Experience, innovation, commitment, and quality constitute the pillars upon which MYM Fundiciones has established itself as a leader in steel casting, in the national and international markets.
MYM Fundiciones is a steel foundry based in Lekunberri (Navarra), founded in 1998 with the mission of supplying the industry with steel parts using the shellmoulding process. It has been recognized from the beginning for the quality of the parts it produces.
A highlight in its history was the expansion in 2013, when it expanded from a 1,440 m² plant to a built area of more than 4,000 m².
MYM S.L.’s production capacity is as follows:
- Monthly Production Capacity: 50 metric tons net
- Maximum Weight per Part: 60 kg net
Number of Employees: 16
Total Area: 5,700 m²
Total Built Area: 4,000 m²
SOME OF THE STEELS WE MANUFACTURE
Alloy steels for casting are carbon steels to which alloying elements (Cr, Mo, Ni, V, W, among others) are added in order to improve specific properties such as mechanical strength, toughness, corrosion resistance, oxidation resistance, and creep resistance at high temperatures.
They are mainly used in valves, pumps, turbines, boilers, and pressure components.
There are grades designed for high temperatures (resistance to creep and oxidation) and grades for low temperatures (cryogenic toughness and impact resistance).
Example table of some alloy steels
| Designation | Type of alloy steel | Main alloying elements | Typical application |
|---|---|---|---|
| WC1 | Cr-Mo steel | 0.5% Mo, 0.5% Cr | Pressure parts, moderate temperature |
| WC6 | Cr-Mo steel | 1.25% Cr, 0.5% Mo | Valves and turbines up to ~540 °C |
| WC9 | Cr-Mo steel | 2.25% Cr, 1% Mo | Boilers, turbines, high creep resistance |
| C5 | Cr-Mo-V steel | 5% Cr, 0.5% Mo, V traces | High temperature and oxidation resistance |
| C12 | 12% Cr steel | 12% Cr, Mo | Vapor turbines, corrosion resistance |
| LC1 | Ni steel (low temperature) | ~3.5% Ni | Valves at -46 °C |
| LC2 | Ni steel (low temperature) | ~2.5% Ni | Cryogenic equipment, good toughness |
| LC3 | Ni steel (low temperature) | ~3.5% Ni | Cryogenic service down to -101 °C |
Cast austenitic stainless steels are Fe-Cr-Ni alloys (with additions of Mo, Nb, Cu, N, etc.) that have:
- They are used in valves, pumps, pressure vessels, and chemical components.
- Excellent resistance to general and localized corrosion.
- Very good toughness at low temperatures.
Sample table of some austenitic stainless steels
| Designation | Equivalent / Type | Typical composition | Typical application |
|---|---|---|---|
| 1.4308 | Austenitic (304 cast / CF8) | 18% Cr, 9% Ni | General use, valves, pumps, vessels |
| 1.4408 | Austenitic (316 cast / CF8M) | 18% Cr, 10% Ni, 2-3% Mo | Marine environments, chemicals, high corrosion |
| 1.4581 | Austenitic (cast 316Ti) | 17% Cr, 11% Ni, 2% Mo, Ti | High temperature, furnaces, turbines |
| 1.4552 | Ti-stabilized austenitic | 17% Cr, 12% Ni, Ti | Intergranular resistance, thermal service |
| 1.4468 | Special austenitic (similar to 20) | 20% Cr, 25% Ni, 4% Mo, Cu | Chemical industry and hazerdous acids |
| 1.4470 | High Cr-Ni-Mo austenitic | ~25% Cr, 20% Ni, Mo | Aggressive chlorinated environments |
| 1.4519 | Austenitic with Cu (cast 904L) | 20% Cr, 25% Ni, 4% Mo, Cu | Hazerdous acids, chemical plants |
| CF8 | Austenitic (304 cast) | 18% Cr, 9% Ni | Valves, pumps, general use |
| CF8M | Austenitic (316 cast) | 18% Cr, 11% Ni, 2% Mo | Chemical and marine industry |
| CF8C | Stabilized austenitic Nb | 18% Cr, 9% Ni, Nb | High temperature, creep resistance |
| CF3 | Austenitic (cast 304L) | Low C, 18% Cr, 9% Ni | Resistance to intergranular corrosion |
| CF3M | Austenitic (cast 316L) | Low C, 18% Cr, 11% Ni, 2% Mo | Chemical services |
| CN7M | High Ni-Cu-Mo Austenitic (Alloy20) | 20% Cr, 35% Ni, 3% Mo, Cu | Sulfuric acid industry |
| CN3M | Austenitic Ni-Cr-Mo (Hastelloy C) | 22% Cr, 65% Ni, 17% Mo | Heavy chemicals and aggressive chlorides |
Note on duplex and super duplex
Although they are not austenitic, in many casting catalogs they are presented with them:
| Designation | Type of stainless steel | Typical composition | Typical application |
|---|---|---|---|
| Duplex | Balanced Fe-Cr-Ni-Mo-N | ~22% Cr, 5% Ni, 3% Mo, N | Offshore, chemical plants, paper |
| Superduplex | High-performance Fe-Cr-Ni-Mo-N | 25% Cr, 7% Ni, 4% Mo, N | Seawater, oil, gas, salt flats |
Cast martensitic stainless steels are Fe-Cr alloys (with controlled C, sometimes Ni and Mo) that are hardened by heat treatment (quenching and tempering).
