (E7016), for thick steel work (Figure 1).

Figure 1: RB-26 and LB-26 joined B-17 and B-10 for diversified applications in the early postwar era.

In 1952, the KSL Welding Department took on a more integrated framework by organizing the research and development section at the Yamate Plant. The scope of products was expanded with special covered electrodes for high tensile strength steel, low alloy steel, stainless steel, and hardfacing to respond to the diversified needs of the market. That year, in order to expand sales of welding electrodes particularly to small-scale domestic customers and users, a sales network for Kobe Steel welding consumables, the “Shin Yo Kai,” was set up (Figure 2). The sales network has been expanded and strengthened ever since to cover the entire Japanese market.

Figure 2: The “Shin Yo Kai” sales network was established in 1952 to promote sales in the Japanese domestic market.

In 1954, a low hydrogen electrode, LB-52 (E7016), for high tensile strength steel was developed. Low hydrogen electrodes have greatly contributed to the rapid development of heavy-duty welded structures and machinery made of high tensile strength steel in Japan. Since around 1955, Kobe Steel began paying attention to the hazards of the welding fumes emitted from low hydrogen electrodes and may have been the first in the world to begin medical research into the effects of fumes on the health of welders. This research contributed to development of “harmless-fume” and “lowfume” covered electrodes such as LBM-52 (E7016) and ZERODE-44 (E6013) in later years.

Expansion and advancement in
the era of the booming economy
(1960-1974)

As economic growth soared in Japan, so did demand for welding consumables; as a result, the annual production of Kobe Steel electrodes reached 44,300 metric tons, straining the maximum capacity of both the Hidaka and Yamate Plants. In order to increase production capacity, upgrade and expand technical research and development, and respond to rising demand for welding consumables in the Tokyo metropolitan district, Kobe Steel established the state-of-the-art Fujisawa Plant in Fujisawa City in 1961. In the next year, the flux-processing factory and the research and development section were transferred to the Fujisawa Plant from the Yamate Plant. In the meantime, in order to respond to the increasing demand for welding consumables in western Japan, the Ibaraki Plant in Ibaraki City was established with the most advanced facilities including those transferred from the Yamate Plant in 1961. In particular, the Ibaraki Plant was outfitted with equipment for production of solid wires, taking into account the trends towards greater automatization in the welding industry.

In 1963, the Shinkannsen Super-Express Line was under construction so as to make ready for the Tokyo Olympic Games of 1964. For joining the long rails in the field, thermit welding was a standard method at the time. However, in order to speed up welding in the field, arc welding was also considered. At the request of the Japan National Railroad, Kobe Steel executed research and developed the enclosed arc welding process that used a rail-fit welding jig, high tensile strength steel covered electrodes of LB-116 (E11016-G) and LB- 80EM, and special postweld heat treatment. This enclosed arc welding process succeeded at joining long rails on site (Figure 3).

Figure 3: The long rails of the Shinkansen Super-Express Line were successfully welded by the enclosed arc welding process developed by Kobe Steel.

In the early 1960s, the Japanese shipbuilding industry began to expand to meet increasing demand for new ships: from 1,500,000 GT (12% of the world total) in 1962, Japanese ship production increased yearly up to 17,000,000 GT (50% of the world total) in 1975. To cope with such strong demand from the shipbuilding industry, Kobe Steel promoted research and development of submerged arc welding consumables. Fused fluxes, such as G- 50 and G-80, were produced and supplied by Hanshinn Yosetsu Kizai Co., Ltd., a joint venture between Kobe Steel, Ltd. and Osaka Transformer Co., Ltd. (currently Daihen Corp.) under technical collaboration (1959-1969) with Union Carbide Corp. In order to improve high-current usability and notch toughness of fused fluxes, the bonded flux, PFH-45, was developed in 1961 and first applied in a 64,000 DWT tanker in 1963; since then, the use of this flux has widened in shipyards throughout Japan.

Starting around 1963, tankers began to be designed with longer hulls. For more efficient fabrication of long ship hull blocks, shipbuilders desired a welding procedure that dispensed with the need to weld both sides of the steel plates. In response, Kobe Steel developed two different one-sided submerged arc welding processes along with the required fluxes in 1964: the RF (resin flux) process for 25-mm or thinner plates and the FCB (flux copper backing) process for 40-mm or thinner plates (Figure 4). These processes were employed for 10 years by successive Japanese shipbuilders eventually reaching over 40 shipyards. In addition, starting in 1970, the FCB process spread among shipbuilders overseas in former Yugoslavia, Italy, Spain, USA, and Korea.

Figure 4: The FCB process achieved ultimate welding efficiency in one-sided submerged arc welding of hull plates.

In 1968, Kobe Steel invested, for its first overseas investment, in the establishment of Thai-Kobe Welding (TKW) in cooperation with Watana Intertrade Co., Ltd. and Kim Chong Hin Import Export Co., Ltd. to produce and supply RB-26 for the Thai market.

In 1968, Kobe Steel began production and supply of MG solid wires, such as MG-50 (ER70S-G), under sublicense from Matsushita Electric
Industrial Co. Ltd. After that, Kobe Steel was able to establish a framework for supplying solid wires to the semi-automatic welding markets such as rolling stock, autos, and industrial machinery. To satisfy increased demand for covered electrodes from shipbuilders in western Japan, the Saijo Plant was established in Hiroshima prefecture in 1970. This plant features superior productivity and decreased labor costs.

