18NiCrMo5: Steel Technical Specifications

0118NiCrMo5 Steel: Introduction and General Characteristics

18NiCrMo5 steel, now designated 17NiCrMo6-4 under the new standard, is one of the most significant alloys among case-hardening steels, engineered specifically for industrial applications requiring high mechanical performance and wear resistance. This ferrous alloy, characterised by the presence of nickel, chromium and molybdenum, represents a well-established technical solution for components subjected to dynamic stresses and heavy loads.

18NiCrMo5 is classified according to the UNI 7846:1978 standard (historical standard) as an alloyed case-hardening steel, equivalent to the European designation 17NiCrMo6-4 (1.6566) and to the SAE/AISI 4317 classification. For up-to-date standard specifications, refer to EN ISO 683-3:2022 (formerly EN 10084), case-hardening steels - technical delivery conditions. This international standardisation ensures uniformity in the technical specifications and facilitates identification of the material across different global industrial contexts. The alphanumeric designation reflects the chemical composition of the steel, where the prefix "18" indicates the average carbon content (0.18%), while the symbols Ni, Cr and Mo identify the characterising alloying elements.

The properties of 18NiCrMo5 stem from the synergistic combination of alloying elements that give the material superior mechanical characteristics compared with conventional carbon steels. Nickel (1.2-1.5%) contributes to toughness and impact resistance, chromium (0.7-1.0%) improves hardenability and corrosion resistance, while molybdenum (0.15-0.25%) increases mechanical strength at high temperatures and dimensional stability. Through suitable heat treatments, this combination makes it possible to achieve a surface hardness of 58-62 HRC while maintaining toughness in the core.

1.118NiCrMo5 vs Conventional Steels: Differences

The differences between 18NiCrMo5 and conventional steels are evident mainly in its superior response to heat treatment and in its mechanical performance after case hardening. Compared with plain carbon steels such as C45, 18NiCrMo5 exhibits significantly higher hardenability, allowing high hardness values to be achieved even in thicker sections. The presence of alloying elements provides resistance to temper embrittlement, a phenomenon typical of non-alloy steels that limits their applicability under severe operating conditions.

Compared with simpler case-hardening steels such as 16MnCr5, 18NiCrMo5 offers superior performance in terms of fatigue strength (a 40-60% increase) and dimensional stability during heat treatment. The molybdenum content prevents austenitic grain growth during case hardening, maintaining uniform mechanical properties even during the prolonged thermal cycles required to achieve high case-hardening depths.

1.218NiCrMo5 Advantages for Industrial Applications

The advantages of 18NiCrMo5 in industrial applications include its application versatility, ranging from the automotive sector to heavy engineering, with particular reference to critical components such as gears, camshafts, half-shafts and bearings. Its ability to maintain high mechanical performance under demanding operating conditions makes it ideal for applications where operational reliability is a non-negotiable parameter.

The excellent machinability of 18NiCrMo5 in the annealed condition (200-225 HB) facilitates turning, milling and drilling operations, reducing machining times and tool wear compared with harder steels. This characteristic translates into significant economic benefits for the production of series components, where optimisation of production processes directly affects the competitiveness of the finished product.

1.318NiCrMo5 Standards and Certifications

The standards for 18NiCrMo5 follow well-established international standards that ensure the quality and traceability of the material. The Italian standard UNI 7846:1978 (historical standard) defines chemical composition, mechanical properties and test methods, while the corresponding European standard EN ISO 683-3:2022 (formerly EN 10084) sets the requirements for conformity certification. The designation 17NiCrMo6-4 (material number 1.6566) according to EN 10027-2 facilitates unambiguous identification of the material in international markets.

The quality certifications for 18NiCrMo5 provide for certificates in accordance with EN 10204, type 2.1 (manufacturer's certificate of compliance) or 3.1 (specific inspection certificate) for critical applications. Each heat is accompanied by a certified chemical analysis, mechanical tests on representative samples and metallographic inspections to verify the microstructure and the purity index in accordance with ISO 4967.

02Chemical Composition of 18NiCrMo5 Steel: Alloying Elements and Standard Specifications

The chemical composition of 18NiCrMo5 is the foundation of its exceptional mechanical properties and is precisely defined by the UNI 7846:1978 standard. This complex alloy combines a base of iron with specific elements that give the material the hardenability, toughness and mechanical strength characteristics required for the most demanding applications in the mechanical engineering sector.

The chemical specification of 18NiCrMo5 according to the Italian standard UNI 7846:1978 establishes strict parameters for each constituent element. The carbon content is between 0.15-0.21%, ensuring the right balance between hardness and toughness after case hardening. Silicon (0.15-0.40%) acts as a deoxidizer during production and contributes to mechanical strength, while manganese (0.60-0.90%) improves hardenability and neutralizes the harmful effects of sulphur. The residual elements phosphorus and sulphur are each limited to a maximum of 0.035% to prevent intergranular embrittlement and ensure the machinability of the material.

The characterising alloying elements of 18NiCrMo5 include chromium (0.70-1.00% under the historical standard UNI 7846:1978 and 0.80-1.10% for 17NiCrMo6-4, EN ISO 683-3:2022 (formerly EN 10084)), molybdenum (0.15-0.25%) and nickel (1.20-1.50%). Chromium increases hardness and corrosion resistance, forming stable carbides during heat treatments. Molybdenum is essential for mechanical strength at high temperatures and prevents temper embrittlement, while nickel provides exceptional toughness and improves impact resistance at low temperatures. This synergistic combination makes it possible to achieve the properties of 18NiCrMo5 that make it superior to conventional carbon steels.

