Electrode comparison

E309L vs E410

E309L deposits tough austenitic weld metal with no heat treatment; E410 deposits air-hardening martensitic metal that requires preheat and post-weld tempering.

E309L vs E410 at a glance

	E309L	E410
AWS specification	AWS A5.4/A5.4M	AWS A5.4/A5.4M
Process	Stick (SMAW)	Stick (SMAW)
Form	Covered electrode	Covered electrode
Tensile strength (min)	75 ksi	75 ksi
Yield strength (min)	45 ksi	55 ksi
Elongation (min)	30%	20%
Impact toughness	Not required by the specification	Not required; properties depend heavily on post-weld heat treatment
Polarity	DCEP, AC	DCEP, AC
Positions	Flat, Horizontal, Vertical, Overhead	Flat, Horizontal, Vertical, Overhead
Penetration	Shallow to medium	Medium
Deposition rate	Medium	Medium
Coating / core	Lime-titania (-16)	Lime or lime-titania
Slag	Self-lifting, must be fully removed between passes	Moderate, releases readily
Shielding gas	None — self-shielding	None — self-shielding
Storage	Dry storage, rod oven after opening — same discipline as E308L.	Dry storage and a rod oven at 250–300 °F (120–150 °C) after opening — hydrogen cracking is a real risk with martensitic deposits.
Primary use	Joining austenitic stainless to carbon or low-alloy steel	Repair and joining of 410 martensitic stainless components

Which should you use?

The practical question here is usually how to weld 410 base metal or build a wear overlay. E410 matches 410 chemistry and gives a hard, wear-resistant, magnetic deposit — but it air-hardens to martensite, so it needs 350–450 °F preheat, maintained interpass temperature and post-weld tempering, or it cracks. E309L gives a ductile austenitic deposit that needs none of that, which is why it is frequently used to weld 410 when heat treatment is impossible. The trade is that the joint no longer matches the base metal's properties.

Choose E309L when

Joints that cannot be preheated or heat treated
Dissimilar and repair welding
Where weld ductility matters more than hardness

Choose E410 when

Matching 410 base metal with full heat treatment available
Hardfacing valve seats, shafts and wear surfaces
Applications needing a hard, magnetic deposit

Amperage compared

Diameter	E309L	E410
3/32 in (2.4 mm)	40–80 A	40–80 A
1/8 in (3.2 mm)	65–110 A	70–110 A
5/32 in (4.0 mm)	95–150 A	100–150 A
3/16 in (4.8 mm)	130–190 A	130–190 A

Ranges are typical starting points. Diameters listed for only one electrode are shown as — for the other.

E309L vs E410 — common questions

Can you weld 410 stainless with E309L?

Yes, and it is common practice when preheat and post-weld heat treatment are not possible. The weld will be austenitic and ductile rather than matching the base metal, so check that the design accepts that.

Does E309L need preheat?

Not for its own sake — austenitic deposits do not air-harden. Preheat may still be required by the base metal, as when welding to 410 or to thick carbon steel.

Which deposit is magnetic?

E410 is strongly magnetic. E309L is austenitic and only weakly magnetic from its delta ferrite content.

Full specifications

E309L

AWS A5.4/A5.4M

E309L is the dissimilar-metal electrode — its extra chromium and nickel survive dilution when joining stainless to carbon steel or laying a stainless overlay.

E410