# X2NiCoMo18-9-5 Open-Die Forgings (1.6358 / Maraging 300) Source: https://www.steelforgepieces.com/Nickel-Alloy/X2NiCoMo18-9-5.html Supplier: Jiangyin Jiangnan Metal Co., Ltd., open-die forging factory Address: No.1 Chengxiqiao Road, Zhouzhuang Town, Jiangyin City, Jiangsu Province, China Telephone: +86 189 2135 9659 Email: sales@steelforgepieces.com Last updated: 1 September 2026 --- ## Summary X2NiCoMo18-9-5 is the European designation for 18% nickel maraging steel grade 300, material number 1.6358. Carbon sits below 0.03%. The strength comes from ageing at around 480 °C, which throws nickel, cobalt and molybdenum intermetallics through a martensite matrix. There is no quench anywhere in the cycle. Solution annealed and aged, the grade gives 2035 MPa (295 ksi) minimum tensile strength, 2000 MPa (290 ksi) minimum 0.2% proof strength, 12% elongation on 4D and hardness over 52 HRC. Jiangyin Jiangnan Metal Co., Ltd. forges this grade at No.1 Chengxiqiao Road, Zhouzhuang Town, Jiangyin City, Jiangsu Province, China. It is an open-die forging works, so everything is made from the customer's drawing: seamless rolled rings, shafts, flanges, discs, sleeves, bushings, tube sheets and round bars. Ultrasonic testing to EN 10228-3, SEP 1921 or ASTM A388 goes with every piece, along with an EN 10204 3.1 or 3.2 mill certificate. ## Designations | System | Designation | | --- | --- | | EN / DIN name | X2NiCoMo18-9-5 | | Werkstoff number | 1.6358 | | UNS | K93120 | | SAE / AMS | AMS 6514, bar and forgings | | ASTM | A579, A538 Grade C | | Common industry names | Maraging 300, 18Ni(300), C300, Vascomax C300, Vdimor 300, Type 300 | | Neighbouring grades | 1.6359 (X2NiCoMo18-8-5, Maraging 250), 1.6356 (Maraging 350) | ## Chemical composition, wt % | Limit | C | Ni | Co | Mo | Ti | Al | Mn | Si | Fe | | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | | Min | – | 18.00 | 8.50 | 4.60 | 0.50 | 0.05 | – | – | Bal. | | Max | 0.03 | 19.00 | 9.50 | 5.20 | 0.80 | 0.15 | 0.10 | 0.10 | Bal. | Cobalt and titanium are what separate grade 300 from grade 250, and both sit in a narrow band because they set the ageing response. With carbon under 0.03% there is no carbide hardening and no decarburised skin to cut away after heat treatment. Hardening comes from Ni3Mo, Ni3Ti and Fe2Mo precipitates instead. Phosphorus and sulphur are each held to 0.010% max. Each heat is checked on the works spectrometer before it goes to the furnace, and the analysis is printed on the certificate. ## Mechanical properties, solution annealed and aged | Property | Metric | Imperial | | --- | --- | --- | | Tensile strength, min | 2035 MPa | 295 ksi | | Yield strength, 0.2% offset, min | 2000 MPa | 290 ksi | | Elongation on 4D, min | 12 % | 12 % | | Charpy notch impact, typical | 17 J | 13 ft·lb | | Young's modulus | 195 GPa | 28.3 × 10^6 psi | | Hardness, aged | 52 HRC min | 52 HRC min | | Hardness, solution annealed | 36 HRC max | 36 HRC max | | Density | 8.0 g/cm³ | 0.289 lb/in³ | Annealed hardness runs at 36 HRC or below. That is soft enough to turn, bore, drill and weld with ordinary tooling, so most customers machine at that stage and age afterwards. Ageing is an air-cooled treatment, so the response does not fall off in heavy sections the way hardenability does in a quenched and tempered steel. A 300 mm shaft ages to much the same properties as a 50 mm one. Values cover the section sizes in AMS 6514. Guaranteed properties for a given forging thickness are fixed at order stage and confirmed on the test certificate. ## Heat treatment | Stage | Temperature | Time | Cooling | | --- | --- | --- | --- | | Hot forging | 1150 to 1200 °C start, finish above 900 °C | Soak to section | Air cool | | Solution anneal | 815 °C ± 15 °C | 1 h per 25 mm of section | Air cool | | Ageing | 480 °C ± 5 °C | 3 to 6 h | Air cool | Two stages, no quench, no preheat. That takes quench cracking off the table and removes most of the distortion, which is usually why the grade turns up on large or thin-walled forgings that would move in oil or water. Ageing runs well below the transformation temperature, so movement is small and it repeats from part to part. Take the work close to final size while it is soft, age it, then clean up. Anything that has to be cut after ageing is normally ground or spark eroded. Forgings can be shipped annealed, fully aged, or aged after the customer's own machining. ## Forged forms - Seamless rolled rings and open-die forged rings - Forging shafts: straight, stepped, hollow - Forged eccentric