Precalentamiento M270M HPS485W — H16, Low HI, > 60 mm: 400°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.

Entendiendo el Precalentamiento 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 H16 hydrogen designation and this heat input band requires 400°F minimum preheat at > 60 mm (> 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.

Dónde se Usa M270M HPS485W / M270 HPS70W

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.

Control de Hidrógeno H16 para M270M HPS485W / M270 HPS70W

HPS485W (HPS70W) at H16 represents the highest-risk FC scenario for this grade — the combination of high strength, high hardenability, and high hydrogen demands the maximum preheat in Tables 12.6/12.7. Production scheduling must account for extended preheat soak times at every joint. Many fabricators refuse H16 on HPS485W, requiring H4 or H8 in their shop standards.

Por qué el Precalentamiento Importa en > 60 mm (> 2½ in)

Material over 65 mm (2-1/2 in) includes the heaviest bridge girder flanges and box-section walls. Table 6.3 requires 110°C (225°F) for both groups at this thickness. Extended preheat soak time is necessary to achieve uniform through-thickness temperature. FC preheat for the heaviest sections reaches 180–200°C (350–400°F) at the H16 hydrogen level.

M270M HPS485W / M270 HPS70W en > 60 mm (> 2½ in)

HPS485W (HPS70W) above 65 mm is the heaviest plate used in high-performance bridge construction. Flange widths reach 750–900 mm (30–36 in), with splice welds requiring 100+ passes over multiple shifts. Temperature management becomes the dominant production variable — too cold risks cracking, too hot risks softening the Q&T microstructure. Fabricators invest in automated temperature monitoring systems with data logging for FC traceability.

Mayor Precalentamiento con Designación H16

Los consumibles H16 permiten hasta 16 mL de hidrógeno difusible por 100g — el nivel más alto permitido para soldadura FC de puentes. En > 60 mm (> 2½ in) con aporte térmico 1.2–2.0 kJ/mm, el precalentamiento de 400°F (200°C) compensa el mayor potencial de hidrógeno.

Otros Aceros de Puente en H16 1.2–2.0 kJ/mm · > 60 mm (> 2½ in)

M270M HPS485W / M270 HPS70W en H16 1.2–2.0 kJ/mm

Prueba Diferentes Combinaciones

Usa la Calculadora de Precalentamiento D1.5 para Puentes para consultar cualquier acero AASHTO M270, nivel de hidrógeno y combinación de aporte térmico. También consulta la Calculadora de Precalentamiento D1.1 para acero estructural.

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