A710 Gr.AのSAW用予熱 — over 2-1/2"

SAW (Submerged Arc Welding)

SAW submerges the arc beneath granular flux for highest deposition rates, flat/horizontal only. Category B in Table 5.11.

SAW on high-strength plate requires careful selection of wire-flux combinations to meet both tensile matching and toughness requirements. F8A4-EA2 or similar high-performance combinations serve Category C steels. Heat input control is particularly important on TMCP grades because SAW naturally deposits high heat input due to the deeply penetrating arc.

SAW Tips for High-Strength and TMCP Steels

For A710 Grade A precipitation-hardened low-carbon plate (0.07% max carbon, CE-IIW ~0.32–0.38), SAW F7A2-EM12K handles flat-position seam welds on naval hull panels and offshore platform node connections. The ultra-low carbon provides exceptional weldability — preheat Category B standard or Category D with H8 flux (32°F all thicknesses). Class 3 plate (hardened after fabrication) allows more liberal heat input during SAW.

Typical values for reference — always verify against your approved WPS and electrode manufacturer data.

Why SAW for A710 Gr.A at over 2-1/2"

Why SAW for A710 Gr.A at over 2-1/2"? SAW delivers 15-40 lb/hr deposition — the highest deposition rate among available processes. Position capability: flat and horizontal only. Suitability: shop only.

A710 Gr.A

ASTM A710 Grade A is a precipitation-hardened low-carbon steel plate achieving high strength through copper precipitation rather than carbon content. Class 2 (65 ksi yield, age-hardened at mill) and Class 3 (75 ksi yield, precipitation-hardened after fabrication) both feature very low carbon (0.07% max) producing a CE-IIW of approximately 0.32-0.38 — among the lowest of any high-strength steel. Table 5.11 assigns Category C for standard low-hydrogen processes and the reduced Category D preheat (32°F all thicknesses) with H8-certified consumables, reflecting the exceptional hydrogen cracking resistance of this ultra-low-carbon metallurgy. The precipitation hardening mechanism means weld thermal cycles can alter the strength in the HAZ depending on peak temperature and cooling rate, requiring attention to heat input control during procedure qualification.

A710 Gr.AとSAWでこの予熱が必要な理由

Precipitation-hardened low-carbon plate with multiple category paths. The higher strength level of this steel places it in Category C of Table 5.11, which carries elevated preheat requirements compared to Category B grades. At 300°F minimum with SAW, the submerged arc process with granular flux produces controlled hydrogen levels, with flux condition being the primary variable, but the preheat must still ensure the cooling rate stays slow enough to prevent hydrogen-induced cracking in this higher-hardenability material.

A710 Gr.Aの代表的な適用例

Found in naval hull plates, military vehicle armor brackets, offshore platform node connections, heavy-lift crane boom sections, and mine hoist drum shells. A710 Gr.A precipitation-hardened plate offers a rare combination of high strength and exceptional weldability at low carbon equivalent (CE-IIW approximately 0.32-0.38). The multiple thickness-dependent category paths (B, C, and D with H8) reflect its complex metallurgical response to different section sizes. Class 2 plate is age-hardened at the mill through a controlled thermal cycle, while Class 3 achieves higher strength through precipitation hardening after welding, which makes it particularly suitable for applications where extensive welding occurs before final strengthening. The distinction between Class 2 and Class 3 response to weld thermal cycles requires careful attention during procedure qualification. Plate thicknesses up to 6" are available but procurement requires extended lead times due to limited production volume.

over 2-1/2"で予熱が重要な理由

The heaviest sections demand the highest preheat in Table 5.11. Multi-pass sequences require maintaining interpass temperature throughout.

SAWとover 2-1/2"における他の鋼材

A710 Gr.AとSAW

別の組み合わせを試す

インタラクティブ予熱計算機を使用して、D1.1:2025 表5.11のあらゆる鋼材・プロセス・板厚の組み合わせを検索できます。

A710 Gr.A溶接ガイド