shafts - Forged flanges: weld neck, blind, slip on - Forged discs and disks, solid and bored - Forged round bars, rough or peeled - Forged sleeves and bushings - Hollow forged tubes and pipes - Forged tube sheets, drilled to drawing - Gear blanks and hubs - Valve bodies, blocks, stems and seat rings - Rolls, wheels and spindles Parts are forged on open dies or rolled as seamless rings, then heat treated and machined to whatever tolerance the drawing calls for. No die is cut for the job, so there is no tooling charge and a single prototype is worth quoting. ## Ordering | Item | Detail | | --- | --- | | Forging method | Open-die forging, seamless ring rolling, hollow forging | | Minimum order | One piece, no die cost, no tooling charge | | Delivery condition | As forged, rough machined, solution annealed, aged, or finish machined | | Melting route | Double melted VIM + VAR stock for AMS 6514 work, ESR refined material where the drawing allows | | Testing | Ultrasonic to EN 10228-3, SEP 1921 or ASTM A388, magnetic particle and dye penetrant on request | | Certification | EN 10204 3.1 as standard, EN 10204 3.2 with third party witness on request | Maximum diameter and forged weight depend on the section and the shape. Send the drawing or the finished dimensions for feasibility, forged weight and lead time. Cobalt makes up close to 9% of this alloy, so the price tracks the cobalt market, and quotes are held for a stated period rather than left open. ## How a forging is made 1. Material release. Ingot or billet comes in with a mill analysis. If it falls outside the 1.6358 limits it is rejected, and every heat is re-checked on the works spectrometer regardless. 2. Heating and forging. Stock is soaked and worked from about 1150 to 1200 °C, upset and drawn to break down the cast structure and put the grain flow where the part needs it. 3. Ring rolling. Rings are pierced and rolled seamless. The grain runs continuously around the circumference, which is where a rolled ring beats one cut from plate on fatigue life. 4. Solution annealing. 815 °C, air cool. What comes out is a soft martensitic matrix that machines and welds without argument. 5. Machining. Turning, boring and drilling happen here, while the metal is still soft. 6. Ageing. 480 °C for three to six hours brings the part to full strength with very little movement. 7. Inspection. Dimensions, hardness, tensile test, ultrasonic examination, then the paperwork. ## Testing and certification Every order ships with a full document set: - Ultrasonic testing to EN 10228-3, SEP 1921 or ASTM A388, at the acceptance class the drawing states - Chemical analysis of the heat, reported element by element against the 1.6358 limits - Mechanical testing for tensile, yield, elongation, reduction of area, plus Charpy impact where it is called for - Hardness in the annealed condition and again after ageing - Surface NDT by magnetic particle or dye penetrant, on request - Dimensional report against the drawing, machining allowances recorded Certificates are issued to EN 10204 3.1 as standard. Where the specification or the end client wants an independent witness, EN 10204 3.2 is arranged through SGS, BV, TÜV, Lloyd's Register or DNV. ## Applications | Industry | Forged parts | | --- | --- | | Aerospace and defence | Landing gear components, high strength shafts, motor cases, structural fittings | | Tooling and die making | Die casting dies, extrusion tooling, forging die blocks, plastic mould blocks | | Pumps and compressors | Shafts, sleeves and discs for chemical pumps, plunger pumps and air compressors | | Power transmission | Gear blanks, spindles and drive shafts for turbines, gas compressors and gearboxes | | Oil, gas and subsea | Bushings, sleeves and discs for deepwater production systems, wellhead and Christmas tree parts | | Valves | Valve stems, seat rings, blocks and bodies for ball, gate, globe, check and plug valves | | Pressure equipment | Tube sheets, flanges, forged pipes and tubes for pressure vessels and heat exchangers | | Heavy machinery | Rolls, wheels, manifolds, crankshafts and eccentric shafts for mills, mixers and marine equipment | The grade earns its place when the load is high, the envelope is tight and quench distortion is unacceptable. It is not stainless. Chromium is low, so anything working wet or in chemicals gets nitrided, plated, phosphated or painted. ## Frequently asked questions **What is X2NiCoMo18-9-5?