Pré-aquecimento M270M HPS485W — H4, Low HI, 40–60 mm: 300°F

M270M HPS485W / M270 HPS70W

AASHTO M270M HPS485W (M270 HPS70W) is a high-performance weathering steel with 485 MPa (70 ksi) yield, used in long-span bridge girder flanges and heavily loaded members where weight reduction is critical. Produced as quenched-and-tempered plate up to 100 mm (4 in) thick. The high strength level places it in NFC Group 2 (Table 6.3) with higher minimum preheat than Group 1. FC preheat follows Tables 12.6/12.7 alongside the 345W grades but at higher temperatures reflecting the increased hardenability. Maximum interpass per Table 6.4 is 230°C (450°F) to protect the Q&T microstructure.

Entendendo o Pré-aquecimento FC para M270M HPS485W / M270 HPS70W

High-performance 485 MPa (70 ksi) weathering bridge steel. Under D1.5 fracture-critical requirements (Clause 12), the combination of H4 hydrogen designation and this heat input band requires 300°F minimum preheat at 40–60 mm (1½–2½ in). Lower hydrogen levels (H4 < H8 < H16) allow lower preheat because less hydrogen enters the weld deposit. Similarly, higher heat input reduces preheat requirements because slower cooling rates give hydrogen more time to diffuse out.

Onde M270M HPS485W / M270 HPS70W é Usado

Used in long-span bridge main girder flanges, cable-stayed bridge edge girders, and heavily loaded interchange ramp girders where weight reduction is critical. Enables 20–30% weight savings versus Gr.345 designs, allowing shallower girder sections that reduce embankment costs. Flange thickness often exceeds 50 mm (2 in), making preheat and interpass control critical at every CJP splice. Fabricators must use dual-readout temperature monitoring to ensure joints stay within the qualified range between minimum preheat and maximum interpass.

Controle de Hidrogênio H4 para M270M HPS485W / M270 HPS70W

For HPS485W (HPS70W), specifying H4 consumables is a strategic choice that significantly reduces preheat costs on thick flange splices. At 40+ mm flange thickness, every 25°F reduction in required preheat saves approximately 15–20 minutes per splice in heating time, directly impacting the critical-path schedule of bridge girder fabrication.

Por que o Pré-aquecimento Importa em 40–60 mm (1½–2½ in)

Material from 40 to 65 mm (1-1/2 to 2-1/2 in) covers heavy girder flanges, thick splice plates, and main member plate. This is the critical thickness range for bridge fabrication — preheat reaches 65°C (150°F) for Group 1 and 80°C (175°F) for Group 2. FC preheat at this thickness can exceed 200°C (400°F) depending on hydrogen level and heat input.

M270M HPS485W / M270 HPS70W em 40–60 mm (1½–2½ in)

HPS485W (HPS70W) at 40–65 mm represents the critical design case for long-span cable-stayed and continuous girder bridges. Flange plates this thick with 70 ksi yield can support spans exceeding 300 feet (90 m) with conventional plate girder construction. FC preheat at this thickness tier is substantially higher than Group 1 grades, and dual-readout temperature monitoring is mandatory to ensure compliance with both preheat minimum and interpass maximum.

Consumíveis Certificados H4 para Soldagem FC de Pontes

O designador suplementar H4 certifica que o consumível deposita no máximo 4 mL de hidrogênio difusível por 100g de metal depositado. Para fratura crítica M270M HPS485W / M270 HPS70W em espessura 40–60 mm (1½–2½ in) com aporte de calor 1.2–2.0 kJ/mm, os consumíveis H4 alcançam o menor pré-aquecimento de 300°F (150°C) nas tabelas FC.

Outros Aços de Ponte em H4 1.2–2.0 kJ/mm · 40–60 mm (1½–2½ in)

M270M HPS485W / M270 HPS70W em H4 1.2–2.0 kJ/mm

Experimente Diferentes Combinações

Use a Calculadora de Pré-aquecimento D1.5 para Pontes para consultar qualquer aço AASHTO M270, nível de hidrogênio e combinação de aporte de calor. Veja também a Calculadora de Pré-aquecimento D1.1 para aço estrutural.

Guias Relacionados