A710 Gr.A Preheat for SAW — 3/4" to 1-1/2"

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 selects wire-flux combinations by the steel's Table 5.6 base-metal group, not its Table 5.11 preheat category: Table 5.7 marks AWS A5.17 carbon-steel combinations N/A for Groups III, IV and V and lists AWS A5.23 low-alloy combinations such as F8AX-E(C)XXX-A2 for Group III and F9AX-E(C)XXX-A2 for Group IV. 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. Table 5.11 splits A710 Gr.A by class and thickness: Class 2 over 2 in [50 mm] is Category B; Class 2 up to 2 in [50 mm] and Class 3 over 2 in [50 mm] are Category C; every class is Category D with H8 electrode-flux combinations (32°F [0°C] all thicknesses). With standard wire-flux combinations this calculator shows the Category C value, which applies only to Class 2 up to 2 in [50 mm] or Class 3 over 2 in [50 mm]; Class 1, and Class 3 up to 2 in, are listed only under Category D with H8. 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. This 150°F (65°C) value applies only to A710 Grade A Class 2 (up to 2 in [50 mm]); Class 1 and Class 3 at this thickness have no Table 5.11 row without H8 and are listed only under Category D with H8.

Why SAW for A710 Gr.A at 3/4" to 1-1/2"

Why SAW for A710 Gr.A at 3/4" to 1-1/2"? 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 lists it by class and thickness: with standard low-hydrogen processes, Category C covers Class 2 up to 2 in [50 mm] and Class 3 over 2 in [50 mm] and Category B covers Class 2 over 2 in [50 mm], while every class takes 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. This 150°F (65°C) value applies only to A710 Grade A Class 2 (up to 2 in [50 mm]); Class 1 and Class 3 at this thickness have no Table 5.11 row without H8 and are listed only under Category D with H8.

A710 Grade A Table 5.11 split

A710 Grade A is listed by class and thickness in AWS D1.1:2025 Table 5.11. The Category C value on this page applies only to Class 2 up to 2 in [50 mm] and Class 3 over 2 in [50 mm]. Class 2 over 2 in [50 mm] is Category B. Class 1, and Class 3 up to 2 in [50 mm], have no Table 5.11 row without H8 consumables and are listed only under Category D with H8, so this value does not apply to them. Confirm the class before using it.

Why This Preheat for A710 Gr.A with SAW

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 150°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. This 150°F (65°C) value applies only to A710 Grade A Class 2 (up to 2 in [50 mm]); Class 1 and Class 3 at this thickness have no Table 5.11 row without H8 and are listed only under Category D with H8.

Typical Applications for A710 Gr.A

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.

Why Preheat Matters at 3/4" to 1-1/2"

Preheat climbs at this range as thicker material slows heat dissipation, trapping hydrogen at crack-susceptible grain boundaries.

Category C Preheat for A710 Gr.A

Category C in Table 5.11 applies to higher-strength steels where the combination of hardenability and residual stress requires elevated preheat. For A710 Gr.A at 3/4" to 1-1/2", the 150°F minimum preheat slows the weld cooling rate to prevent formation of crack-susceptible martensite in the heat-affected zone. Maintaining interpass temperature at or above this minimum is especially critical for multi-pass welds on restrained joints. This 150°F (65°C) value applies only to A710 Grade A Class 2 (up to 2 in [50 mm]); Class 1 and Class 3 at this thickness have no Table 5.11 row without H8 and are listed only under Category D with H8.

Other Steels with SAW at 3/4" to 1-1/2"

A710 Gr.A with SAW

Try Different Combinations

Use the interactive preheat calculator to look up any steel, process, and thickness combination from D1.1:2025 Table 5.11.

A710 Gr.A Welding Guides