A1066 Gr.50 Preheat for SAW — 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 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.

Why SAW for A1066 Gr.50 at over 2-1/2"

Why SAW for A1066 Gr.50 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.

Filler Metal for SAW

Wire: EM12K or EL12 with matching flux (AWS A5.17). Common combo: F7A2-EM12K. Diameter: 3/32" or 7/64". AWS A5.17 Figure 1U uses A for as-welded and P for PWHT, not flux activity. Annex A6.1 defines active versus neutral flux by weld-metal Mn and Si change with arc voltage (Wall Neutrality Number); primary use of neutral fluxes is multipass welding and of active fluxes is single-pass welds. Voltage: 28-34V. Current: 400-800A depending on joint size. Travel: 12-24 ipm.

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

A1066 Gr.50

ASTM A1066 Grade 50 is a high-strength low-alloy plate (50 ksi yield, 65 ksi minimum tensile) with options for enhanced toughness and weldability through controlled chemistry and supplementary requirements. It falls under Category B for standard low-hydrogen processes and qualifies for the reduced Category E preheat (50°F up to 1”, 120°F above 1”) with H8-certified consumables. The specification includes S-series supplementary requirements for impact testing at various temperatures, allowing engineers to select the toughness grade appropriate for their service environment. Carbon content is limited to 0.20% max with CE-IIW controlled to approximately 0.38-0.44. A1066 Gr.50 competes with A572 Gr.50 plate in applications where the H8 preheat reduction provides meaningful fabrication cost savings on thick-section joints.

Why This Preheat for A1066 Gr.50 with SAW

HSLA plate with H8-eligible Category E reduced preheat option at 50 ksi. This steel is prequalified only with low-hydrogen processes under Table 5.11. With SAW, the submerged arc process with granular flux produces controlled hydrogen levels, with flux condition being the primary variable. The 225°F minimum preheat balances the steel’s strength level and carbon equivalent against the hydrogen control provided by SAW. Non-low-hydrogen SMAW is not an option for this grade under D1.1 prequalified WPS.

Typical Applications for A1066 Gr.50

Applied in bridge plate girder webs where enhanced toughness is required beyond A709 Gr.50, cold-region building plate elements, heavy equipment support platforms, wind turbine tower flanges, and modular building frames. A1066 Gr.50 with H8 consumables qualifies for Category E reduced preheat (50°F up to 1", 120°F above 1"), offering a cost advantage over standard Category B procedures on thick plate where preheat time is a significant production bottleneck. Plate procurement requires specifying the supplementary toughness requirements (S-series) appropriate for the service temperature — S30 for -30°F, S50 for -50°F testing. The H8 preheat reduction becomes increasingly valuable as plate thickness increases, saving 30-60 minutes of preheating time per joint on material over 1 inch. For a bridge fabricator welding 200+ stiffener fillet welds per girder, the cumulative preheat savings from H8 consumables can reduce shop cycle time by 15-20% compared to full Category B procedures.

Why Preheat Matters at over 2-1/2"

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

Other Steels with SAW at over 2-1/2"

A1066 Gr.50 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.

A1066 Gr.50 Welding Guides