Descripción
Controlled-hardness Cr-Mo alloy steel
ASTM A193 B7M Threaded Rod
Heat-treated alloy steel all-thread for pressure bolting where the design requires B7M mechanical properties, hardness control and project-specific sour-service qualification.
Descripción general del producto
ASTM A193 Grade B7M threaded rod is a chromium-molybdenum alloy-steel bolting material with mechanical-property and maximum-hardness controls that differ from standard B7. It is frequently specified for sour hydrocarbon service and other applications where controlled hardness is part of the materials strategy.
B7M marking alone does not automatically establish compliance with every NACE MR0175 / ISO 15156 or project sour-service requirement. The purchase order must identify the environmental standard, heat-treatment sequence, prueba de dureza, supplementary tests and documentation required for the finished threaded rod.
ASTM A193 B7M threaded rod specifications
| Bolting standard | ASTM A193/A193M, edición ordenada |
|---|---|
| Calificación / material | Grade B7M, chromium-molybdenum alloy steel |
| Condition | Heat treated to B7M mechanical-property and hardness requirements |
| Sistemas de hilos | ASME B1.1 UNC, UNF o 8UN; metric threads when ordered |
| Rango de tallas | 1/4–4 in and M6–M100 typical; exact range subject to testing and availability |
| Tuercas compatibles | ASTM A194 Grade 2HM commonly specified, subject to project requirements |
| Sour-service option | NACE MR0175 / ISO 15156 and purchaser supplements only when explicitly ordered |
| Opciones de acabado | Plano, black or qualified project coating; coating and lubricant reviewed together |
Dimensiones finales, tolerancias, tratamiento térmico, revestimiento, Los criterios de prueba y aceptación siguen la orden de compra confirmada y la edición estándar aplicable.. La disponibilidad depende del diámetro., longitud, Forma del hilo y cantidad de producción..
¿Por qué especificar este material??
B7M is considered when the materials engineer needs an established Cr-Mo bolting grade with controlled hardness. It is not simply a lower-cost alternative to corrosion-resistant alloy bolting; environment, estrés, cathodic protection and service temperature still govern selection.
nota de ingeniería
Corte, thread production and heat treatment must follow the ordered standard and project sequence. Confirm whether hardness testing is required on each piece, each end or by lot, and whether testing must occur after all manufacturing operations.
Aplicaciones típicas
Calidad, inspección y documentación
Procurement should define hardness frequency, pruebas mecanicas, heat-treatment traceability and any sour-service supplements. A complete B7M package commonly includes MTC, hardness results, thread inspection and coating records.
- EN 10204 3.1 certificado de prueba de materiales
- Número de calor y trazabilidad de lotes.
- Composición química y propiedades mecánicas.
- Inspección dimensional y calibrado de roscas.
- PMI para aleaciones de níquel y acero inoxidable cuando se solicita
- Espesor del recubrimiento o inspección de la superficie cuando corresponda.
- Inspección de terceros y pruebas adicionales por acuerdo
- Marcado de exportación y embalaje marítimo.
Información requerida para la cotización
- Grado de material, Material aplicable/estándar de empernado y edición requerida.
- Diámetro, serie de hilos, paso y clase de rosca o tolerancia
- Longitud total, Requisitos y cantidad de extremos cortados.
- Tratamiento térmico, acabado superficial o sistema de recubrimiento
- Tuercas y arandelas a juego, incluidos los requisitos anti-excoriación
- Plan de inspección, MTC, PMI, Requisitos de ECM y testigos de terceros
- Destino de entrega, embalaje y horario requerido
Preguntas frecuentes
Es ASTM A193 B7M automatically NACE compliant?
No. B7M provides grade-specific hardness and mechanical requirements, but NACE MR0175 / ISO 15156 suitability depends on the exact environment, forma del producto, heat treatment and project requirements.
What nut grade is commonly used with B7M?
ASTM A194 Grade 2HM nuts are commonly specified. The engineer must confirm nut grade, dureza, coating and thread compatibility.
How does B7M differ from B7?
B7M has lower strength and controlled maximum hardness requirements compared with B7, together with grade-specific manufacturing and testing provisions.
Can B7M threaded rod be fluoropolymer coated?
Yes when permitted by the design and qualified purchase specification. Coating thickness, cure temperature, thread fit, lubricant and installation torque require coordinated control.
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