These mechanical properties make P355NH suitable for high-temperature and high-pressure applications, ensuring the strength and integrity of the vessel or boiler in which it is used.

The mechanical properties of P355NH and P355GH, which are both carbon and low alloy steel grades, are as follows:

1. Tensile strength: The tensile strength of P355NH is typically between 490-630 MPa, while for P355GH, it is between 510-650 MPa. Tensile strength refers to the maximum amount of stress a material can withstand without breaking or deforming permanently.

2. Yield strength: The yield strength of P355NH is generally around 355 MPa, while for P355GH, it is approximately 355-510 MPa. Yield strength is the amount of stress at which a material begins to deform permanently or show plastic behavior after being subjected to external forces.

3. Elongation: The elongation of P355NH is typically 20% on a gauge length of 25 mm, while for P355GH, it is around 22% on a gauge length of 25 mm. Elongation is a measure of the ductility of a material and represents the percentage increase in length before fracture.

4. Impact toughness: P355NH and P355GH both exhibit good impact toughness, making them suitable for applications involving low-temperature environments or dynamic loading conditions. Impact toughness refers to the ability of a material to absorb energy during sudden loading or impact.

5. Hardness: The hardness values of P355NH and P355GH depend on the heat treatment condition and can range between 130-170 HB (Brinell hardness) or 120-160 HV (Vickers hardness). Hardness is an indication of a material’s resistance to deformation or indentation.

It is important to note that these mechanical properties may vary depending on the specific manufacturing process, heat treatment, and composition of the steel. Therefore, it is recommended to consult the relevant technical standards or datasheets for precise and up-to-date information.