All abrasion resistant steels require pre-heating before welding except ENDURA and ENDURA Dual with Titanium carbides. This involves heating the steel to a specific temperature before welding, in its entirety, or at a minimum in the area surrounding the weld joint.
The pre-heat temperature will vary depending on the carbon/alloy content, thickness, welding speed, wire diameter, and ambient temperature just to name a few considerations. Generally pre-heating should be around 100-150 °C.
Why is Pre-Heating Abrasion Resistant Steel So Important?
The main reason pre-heating is required for most abrasion resistant steels is to avoid cold cracking. Cold cracking is a time delayed phenomenon in the heat affected zone (HAZ) of the base plate and/or in the weld metal thought to be caused by an input of hydrogen.
A means to avoiding such cracking is pre-heating. It delays the cooling of the weld region and weld metal thereby minimizing input of hydrogen in the weld resulting in Cold Cracking.
How is Hydrogen Introduced?
Hydrogen is often introduced during the manufacture process from operations such as quenching, or cleaning. Hydrogen may also be introduced over time through environmental exposure (soils and chemicals, including water) and corrosion.
What Sets ENDURA and ENDURA Dual Apart from Other Abrasion Resistant Steels?
ENDURA and ENDURA Dual are quenched in oil, which is an expensive process compared to other abrasion resistant steels which are quenched in water. Consequently, they can be welded with no pre-heating (up to 2”) and with low hydrogen rod, conditional on being welded at room temperature. This saves significant time and money spent in pre-heating the plate.
A Few Final Pre-Heating Tips
To further avoid cold cracking, it is recommended that welding surfaces be cleaned of oil, grease or other contaminates. Edges should be ground to remove residual oxides, dross or slag. Welding should also be done in an alternate “stitch” pattern instead of a continuous weld pattern.