Which grade of stainless steel

I'm just about to make a grate for a 3.5 gauge locomotive out of stainless steel and was wondering if there was a recommended preference which grade of stainless to use.

I understand the machinability of the different grades and that some are more resistant to the corrosive gases than others so what would be the best all rounder.

Joe

I would use 316 ! BUT when drilling or working it any tool MUST cut ! if it rubs it will almost instantly harden and your in trouble as it will be so hard ordinary drills won't touch it. But it welds nicely. Good luck, Noel

Hi Joe,

More ino on heat resistance of stainless steel here.

Thor

Basic types a firm where I worked was 304 for general purpose, 316 for Hygenic applications or 321 for heat applications. Yes there are Inconels and Nimonics for ultimate heat but we are talking toy trains, not F1.

Regards Ian.

Edited By Circlip on 26/06/2021 08:54:43

At work, many years ago after some problems machining 316 plate and ruining a couple of cutters, I made some inquiries of the metal supplier. It seems that, at least up here in Australia 316 plate is intended for weldments and fabrications where little or no machining is anticipated, 316 bar has a dollop of sulphur included which makes it very machineable, but not very weldable. I don't know if this practice is followed wherever Joe McKean is, but it might stand some further investigation!!

Best of luck

cheers

Bill

303 stainless has Sulphur in (0.15-0.35%), 316 has 0.03% max Sulphur content.

Jim

And easier machineability was noted by 304L and 316L for lower Carbon content.

Regards Ian.

303 Stainless is free machining version of 304. 304 is great for cryogenics, BOC used to make its cryogenic plants with 304 SS.

316 is better for Salt water corrosion, 321 for heat.

Peter

For the OP's firegrate, any 300 series austenitic steel will vastly out-perform mild steel or cast iron, and probably last the proverbial lifetime.

Since it's readily available, I'd probably use 304(L) sheet for the firebars.