選択 の 溶接 材料 のための A333Gr3 極低温 パイプ

(1) アルミニウム 脱酸 鋼
アルミニウム 脱酸 鋼 は a steel type that is very sensitive to the influence of post-welding cooling rate. Most of the welding electrodes used in manual arc welding of aluminum deoxidized steel use Si-Mn low-hydrogen welding electrodes or 1.5% Ni-based or 2.0% Ni-based welding electrodes。

order to reduce the welding heat input, aluminum deoxidized steel generally uses only multi-layer welding with fine electrodes Less than or equal to ¢3~3.2mm, so that the secondary thermal cycle of the upper weld bead can be used to refine the grains.

impact toughness of the weld metal deposited with Si-Mn welding electrodes at 50 degree will decrease sharply as the heat input increase. For example, when the heat input increase from 18KJ/cm to 30KJ/cm, the toughness will lose more than 60%. 1.5% Ni series and 2.5% Ni series electrodes are not very sensitive to this, so it is best to use this type of electrode for welding.

水中 アーク 溶接 は a commonly used automatic welding method for aluminum deoxidized steel. The best welding wire used for submerged arc welding is one containing 1.5~3.5% nickel and 0.5~1.0% molybden。

一致 に the literature, using 2.5% Ni-0.8% Cr-0.5% Mo or 2% Ni welding wire, combined with appropriate flux, the charpy toughness value of the weld metal at -55 degree can reach an average of 56-70J (5.7 ~7.1Kgf.m). Even when using 0.5% Mo welding wire and manganese alloy alkaline flux, as long as the heat input is controlled below 26KJ/cm, weld metal with ν∑-55=55J (5.6Kgf.m) can still be produce。

When selecting flux, attention should be paid to the matching of Si and Mn in the weld metal. Experimental proof. Different Si and Mn contents in the weld metal will cause great changes in the Charpy toughness value. The Si and Mn contents with the best toughness values are {{0}}.1~0.2% Si and 0.7~1.1% Mn. When selecting the welding wire and This should be noted when fluxing.

タングステン アーク 溶接 および melting arc welding are less commonly used in aluminum deoxidized steel. The above-said welding wires for submerged arc welding can also be used for argon arc welding。

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

(2) 2.5Ni steel and 3.5Ni
水中に沈められる アーク welding or MIG welding of 2.5Ni steel and 3.5Ni steel can generally be welded with the same welding wire as the base material. Mn is a hot cracking inhibitory element in low-nickel low-temperature steel. Keeping the manganese content in the weld metal at around 1.2% is very beneficial to preventing hot cracks such as arc crater cracks. This should be taken into consideration when selecting the combination of welding wire and flux.
3.5Ni steel has a greater tendency to temper embrittlement, so after post-weld heat treatment (for example, 620 degree × 1 hour, then furnace cooling) to eliminate residual stress, ν∑-100 will drop sharply from 3.8 Kgf.m to 2.1Kgf.m can no longer meet the requirements. The weld metal deposited with 4.5% Ni-0.2% Mo welding wire has a much smaller tendency to temper embrittlement. The above difficulties can be avoided by using this welding wire.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

(3) 9Ni 鋼
9Ni steel usually undergoes heat treatment by quenching and tempering or twice normalizing and tempering to maximize its low-temperature toughness. However, the weld metal of this type of steel cannot be heat treated as described above. Therefore, if iron system welding materials are used, it is difficult to obtain a weld metal with low-temperature toughness comparable to that of the base metal. Currently, high-nickel welding materials are mainly used. The welds deposited by such welding materials will have a completely austenitic structure. Although it has the disadvantages of lower strength than 9Ni steel base metal and very expensive price, brittle fracture is no longer a serious problem for it.

それ can be seen from the above that since the weld metal is completely austenitic, the low-temperature toughness of the weld metal used for welding with welding rods and wires is completely comparable to that the base metal, but the tensile strength and yield point are lower than those of the base metal. Nickel-containing steel is self-hardening, so most welding rods and wires pay attention to limiting the carbon content in 注文 に 達成 良い 溶接性。
Mo is an important strengthening element in welding materials, while Nb, Ta, Ti and W are important toughening elements, and full attention has been paid to the selection of welding materials.
いつ the same kind of welding wire is used for welding, the strength and toughness of the submerged arc welding metal are worse than those of MIG welding. This may be due to the slow cooling rate of the weld and the possibility of impurities or Si infiltrating from the flux. 。