Trailer Design Guideline > Manufacturing
Welding heat input
Strenx® hot-rolled high-strength structural steel
High-strength steels are somewhat sensitive to high heat inputs. Excessively high heat input de-creases the strength as well as the impact tough-ness of the welded joint. If the minimum yield strength of the base material must be achieved in the welded joint, the maximum recommended heat input should not exceed the values in the graph below.
Maximum recommended heat input (Q) for Strenx® 700MC in order to fulfill the minimum yield strength (Re) and impact toughness requirements at -40 °C.
The graph is valid for butt welds, welded with matching filler metal, and where the reinforcement has been removed before testing. The maximum interpass temperature is 100 °C. The heat input can be calculated according to the formula:
Q = Heat input (kJ/mm)
k = Arc efficiency (-)
U = Voltage (V)
I = Current (A)
v = Travel speed (mm/min)
The arc efficiency values are 0.8 for MAG welding and 1.0 for SAW welding. If the weld is located in a low stressed area and the impact toughness requirement is of minor importance, higher heat inputs can be used.
Strenx® cold-rolled high-strength structural steel (CR)
Strenx® CR is produced in thinner gauges, making it more difficult to increase the heat power enough to limit the heat affected zone to a level that will allow for a failure of the base material. As a rule of thumb: weld with as low a heat input as possible.
The information in this report is only applicable to SSAB’s products and should not be applied to any other products than original SSAB products.
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