WeldMaster SS400 welding rod: which electrode, wire and amps?
SS400 is a plain JIS structural steel, so weld it like mild steel: a low-hydrogen stick rod or ER70S-6 wire is the usual match. For 6 mm plate, WeldMaster's mild steel tables give 130 – 210 A with a 5/32" E7018 rod.
What is SS400, and is it stainless?
No, the SS stands for steel structure, not stainless. SS400 is a general structural plate and bar grade from the Japanese standard, with a tensile strength of about 400 MPa. It is commonly treated as comparable to A36 and to European S235 or S275 structural steel. Treat that as a rough match and check the paperwork before you rely on it.
WeldMaster has no SS400 entry; it does not know JIS grades. The recommended approach is to use it under Mild Steel, with the A36 Mild Steel values as the closest preset.
Which electrode does it want?
The Filler Selector shows, for Mild Steel, ER70S-6 for MIG, ER70S-2 for TIG, E71T-1 or E71T-11 for flux core and E7018 for stick. Those are AWS classes; Japanese rod packets carry JIS codes such as D4316 (low hydrogen) or D4313 (soft arc, light penetration). D4316 is usually taken as the E7018 equivalent and D4313 as E6013. That match is not certain, so check the packet or the maker's table. The app lists AWS names only.
Worked example: 6 mm SS400 plate
6 mm is 0.236". The stepper next to the Thickness slider moves in 0.005" steps, so set 0.235", which the readout shows as 6.0 mm. The numbers below are for that.
| Process | Settings |
|---|---|
| Stick, E7018 5/32" | 130 – 210 A, AC or DCEP, all positions; suggested rod 5/32" |
| MIG, .035 wire, 90Ar/10CO₂ | 212 – 258 A, 24.8 – 26.3 V, 338.4 – 413.6 ipm, Spray |
| MIG, .035 wire, C25 | 212 – 258 A, 19.0 – 21.0 V, short-circuit, with a spray warning |
On the Stick screen under Rod Class, pick E7018, Diameter 5/32", Thickness 0.235". Suggested Ø says 5/32", so no warning. Stick and flux core are Pro; MIG is free.
Preheat: this is where SS400 is different
SS400 specifies only phosphorus and sulphur, not carbon, so two lots can differ. The Preheat / CE screen calculates the carbon equivalent from the chemistry on your mill certificate: type carbon, manganese and the rest under Composition (weight %). The A36 Mild Steel preset gives 0.385, and the app says no preheat is needed below 0.40. If your certificate gives higher carbon, the answer changes.
This is a screening estimate in the app, not a code requirement.
What the app cannot do for SS400
It does not know JIS rod codes and it does not read a mill certificate. The thickness controls work in inches with the millimetre value beside them, so 6 mm must be converted by hand. On a job to a Japanese standard the WPS decides, not this phone.
Questions and answers
What welding electrode for SS400?
Is SS400 stainless steel?
What is the ASTM equivalent of SS400?
Does SS400 need preheat?
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