Precalentamiento de A709 HPS70W para SAW — 3/4" to 1-1/2"
Temperatura mínima de precalentamiento e interpaso para A709 HPS70W soldado con SAW en espesor 3/4" to 1-1/2", según AWS D1.1:2025 Tabla 5.11.
Basado en AWS D1.1:2025 Tabla 5.11 — cada valor trazado a la cláusula.
Proceso SMAW, SAW, GMAW o FCAW de bajo hidrógeno (aceros de mayor resistencia)
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.
Why SAW for A709 HPS70W at 3/4" to 1-1/2"
Why SAW for A709 HPS70W 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.
Filler Metal for SAW
Wire: EM12K or EL12 with matching flux (AWS A5.17). Common combo: F7A2-EM12K. Diameter: 3/32" or 7/64". Flux type: active (A) for single-pass, neutral (N) for multi-pass. 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.
A709 HPS70W
ASTM A709 HPS70W is the highest-strength weathering bridge steel with 70 ksi minimum yield and 85-110 ksi tensile range, used in long-span bridges and heavily loaded members where weight reduction is critical. Produced as quenched-and-tempered plate in thicknesses up to 4", its high strength places it in Category C of Table 5.11 with correspondingly higher preheat requirements. Table 5.11 footnote (b) sets a maximum preheat/interpass of 400°F for thickness up to 1-1/2” and 450°F for thicker material — this upper limit is unusual in D1.1 and exists because the Q&T microstructure can be degraded by excessive heat. The chemistry includes copper (0.25-0.40%), nickel (0.65-1.00%), and chromium (0.40-0.65%) for atmospheric corrosion resistance, with 0.19% max carbon keeping the CE-IIW in the 0.46-0.52 range.
Por qué Este Precalentamiento para A709 HPS70W con SAW
Highest-strength 70 ksi weathering bridge steel for long-span applications. 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.
Aplicaciones Típicas de A709 HPS70W
Reserved for long-span bridge main girder flanges, cable-stayed bridge edge girders, arch rib plates, high-load interchange ramp girders, and situations where reducing member depth saves clearance or reduces dead load. HPS70W enables weight savings of 20-30% versus conventional Gr.50 designs, allowing shallower girder sections that reduce embankment costs on grade-separation bridges. Flange thickness often exceeds 2”, making preheat and interpass control critical at every CJP splice and web-to-flange joint. Note that Table 5.11 footnote (b) sets maximum preheat and interpass limits of 400°F for thicknesses up to 1-1/2" and 450°F above. This upper limit is unusual in D1.1 and requires monitoring both minimum and maximum interpass throughout the welding sequence. Fabricators must use dual-readout temperature monitoring to ensure the joint stays within the qualified band. Filler metals must match the 70 ksi minimum tensile while providing weathering-compatible chemistry for exposed joints.
Por qué el Precalentamiento Importa en 3/4" to 1-1/2"
Preheat climbs at this range as thicker material slows heat dissipation, trapping hydrogen at crack-susceptible grain boundaries.
Precalentamiento Categoría C para A709 HPS70W
La Categoría C en la Tabla 5.11 aplica a aceros de mayor resistencia donde la combinación de templabilidad y tensión residual requiere un precalentamiento elevado. Para A709 HPS70W en 3/4" to 1-1/2", el precalentamiento mínimo de 150°F reduce la velocidad de enfriamiento de la soldadura para prevenir la formación de martensita susceptible al agrietamiento en la zona afectada por el calor.
Otros Aceros con SAW en 3/4" to 1-1/2"
A709 HPS70W con SAW
Prueba Diferentes Combinaciones
Usa la calculadora interactiva de precalentamiento para consultar cualquier combinación de acero, proceso y espesor de D1.1:2025 Tabla 5.11.
Guías de Soldadura de A709 HPS70W
Datos de referencia D1.1:2025. Sin afiliación con AWS.