In 1974, a highly-efficient, potable electrogas arc welding process named SEGARC was developed. Utilizing specific flux-cored wires, DWS-43G (EG70T-2), DWS-1LG, and DWS-60G. it offered high deposition rates. Since then SEGARC has been used for vertical welding joints in ship hulls, bridges, storage tanks, and large diameter pipes (Figure 5).

Figure 5: The SEGARC electrogas arc welding process was used for ship hull vertical joints.

Highly efficient welding consumables in the era of production rationalisation
(1975-1986)

In order to recover after the first global energy crisis hit in 1973, every industry promoted production rationalization. As a result, in the welding industry, every fabricator began to increase their use of the highly-efficient and cost-effective CO₂ arc welding process to improve welding efficiency and thereby decrease production costs. To respond to these new circumstances, production of solid wires at the Ibaraki Plant was increased; in addition, Kobe Steel built the Fukuchiyama Plant in 1975, equipping it with cutting-edge production facilities for solid wires, and thereby realizing production cost savings and quality improvement. In 1976, Intan Pertiwi Industry (INTIWI) was established as a technical collaboration in Indonesia and began to produce and supply covered electrodes under the license from Kobe Steel in 1977. Since then INTIWI has been producing a wide range of covered electrodes, including those for mild steel, high tensile strength steel, stainless steel, cast iron, and hardfacing. The company’s production and sales have increased, achieving 50% market share due to a high reputation among users.

In response to the market demand for improving efficiency and usability in stainless steel welding, the DW series of stainless flux-cored wires, DW- 308L (E308LT0-1/-4), DW-316L (E316LT0-1/-4), DW-309L (E309LT0-1/-4), and DW-309MoL (E309LMoT0-1/-4), was developed in 1978 (Figure 6).

Figure 6: DW stainless flux-cored wires contributed to high efficiency in stainless steel welding.

1978 saw the development of PICOMAX, equipment for multiple-use automatic welding that offered compact size, light weight, and easy operation. With this equipment, automatic gas shielded arc welding could be conducted with solid wires or flux-cored wires in one semi-automatic welding machine. Since then this equipment has been used for various applications such as steel structures, pipes, and storage tanks (Figure 7).

Figure 7: PICOMAX has contributed to production rationalization with its multiple functions.

In 1979, Kobe Steel expanded its overseas production base by establishing Kobe Welding (Singapore), KWS (Figure 8), to cover not only the Singaporean domestic market but also markets in neighboring countries. KWS began with production of covered electrodes for mild steel and high tensile strength steel. In KWS, the ASEAN Marketing Dept. (AMD) was organized to provide market-oriented technical services in the South East Asian markets. The AMD personnel covered technical services not only in Singapore but also in Malaysia, Thailand, Indonesia, and Philippines.

Figure 8: The position of KWS has been strengthened by increasing the production and sales of welding consumables.

1980 saw the development of DW-100 (E71T-1C), a rutile flux-cored wire for mild steel and 490MPa high tensile strength steel (Figure 9). This fluxcored wire was highly reputed for solid ultimate performance and provided the momentum for shipbuilders to employ automatic and semi-automatic welding with DW-100 instead of shielded metal arc welding with covered electrodes. Consequently, the consumption of DW-100 began to climb rapidly year after year. In 1981, Ni-bearing rutile flux-cored wires, DW-55E (E71T-9C-J) and DW-55L (E81T1-K2C), were developed for low temperature applications such as offshore structures in response to demand from the shipbuilding industry.

Figure 9: DW-100 was an epoch-making flux-cored wire that provided a core technology for developing other flux-cored wires.

In 1982, LB-52U (E7016), which had been developed in 1959 for “uranami” or root-pass meltthrough welding with penetration beads, was evaluated highly in a welding test of natural gas pipelines in the then Soviet Union (Figure 10). Kobe Steel successfully received a series of large purchase orders for LB-52U together with LB-62D (E9018-G) for filling passes. Since then LB-52U has remained highly reputed due to its unsurpassed performance in the root pass welding and used continuously in such pipeline welding applications.

Figure 10: Welding test of covered electrodes on pipeline segments in the then Soviet Union in 1982.

In 1985, a metal flux-cored wire, MX-100 (E70T- 1C) (Figure 11) was developed for steel structures, industrial machinery, and construction machinery. It offered high deposition rates together with the soft arc and low spatter associated with DW-100 as well as the reduction in slag covering one finds with solid wires. To respond to the continuously increasing consumption of flux-cored wires, the production framework of the Fujisawa Plant was strengthened, and a new production line for fluxcored wires was employed at the Ibaraki Plant.

Figure 11: MX-100 was an epoch-making metal flux-cored wire suitable for steel structures, industrial machinery, and
construction machinery.

The year 1980 has been called “the first year of the robot,” because robotization started in earnest in the welding industry. Kobe Steel also began comprehensive research and development of arc welding robots, particularly for steel structures and construction machinery. In 1982, an intelligent electrically-powered robot, ARCMAN-S, was developed and marketing began in full. Since then Kobe Steel has expanded the arc welding robot business by developing not only articulated robots, but also gantry type NC robots, welding power sources, positioners, and shuttles (Figure 12).

The ARCMAN series of articulated robots and systems have seen continual improvement in welding performance to meet the needs of diverse applications, including shipbuilding and bridge construction. Two-Joint Synchronized Arc Welding System was developed for assembling steel columns in 2003.

Figure 12: An ARCMAN welding robot system consists of an intelligent articulated robot, power source, positioner, and shuttle.