X11CrMo5 (1.7362) Forgings: Rings, Flanges, Bars and Discs

5Cr-0.5Mo creep-resistant alloy steel · EN 10222-2 and ASTM A182 F5 · Open-die forged in Jiangyin, China

X11CrMo5, EN material number 1.7362, is a creep-resistant low-alloy steel with 4.00 to 6.00 % chromium and 0.45 to 0.65 % molybdenum. It is used for pressure-retaining parts working at elevated temperature, normally up to about 600 °C, in refineries, boilers, heat exchangers and petrochemical plant. The nearest ASTM counterparts are A182 F5 for forgings, A335 P5 for pipe and A387 Grade 5 for plate. Jiangyin Jiangnan Metal Co., Ltd. forges the grade at its open-die plant in Jiangyin, Jiangsu, China, in seamless rolled rings to 4,500 mm outside diameter and single pieces to 20 tonnes, with EN 10204 3.1 or 3.2 certification.

What X11CrMo5 is

X11CrMo5 belongs to the chromium-molybdenum family developed for pressure equipment that runs hotter than plain carbon steel can take. Chromium gives oxidation resistance and, in refinery service, resistance to sulfidic corrosion. Molybdenum raises creep rupture strength by keeping carbides stable at temperature. At around 5 % chromium the grade sits between the 2¼Cr-1Mo steels (10CrMo9-10, A182 F22) and the 9 % chromium steels (X11CrMo9-1, A182 F9).

The grade runs through the whole EN pressure family: EN 10222-2 for forgings, EN 10216-2 for seamless tube, EN 10253-2 for butt-welding fittings and EN 10028-2 for flat product. Open-die forgings, ring-rolled products and forged bar for pressure purposes also follow the general rules in EN 10222-1.

One property matters more than the rest when you buy the grade forged. X11CrMo5 is air hardening. A heavy section left to cool in still air will form martensite, so cooling after forging has to be controlled and tempering is not optional. Most of the cracked and out-of-spec 5Cr forgings that come back for investigation got there because a furnace cycle was skipped. It is a good reason to buy from a forge that heat treats on site rather than one that sends the work out.

X11CrMo5 designations and international equivalents

The same 5Cr-0.5Mo chemistry turns up under a lot of names, depending on country, standard and product form. The table maps the ones we are asked for most often.

Cross-references are nominal. EN and ASTM grades differ in permitted element ranges, testing, tolerances and delivery condition, so a certificate to one standard does not automatically satisfy another. Where dual certification is wanted, put both standards on the purchase order and the forging is produced to the tighter of the two.

X11CrMo5 chemical composition

The limits below are from EN 10253-2 for X11CrMo5 (1.7362). EN 10216-2 and EN 10222-2 carry the same ranges for the principal elements. Figures are percentage by mass, balance iron.

Product analysis tolerances apply per the governing standard. Both heat analysis and, on request, product analysis are reported on the EN 10204 3.1 certificate.

X11CrMo5 mechanical properties

Required properties follow the governing standard and the delivery condition, not the grade on its own. The rows quoted most often for 5Cr-0.5Mo are set out separately below, because pipe values under ASTM A335 P5 sit well under forging values under ASTM A182 F5 and the two get mixed up constantly.

Requirements usually added for forgings: reduction of area 35 % min, hardness 217 HBW max for ASTM A182 F5, and Charpy V-notch impact testing where the purchaser calls for it. EN 10222-2 tabulates properties by governing thickness, so a 600 mm tubesheet is not held to the same minima as a 60 mm ring. The +NT2 row is left without figures on purpose. It is the higher-strength class of EN 10216-2 Table 4, and we do not publish a number we cannot tie to the current edition of the standard. Order values are confirmed on the material test certificate.

