What heavy gauge plate is actually used for
A 150 mm stainless plate is not a bigger version of a 3 mm sheet. At that thickness the material is bought for a specific job: furnace and kiln structure, heat treatment fixtures, large valve bodies, pump housings, die blocks, roll shells, or a machined component where the plate is the raw stock rather than the finished part. The buying decision is driven by heat resistance or by the amount of machining allowance, not by surface finish.
Because the weight per piece is high, freight and handling usually decide the supply shape. A single 150 mm plate at 1500 x 3000 mm weighs about 5.3 tonnes. Buyers therefore tend to ask for the plate cut to the blank size at our works rather than shipping a full plate and cutting at destination.
Grade selection for heat and for cost
310S (25 percent chromium, 20 percent nickel) is the grade for continuous service around 1000 to 1100 C: furnace retorts, radiant tubes, kiln internals, annealing fixtures. It forms a tight oxide scale that stays in place, which is what gives it the oxidation resistance. It is austenitic, weldable, and non-magnetic in the annealed condition.
321 (titanium stabilised) covers the 425 to 815 C band where 304 would sensitise and suffer intergranular corrosion. Exhaust manifolds, expansion joints, boiler plate and heat exchanger shells are typical. Above 815 C the titanium carbide starts to dissolve and the advantage is lost, so 321 is not a substitute for 310S at higher temperature.
430 (16 to 18 percent chromium, ferritic, no nickel) is the cost driven choice for non-structural heat and mild corrosion duty: appliance backs, burner parts, heat shields, decorative trim. It is magnetic, less formable than the austenitic grades, and it becomes brittle if held in the 400 to 500 C range for long periods, which is a real limitation in furnace service.
201 is used where the part is indoors, dry and cost sensitive: frames, supports, bases and general fabrication.
Dimensions and cut capability
| Parameter |
Value |
| Thickness |
3 - 150 mm |
| Width |
1000 / 1500 / 2000 mm |
| Length |
up to 6000 mm |
| Grades |
321, 310S, 201, 430, 304, 316L on request |
| Surface |
No.1 hot rolled and pickled |
| Cutting |
Plasma to 60 mm, waterjet to 150 mm, saw cut on request |
| Standard |
ASTM A240 / A480, EN 10028-7 |
| Test |
EN 10204 3.1, UT and PMI on request |
Thickness tolerance at 150 mm follows ASTM A480 or EN 10029 class A, which allows a wider band than sheet tolerance. If the plate is a machining blank, quote the finished dimension and add the allowance; we will confirm the as supplied thickness range in the offer so the machining plan is not built on an assumption.
Cutting and machining notes
- Waterjet leaves a square edge with no heat affected zone, which matters on 310S because thermal cutting creates a chromium depleted layer that must be ground off before high temperature service.
- Plasma cut edges on thick austenitic plate need grinding back 1 to 2 mm before welding; the nitride layer on the cut face causes porosity.
- Drilling 310S and 321 at 100 mm plus needs cobalt tooling, low speed and continuous coolant. Work hardening is the main risk, not hardness.
- Stress relief after heavy machining is not normally required for 321 or 310S, but it is for 430 if the part must hold dimensional stability in service.
Inspection for heavy plate
Heavy plate is normally inspected more thoroughly than sheet because the cost of a reject at the machine shop is high. We supply the EN 10204 3.1 certificate as standard, and can add ultrasonic testing to EN 10160 class S1/E1 or ASTM A578 level II, positive material identification by XRF on each piece, and dimensional inspection reports against the purchase drawing. BV or TUV third party inspection is available where the end user's specification demands it.
Frequently asked questions
Can you cut a 150 mm plate to a complex profile?
Yes, by waterjet, with a typical tolerance of plus or minus 1 mm on thickness above 100 mm. Fine features below 10 mm are better machined than cut.
Is 310S available in 150 mm?
310S is normally rolled to 60 to 80 mm. Above that we quote forged block or 310S slab, with a longer lead time.
What is the lead time for heavy plate?
Stock sizes ship in 7 to 10 days. Non stock thicknesses are 25 to 40 days depending on the mill rolling schedule.
Do you supply test bars with the plate?
Yes, on request the mill can leave a prolongation on the plate for the buyer's own mechanical testing.
Your message must be between 20-3,000 characters!
