Why hardened material is a problem
Hardened steel does not fail like mild steel, and welding is where that difference shows.
- Heat can soften. The area around a weld gets hot, and that can undo the hardening in the zone next to it.
- Rapid cooling can crack. Hard material cooling quickly is prone to cracking, especially around a crack that already exists.
- Stress is added. The weld shrinks as it cools and pulls on the surrounding metal.
- Carbide is a separate issue. A carbide insert on an edge is joined by a different process, and heating it can damage the joint.
When replacement is the safer choice
| Situation | Lean toward |
|---|---|
| Crack in the edge body or near a bolt hole | Replace |
| Carbide insert loose or missing | Replace the edge or the insert section per the maker |
| Edge bent and cracked | Replace |
| Worn corner on a plain steel edge, no cracks | Ask the maker; build-up may be allowed in some designs |
| Weld repair on the moldboard (not the edge) | Separate question; use a qualified welder |
Questions to ask before any weld
Hardened edge repair is one of the few jobs where the wrong answer is easy to get and expensive to discover.
- Does the edge maker allow welding, and with what procedure? The answer may be no, and that answer matters more than the weld.
- What material is it, and is it heat treated? You cannot choose a procedure without the grade.
- Who is the welder, and what is their qualification for this material? A qualified welder on the wrong steel is still the wrong welder.
- What is the inspection plan after welding? Cracks appear later, and the plan decides who finds them.
If in doubt
A new edge costs less than a failed repair on the road. If a welded edge is used, inspect it more often, and log it as a repaired part.
What a repair record should contain
If you do repair a part, write down the date, location of the weld, who did it, which process was used and how it was inspected afterwards. Tag the part so that the next person knows. Check it at every inspection and retire it at the first sign of a new crack. A repaired part with no record is a hidden risk, and a record lets you review how repairs performed.
Boundary: general explanation only; not a welding procedure or engineering advice. Consult the edge maker and a qualified welding engineer.
Further reading on this site.
Hardened Steel vs Carbide in Abrasive Service: Choosing by Wear Mechanism ↗Can we reuse a drawing after the mounting rail has been repaired? ↗Carbide snow plow blades ↗AQL Sampling for Incoming Edges: How to Choose a Sample Size ↗Brinell vs Rockwell on Steel Edges: How to Read a Hardness Spec Line ↗Rubber at Low Temperature: What ASTM D2137 Covers and What to Ask a Maker ↗
