Among stainless steel welding wires, ER312 occupies a unique position. Classified under AWS A5.9, its 29 % chromium / 9 % nickel composition gives it a highly alloyed, ferrite-rich weld deposit that no standard 308 / 309 / 316 wire can match for crack resistance.
Primary Uses of ER312
- Dissimilar metal welding - stainless steel to carbon steel, low alloy steel, or tool steel
- Welding of unknown base metals on maintenance and repair jobs
- Buttering layers on tool steel, spring steel, or manganese steel before final capping
- Hardfacing / buildup on wear-prone components
- Repair of cracked cast steel and hard-to-weld alloys
Why the 29/9 Composition Matters
The high chromium and high ferrite content lets ER312 absorb carbon and other alloying elements from the base material without becoming brittle. That is exactly what happens when you weld onto tool steel, high-carbon steel, or cast steel - and it is the reason ER312 survives conditions that would crack a standard austenitic filler.
Where ER312 Is Not the Right Choice
ER312 is not the correct filler for routine 304 / 316 stainless welds where color match and standard corrosion resistance are the priority. In those cases, use ER308L or ER316L instead.
Sourcing Certified ER312
Ask your supplier for AWS A5.9 test certificates, ferrite number reports, and full batch traceability. Dayang Welding produces ER312 on a dedicated stainless line with mill test reports on every batch.