Key features:
- They are used in structural components, hydraulic turbines, valves, pumps, and parts subject to erosion/abrasion.
- Greater mechanical strength and resistance wear than austenitic steels.
- Less toughness and corrosion resistance than austenitic and duplex steels.
Sample table of some martensitic steels
| Designation | Equivalent / Type | Typical composition | Typical application |
|---|---|---|---|
| CA15 | Martensitic stainless steel (410) | 12% Cr, 0.15% C | Turbines, pumps, valves, good resistance |
| CA6NM | Martensitic stainless steel (13Cr-4Ni) | 13% Cr, 4% Ni, Mo | Hydraulic turbines, compressors, cryogenic |
| 1.4008 | Martensitic stainless steel(410) | 12% Cr, 0.12% C | Valves, pumps, structural parts |
Hastelloy alloys are nickel-chromium-molybdenum (Ni-Cr-Mo) superalloys, with variants that include W, Fe, or Co. They are known for:
- Used in the chemical and petrochemical industries, acid plants, offshore equipment, and high-performance components in highly aggressive conditions.
- Excellent corrosion resistance in oxidizing and reducing environments.
- High performance in strong acids (hydrochloric, sulfuric, phosphoric).
Example table (Hastelloy castings and related materials)
| Designation | Type / Equivalent | Typical composition (approx.) | Typical application |
|---|---|---|---|
| CW12MW | Hastelloy C (Ni-Cr-Mo-W) | 65% Ni, 16% Cr, 16% Mo, 4% W | Hazerdous acids, aggressive chemical equipment |
| CW6MC | Hastelloy C-276 (Ni-Cr-Mo-W) | 57% Ni, 16% Cr, 16% Mo, 4% W, Fe | Chemical plants, chlorides, oxidants |
| 2.4883 | Ni-Cr-Mo alloy (Hastelloy X) | 47% Ni, 22% Cr, 9% Mo, Fe, Co | Furnaces, turbines, oxidation resistance |
| 2.4697 | Ni-Mo alloy (Hastelloy B) | 65% Ni, 28% Mo, 1% Fe | Resistance to hydrochloric acid |
Tool steels and tempered and annealed alloy steels (such as GS42CrMo4) are used in casting when the following are required:
- High mechanical properties (strength, toughness, and high yield strength).
- Good wear and fatigue resistance.
- Can be heat treated (hardening, tempering, nitriding).
They are used in molds, dies, gears, shafts, structural parts subjected to high stresses, and heavy machinery components.
Example table (tool steels/alloy steels tempered and annealed in casting)
| Designation | Type of cast steel | Typical composition (approx.) | Typical application |
|---|---|---|---|
| GS42CrMo4 | Tempered and annealed alloy steel | 0.42% C, 1% Cr, 0.25% Mo | Axles, gears, machine parts |
| GS34CrNiMo6 | High-strength alloy steel | 0.34% C, 1.5% Cr, 1.5% Ni, 0.25% Mo | Crankshafts, critical components |
| GS55CrSiMo5 | Tool steel | 0.55% C, Cr, Si, Mo | Molds, forging dies, blades |
| GS90MnCrV8 | Cr-V tool steel | 0.90% C, 2% Mn, 0.5% Cr, V | Dies, punches, cutting tools |
All internationally recognized specifications apply. Mainly DIN and ASTM, ASME, BS, EN, SEW, JIS, RCC-M, etc., which are subject to periodic review and updating.
Steel foundry with international scope
The commitment to quality, the certification of our quality management systems, the commitment to respect the environment, the facilities, the precision in delivery times, and the competitiveness in costs have allowed more than 75% of our production to be destined for international end customers.
The high level of quality has allowed the company to obtain ISO 15085 CL1 certification, which has increased its presence in the railway sector.
Quality and respect for the environment
The company has a robust quality management system in place, compliant with ISO 9001, geared towards the production of cast steel parts in various compositions. This system is supported by state-of-the-art facilities and specialized laboratories.
To satisfy its customers’ needs, the company collaborates with leading auxiliary companies, offering additional services for cast parts, such as machining and special heat treatments..
In addition to cast steel, MYM Fundiciones produces centrifugal castings, always with a sustainable approach.
In the interests of respecting the environment, MYM Fundiciones installed a photovoltaic system which, as of August 2025, has achieved a significant reduction in emissions.
