Introduction To NM550

Introduction to NM550

Consider the following recommended values when cold forming (t for plate thickness)

Thermoforming:

The hardness is obtained by accelerated cooling from the austenitizing temperature. After thermoforming, only re-quenching can restore the hardness. It can be expected that the hardness obtained by re-quenching will be different from the hardness measured at the factory, because the quenching equipment used in the production of steel plates and the quenching equipment owned by the processing plant have differences in capacity. The hardness of the steel plate heated to about 200 C will not decrease significantly (the shorter time can also reach 2500C).

Flame cutting and welding:

Flame cutting should follow the following minimum preheating temperature: plate thickness 25 ~ 75mm, 75℃; Plate thickness >70mm, 125℃.

For manual arc welding, an alkaline coated electrode with low residual moisture should be selected (if necessary, it should be dried according to the requirements of the electrode manufacturer). In addition, the following suggestions should also be considered:

In order to prevent weld cracking when the structural rigidity is high, it is generally recommended to take a preheating temperature of 140~1900 for the thick steel plate above 15 mm. Preheating above 200 C must be avoided, as it will reduce the hardness (see figure below).

Weld filler should be as soft as possible within the range of load bearing structure and wear bearing of weld.

Minimum bending radius Minimum die opening size

Transverse 7t 14t

Vertical 9t 18t

Heat treatment:

The figure below shows the general change in hardness or strength with heat treatment temperature:

Tempering temperature 0C

It should be noted that the heat treatment of 300~4000C May reduce the toughness of the steel plate at room temperature.

Quality inspection

Productive Process

Packing&Delivery