Elevated-temperature behaviour

Allowable stress falls away above roughly 400 °C as creep takes over as the governing mechanism. Creep rupture data for X11CrMo5 sits in the informative annexes of the EN 10222 and EN 10216 series, and ASME BPVC Section II Part D tabulates allowable stress for the equivalent F5 and P5 materials. The grade is also chosen for where it sits on the Nelson curve, which is what gives it resistance to high-temperature hydrogen attack in hydroprocessing service.

X11CrMo5 physical properties

Physical properties are typical values for the 5Cr-0.5Mo family, given for design guidance. They are not certified values and are not guaranteed by the material standards.

Heat treatment of X11CrMo5

EN 10216-2 sets three standard delivery conditions for X11CrMo5, and the same cycles apply to forgings with soak times adjusted for section. Tempering temperature is what separates +NT1 from +NT2: the lower range used for +NT2 leaves more strength in the part.

For wall thickness above 25 mm, or where T/D goes over 0.15, EN 10216-2 notes that quenching and tempering may be needed to get the intended structure through section. Heavy open-die forgings are therefore routinely supplied +QT rather than +NT. Soak time is set from the governing thickness, and a furnace chart goes out with every batch.

Forging practice for X11CrMo5

These are the shop settings we run for X11CrMo5. They are production figures, not a reprint of a standard.

Welding and post-weld heat treatment

X11CrMo5 welds well enough with a qualified procedure, but it punishes shortcuts. It air hardens, so the heat-affected zone forms hard martensite as the joint cools unless the controls below are in place.

Do not let a 5Cr weldment cool to ambient before PWHT unless the procedure allows an intermediate dehydrogenation hold. The figures above are indicative. The qualified WPS and PQR govern.

Machinability of X11CrMo5

Machinability is best in the isothermally annealed condition, which is why heavy forgings are normally rough machined annealed, heat treated to the final condition, then finish machined. Once normalised and tempered, the 5 % chromium makes the material hard on tooling. Use rigid setups, positive-rake carbide, lower cutting speed than plain carbon steel and plenty of coolant. Leave stock for the movement that comes with quality heat treatment of a large ring or tubesheet, usually 3 to 8 mm per side depending on diameter and wall.

Where X11CrMo5 is used

X11CrMo5 gets specified where temperature, hydrogen partial pressure and sulfur-bearing hydrocarbons rule out carbon and low-chrome steels, but the cost of 9Cr or stainless is not justified.

X11CrMo5 forged products we supply

Everything below is made in house at our open-die plant in Jiangyin, to customer drawing or to standard dimensions.

Machining condition is your choice: as forged with envelope allowance, rough machined, or finish machined to drawing tolerance. Clad and weld-overlay surfaces in 309L/347, Inconel 625 and Incoloy 825 are available on tubesheets and channel covers.

Factory capability

The figures below describe the plant that makes these parts, so you can size a job against real capability before sending an enquiry.

Check current capacity against your drawing. Soaking pit dimensions and quench tank size, not press tonnage, are usually what decides whether a part can be made in one piece.

Testing, inspection and certification

Every X11CrMo5 forging leaves the plant with traceability from heat number to finished piece. The standard documentation package covers:

• Heat analysis and, on request, product analysis by optical emission spectrometry
• Tensile test at room temperature, elevated-temperature tensile on request
• Charpy V-notch impact testing at the specified temperature where required
• Brinell hardness survey
• Ultrasonic examination to EN 10228-3, ASTM A388 or SEP 1921, to the acceptance class ordered
• Magnetic particle or liquid penetrant examination of machined surfaces
• Micrographic examination and grain size where specified
• Heat-treatment furnace charts with thermocouple placement record
• Dimensional report against the approved drawing
• EN 10204 type 3.1 certificate, or type 3.2 with third-party endorsement

Positive material identification at final inspection, hardness mapping, HIC and SSC testing to NACE MR0175 and ISO 15156 where the service calls for it, and NORSOK or client-specific supplementary requirements can all be added to the inspection and test plan.

Frequently asked questions about X11CrMo5