** X2NiCoMo18-9-5 is the European (EN/DIN) name for 18% nickel maraging steel grade 300, material number 1.6358. It runs about 18% nickel, 9% cobalt and 5% molybdenum with carbon under 0.03%, and it hardens by ageing at roughly 480 °C rather than by quenching. **What is the material number for X2NiCoMo18-9-5?** 1.6358. The same steel is listed as UNS K93120, AMS 6514 for bar and forgings, and ASTM A579 or A538 Grade C. **Is X2NiCoMo18-9-5 the same as Maraging 300 or C300?** Yes. Maraging 300, 18Ni(300), C300, Vascomax C300 and Type 300 all describe the steel that EN calls X2NiCoMo18-9-5 and Germany numbers 1.6358. **What is the difference between X2NiCoMo18-9-5 and X2NiCoMo18-8-5?** Strength grade, mainly. 1.6359 (X2NiCoMo18-8-5) is maraging 250; 1.6358 (X2NiCoMo18-9-5) is maraging 300. The 300 carries more cobalt and titanium and ages to about 2035 MPa, against roughly 1725 MPa for the 250. The 250 keeps more toughness and ductility, so it is the better pick when the part has to absorb an impact rather than hold a static load. **What is the tensile strength of X2NiCoMo18-9-5?** 2035 MPa (295 ksi) minimum in the solution annealed and aged condition, with 2000 MPa (290 ksi) minimum 0.2% yield, 12% minimum elongation on 4D and hardness above 52 HRC. **How is X2NiCoMo18-9-5 heat treated?** Solution anneal at 815 °C ± 15 °C, one hour per 25 mm of section, then air cool. Age at 480 °C for three to six hours and air cool again. No quench, no preheat. Movement during ageing is small, so parts can be machined close to size beforehand. **Can X2NiCoMo18-9-5 be welded and machined?** Both, and more easily than the strength figures suggest. The work is done in the annealed condition at 36 HRC or below. With almost no carbon in the steel the weld zone does not go brittle, so preheat is normally unnecessary and the whole assembly is aged afterwards. Cutting after ageing is possible but slow, needing carbide tooling and low surface speeds; most shops grind or spark erode instead. **Is X2NiCoMo18-9-5 corrosion resistant?** No. The nickel is there for strength, not for corrosion resistance, and chromium content is low, so the steel rusts much like a carbon steel. Nitriding, plating, phosphating or paint is normal for wet or chemical service. If the part genuinely has to resist corrosion, look at a precipitation hardening stainless such as 17-4PH or PH13-8Mo. **Which forged shapes are available in X2NiCoMo18-9-5?** Seamless rolled rings, open-die forged rings, shafts and eccentric shafts, flanges, discs and disks, round bars, sleeves, bushings, hollow forged tubes and pipes, tube sheets, gear blanks, valve bodies and blocks, rolls, wheels and spindles. All to the customer's drawing. **Who supplies X2NiCoMo18-9-5 forgings?** Jiangyin Jiangnan Metal Co., Ltd. is an open-die forging factory at No.1 Chengxiqiao Road, Zhouzhuang Town, Jiangyin City, Jiangsu Province, China, supplying X2NiCoMo18-9-5 (1.6358, Maraging 300) forgings worldwide. Enquiries go to sales@steelforgepieces.com or +86 189 2135 9659. **What is the minimum order quantity?** One piece. Open-die forging cuts no die, so there is no tooling charge and a single prototype is worth quoting. **What documents come with the order?** EN 10204 3.1 as standard: heat number, chemical analysis, heat treatment record, mechanical results and hardness. The ultrasonic report to EN 10228-3, SEP 1921 or ASTM A388 and a dimensional report go with it. EN 10204 3.2 with third party witness is available on request. ## Contact Jiangyin Jiangnan Metal Co., Ltd. Open-die forging factory No.1 Chengxiqiao Road, Zhouzhuang Town, Jiangyin City, Jiangsu Province, China Telephone and WhatsApp: +86 189 2135 9659 Email: sales@steelforgepieces.com Web: https://www.steelforgepieces.com/ Send the drawing or the dimensions, the quantity, the delivery condition and any test requirements. You get back a price, a forged weight and a lead time, usually inside one working day. ## Related pages - Werkstoff 1.6358: https://www.steelforgepieces.com/Nickel-Alloy/1.6358.html - Werkstoff 1.6359, Maraging 250: https://www.steelforgepieces.com/Nickel-Alloy/1.6359.html - Werkstoff 1.6356, Maraging 350: https://www.steelforgepieces.com/Nickel-Alloy/1.6356.html - Nickel alloy forgings index: https://www.steelforgepieces.com/Nickel-Alloy/ - Seamless rolled rings: https://www.steelforgepieces.com/Forged-Rings/Forged-Ring.html - Contact: https://www.steelforgepieces.com/Contact-Us/ --- Technical data on this page is offered for guidance. The values that govern any order are those stated on the contract and the mill certificate.