A709 HPS50W SAW 예열 — 1-1/2" to 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 with F7A2-EM12K wire/flux delivers the highest deposition rates for flat-position fillet welds on building steel. Typical parameters: 500-700 amps, 28-32 volts, 18-30 IPM travel speed. Flux consumption runs approximately equal to wire consumption by weight. Unfused flux recovery and recycling systems are standard in production shops to control consumable costs.

SAW Tips for Common Structural Steels

For A709 HPS50W high-performance weathering bridge steel (50 ksi yield, CE-IIW ~0.38–0.42), SAW with weathering-compatible wire (F7A2-EM12K-W) handles girder web-to-flange fillet welds and flange butt splice groove welds. The lower CE-IIW compared to conventional A588 weathering steel means SAW preheat sensitivity is reduced, lowering the risk of HAZ cracking on thick flange splices during cold-weather shop fabrication.

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

Why SAW for A709 HPS50W at 1-1/2" to 2-1/2"

Why SAW for A709 HPS50W at 1-1/2" to 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.

A709 HPS50W

ASTM A709 HPS50W is a high-performance weathering steel (50 ksi yield, 70 ksi minimum tensile) developed specifically for unpainted bridge construction. The HPS designation indicates enhanced weldability through lower carbon (0.11% max), controlled sulfur (0.006% max with calcium treatment), and copper-nickel-chromium alloying for atmospheric corrosion resistance. These chemistry controls reduce the CE-IIW to approximately 0.38-0.42, well below conventional weathering steels. It falls under Category B in Table 5.11. The FHWA-funded development program that created HPS grades (starting in the 1990s) aimed to eliminate the weldability problems, lamellar tearing, and inconsistent toughness that plagued earlier weathering steel bridge designs. HPS50W has largely replaced conventional A709 Gr.50W in new unpainted bridge designs.

SAW를 사용한 A709 HPS50W의 이 예열 이유

High-performance weathering bridge steel with enhanced weldability 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 150°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.

A709 HPS50W의 일반적인 용도

Deployed in unpainted bridge plate girders across humid or coastal environments, curved girders on interchange ramps, signature pedestrian bridges in architectural applications, and rural highway bridges where lifecycle paint costs exceed the HPS premium. The enhanced weldability of HPS50W reduces fabrication risk at flange splices and allows wider groove angles with reduced risk of lamellar tearing in thick flange plates through controlled sulfur and inclusion shape control via calcium treatment. The chemistry control (0.11% max carbon, controlled sulfur at 0.006% max) differentiates HPS from conventional weathering grades. Material cost premium over standard A709 Gr.50W is typically 15-25% per ton but eliminates lifetime repainting cycles estimated at $15-25 per square foot every 20-25 years. The lower CE-IIW of HPS50W compared to conventional weathering grades means it welds with less preheat sensitivity, reducing reject rates on thick flange CJP splices during cold-weather bridge fabrication.

1-1/2" to 2-1/2"에서 예열이 중요한 이유

Heavy plate with significant restraint and thermal mass — preheat is critical to maintain slow cooling for hydrogen escape.

1-1/2" to 2-1/2"에서 SAW를 사용하는 다른 강재

A709 HPS50W, SAW

다양한 조합 시도

인터랙티브 예열 계산기를 사용하여 D1.1:2025 표 5.11의 모든 강재, 공정, 두께 조합을 조회하세요.

A709 HPS50W 용접 가이드