20MnMoNi55 Steel Plate Applications & Ordering Guide

20MnMoNi55 / 20MnMoNi5-5 (DIN 1.6310; SEW pressure-vessel QT steel) is specified for industrial fabrications where the drawing or material list names this grade. This applications page explains where the grade is used, what service conditions drive selection, and which certificate details belong on the purchase order. Gangsteel supplies 20MnMoNi55 / 20MnMoNi5-5 (DIN 1.6310; SEW pressure-vessel QT steel) with EN 10204 mill test certificates.

Typical Applications and Service Conditions

20MnMoNi55 / 20MnMoNi5-5 (DIN 1.6310; SEW pressure-vessel QT steel) plate is ordered for pressure equipment, process vessels, heat-exchanger related fabrications, structural members under the governing code, and project packages that call the grade by name. Match the mill test certificate grade mark to the calculation sheet; do not treat near-equivalents as automatic substitutes.

Service drivers include the design temperature and pressure of the governing code (ASME, EN/PED, class society, or project specification), weld procedure qualification needs, toughness or creep allowables where applicable, and inspection scope. Delivery condition Quenched and tempered (austenitize ~870-930 C, temper ~630-690 C typical) should be stated explicitly on the purchase order.

Industry Use Cases

Pressure equipment and process: shells, heads, and related platework when drawings name 20MnMoNi55 / 20MnMoNi5-5 (DIN 1.6310; SEW pressure-vessel QT steel). Power and energy: boiler and heat-recovery fabrications under the ordered edition. Marine / offshore (when classed): only when the society material list names this exact grade stamp. Always keep heat-number traceability on cut pieces.

Chemical Composition - Supporting Data (20MnMoNi55 / 20MnMoNi5-5 (DIN 1.6310; SEW pressure-vessel QT steel))

Heat analysis for DIN 20MnMoNi5-5 / SEW 20MnMoNi55. Wuyang WYJ036 mill route may use slightly different C/Mn bands - prefer the ordered tech condition on the MTC.

Element / rule	Requirement
C	0.17-0.23
Si	0.15-0.30
Mn	1.20-1.50
Ni	0.50-0.80
Mo	0.40-0.55
Al	0.010-0.040
V, max	0.03
Cr, max	0.20
Cu, max	0.12-0.18 (edition-dependent)
P, max	0.025
S, max	0.010

Mechanical Properties - Supporting Data (20MnMoNi55 / 20MnMoNi5-5 (DIN 1.6310; SEW pressure-vessel QT steel))

Confirm thickness, specimen orientation, and any supplementary impact, UT, or hardness requirements on the PO.

Property	Requirement
Tensile Rm	560-730 MPa
Yield Rp0.2, min	390 MPa
Elongation A, min	16%
Delivery / HT	Q+T; stress-relief often 580-620 C

Related / Near-Equivalent Grades

Near-equivalents are for cross-reference only. They are not automatic code substitutes. Substitution requires engineer approval and matching certificate scope.

System	Grade	Note
ASTM/ASME	A508 Gr.3 Cl.1 / SA-508 Class 3	Implicit near-equivalent - confirm
ASTM	A533 Type B Class 1 family	Mn-Mo-Ni PV family
DIN	1.6310	Material number

Frequently Asked Questions

Where is 20MnMoNi55 / 20MnMoNi5-5 (DIN 1.6310; SEW pressure-vessel QT steel) typically applied?

20MnMoNi55 / 20MnMoNi5-5 (DIN 1.6310; SEW pressure-vessel QT steel) is applied where design documents, class material lists, or purchaser specs name this grade for pressure, process, structural, or marine fabrications as applicable. Match the MTC marking to the drawing.

What service conditions drive selection of 20MnMoNi55 / 20MnMoNi5-5 (DIN 1.6310; SEW pressure-vessel QT steel)?

Design temperature and pressure, toughness or creep allowables, weldability, corrosion or process media, and the governing code edition drive selection. Delivery condition Quenched and tempered (austenitize ~870-930 C, temper ~630-690 C typical) must align with the ordered specification.

Can a near-equivalent replace 20MnMoNi55 / 20MnMoNi5-5 (DIN 1.6310; SEW pressure-vessel QT steel) on an applications drawing?

Not without redesign and written approval. Near-equivalents differ in chemistry, heat treatment, impact temperature, or product form. Commercial swaps create non-conformance when the dossier names 20MnMoNi55 / 20MnMoNi5-5 (DIN 1.6310; SEW pressure-vessel QT steel).

What fabrication notes matter for 20MnMoNi55 / 20MnMoNi5-5 (DIN 1.6310; SEW pressure-vessel QT steel)?

Use approved WPS/PQR packages for the thickness and filler, control heat input, and preserve heat-number traceability on cut pieces. State any supplementary UT, PMI, or impact tests on the purchase order.

What certificate and marking should an applications PO demand?

EN 10204 3.1 is standard; 3.2 when a purchaser-appointed inspector witnesses tests. The MTC should show heat analysis, tensile results, delivery condition, and heat number aligned with 20MnMoNi55 / 20MnMoNi5-5 (DIN 1.6310; SEW pressure-vessel QT steel).

How should I RFQ 20MnMoNi55 / 20MnMoNi5-5 (DIN 1.6310; SEW pressure-vessel QT steel) plate from Gangsteel for a project?

Send 20MnMoNi55 / 20MnMoNi5-5 (DIN 1.6310; SEW pressure-vessel QT steel), thickness x width x length (or nesting list), quantity, delivery condition, optional NDT/PMI, certificate type, destination, and any dual-mark needs. Note the end use when special flatness or cut-to-size packaging is required.

Ordering and Mill Certificates

State grade 20MnMoNi55 / 20MnMoNi5-5 (DIN 1.6310; SEW pressure-vessel QT steel), dimensions, quantity, delivery condition, optional NDT/PMI, and certificate (EN 10204 3.1 standard; 3.2 when third-party inspection is ordered). Gangsteel supplies export plate and related products with mill test certificates. Contact Gangsteel for stock and mill production RFQs.