Q390MB is a high-strength low-alloy structural steel defined by the Chinese national standard GB/T 1591-2018 "High Strength Low Alloy Structural Steels," known for its excellent strength and good weldability. The "MB" indicates that the material has undergone Thermo-Mechanical Controlled Processing (TMCP), which helps enhance both the strength and toughness of the material.

Internationally, there is no direct equivalent material for Q390MB, but similar foreign standard materials can be identified based on its chemical composition and mechanical properties. Below are some potential international equivalents:

1. **European Standard (EN)**: The chemical composition and performance of Q390MB may resemble S460M or S460ML under EN 10025-6. These materials are also high-strength structural steels with similar yield and tensile strengths.

2. **ASTM Standard**: Q390MB may be comparable to ASTM A572 Grade 65 or A709 Grade 50W, which are high-strength low-alloy steels defined in U.S. standards.

3. **Japanese Industrial Standard (JIS)**: Q390MB may be similar to SM520B or SM520C under JIS G 3106, which are steels for welded structures as defined in Japanese standards.

4. **German Industrial Standard (DIN)**: Q390MB may correspond to St 52-3 U under DIN 17100 or W St E 355 under DIN 17102, which are structural steels defined in German standards.

5. **British Standard (BS)**: Q390MB may be analogous to Grade 55D or 50D under BS 4360, which are steels for welded structures as defined in British standards.

In practical applications, specific engineering requirements and usage environments must be considered when selecting substitute materials. Steel standards from different countries may vary in chemical composition, mechanical properties, impact test temperatures, and other aspects. Therefore, engineers and procurement personnel should conduct detailed comparisons of the specific requirements of relevant standards and perform material testing when necessary to ensure that the selected material meets engineering needs and safety standards. Additionally, considering the demands of international trade and project cooperation, using internationally recognized material standards can help reduce obstacles in material substitution and certification processes.