2.118NiCrMo5 International Equivalents

The international equivalents of 18NiCrMo5 facilitate procurement and substitution of the material in multinational projects. The corresponding European designation 17NiCrMo6-4 (EN 1.6566) shows slight variations in the chemical composition of 18NiCrMo5, with carbon at 0.14-0.20% and slightly different ranges for the other elements. The American SAE/AISI 4317 classification and the British BS 815M17 maintain substantial equivalence in the final mechanical performance.

Some commercial variants include controlled additions of lead (0.15-0.35%) to improve machinability, or controlled sulphur (0.020-0.035%) to facilitate turning and milling operations. These modifications do not significantly alter the mechanical characteristics of the material but optimise production processes for specific applications where machining speed is a critical parameter.

03Mechanical Characteristics of 18NiCrMo5 Steel: Properties and Structural Performance

The mechanical characteristics of 18NiCrMo5 are the result of the synergistic interaction between chemical composition and heat treatments, giving this case-hardening steel superior performance for critical structural applications. A detailed understanding of the mechanical properties of 18NiCrMo5 is essential for the correct design and selection of the material in industrial settings.

3.1Mechanical Properties of 18NiCrMo5 in the Annealed Condition

The mechanical properties of 18NiCrMo5 in the annealed condition represent the characteristics of the material in its state of maximum machinability, obtained through full annealing at 850 °C followed by slow cooling in the furnace. In this metallurgical state, the structure consists of ferrite and lamellar pearlite, with a Brinell hardness of 200-225 HB according to the UNI 7846:1978 standard.

The tensile strength in the annealed condition is 600-650 MPa with a yield strength of 400-450 MPa, ensuring good formability for cold-forming operations. The percentage elongation reaches values of 12-15%, while the reduction of area exceeds 35%, indicating excellent ductility for complex machining operations. These parameters make 18NiCrMo5 ideal for components that require turning and milling operations before the final heat treatment.

3.2Mechanical Strength of 18NiCrMo5 in the Quenched and Tempered Condition

The mechanical strength of 18NiCrMo5 in the quenched and tempered condition varies significantly depending on the delivery conditions and the heat-treatment parameters applied. Quenching and tempering, consisting of hardening followed by tempering, makes it possible to optimise the strength-to-toughness ratio for various structural applications.

In the quenched and tempered condition, the tensile strength (Rm) ranges from 785-1520 MPa, with values decreasing as the thickness of the part increases. For sections up to 11 mm, the UNI 7846:1978 standard specifies a strength of 1225-1520 MPa with a minimum yield strength (Re) of 980 MPa. Thicker sections (40-100 mm) show strength values of 785-1080 MPa with a minimum Re of 590 MPa.

3.318NiCrMo5 Hardness After Case Hardening

The hardness of 18NiCrMo5 after case hardening is the most critical performance parameter for evaluating the effectiveness of the heat treatment and its compliance with application specifications. The hardness profile obtained through controlled case hardening defines the tribological performance of the component and its wear resistance under severe operating conditions.

The surface hardness of 18NiCrMo5 reaches exceptional values of 58-62 HRC according to the UNI 7846:1978 standard, with optimal peaks of 62 HRC for automotive and precision-engineering applications. These values result from the martensitic transformation of the carbon-enriched layer (0.8-1.2% surface C) obtained through gas carburizing at 920-930 °C. The case-hardening depth, measured as the distance from the surface to the point with a hardness of 50 HRC, typically ranges from 0.8-2.0 mm depending on the process time and the geometry of the component.

The hardness gradient of 18NiCrMo5 exhibits a characteristic gradual transition from the case-hardened surface to the base core. At 0.5 mm from the surface, values of 55-58 HRC are recorded, while at 1.0 mm the hardness drops to 45-50 HRC. The core maintains a hardness of 30-40 HRC, providing the structural toughness needed to absorb dynamic loads and impacts.

3.4Impact Strength and Toughness of 18NiCrMo5

The deformability properties of 18NiCrMo5 show optimal behaviour for dynamic applications. The percentage elongation (A%) ranges between 8-10% depending on thickness, with higher values for larger sections reaching 10%. The reduction of area (Z%) exceeds 30% under optimal conditions, indicating excellent plastic deformation capacity before fracture.

The impact toughness of 18NiCrMo5, measured on Charpy U-notch (KCU) specimens, is typically 30-35 J depending on section size. These parameters indicate the material's ability to absorb impact energy without brittle failure, a fundamental characteristic for components subjected to severe dynamic stresses such as gears and transmission shafts.

3.5Fatigue and Dynamic Behaviour of 18NiCrMo5

The fatigue behaviour of 18NiCrMo5 represents one of the most significant aspects for automotive and industrial mechanical applications. High-cycle fatigue strength, determined according to the ISO 1143 standard, shows fatigue limits 300-400% higher than those of the material not heat-treated.

The martensitic structure of the case-hardened surface, combined with the toughness of the ferritic-pearlitic core, gives the component excellent resistance to fatigue crack propagation. The compressive residual stresses generated by case hardening further contribute to increasing fatigue life, which is particularly significant for high-speed rotating components where cyclic stresses represent the most probable failure mode.

04Physical Characteristics of 18NiCrMo5 Steel: Thermal and Structural Properties

The physical characteristics of 18NiCrMo5 represent fundamental parameters for the design and structural analysis of mechanical components, directly influencing the material's behaviour during production processes and operating conditions. These technical data allow engineers to optimise the steel's performance across the various applications of 18NiCrMo5 and to correctly define the machining parameters.

The density of 18NiCrMo5 is standardised at 7.85 g/cm³, a typical value for alloy steels that reflects the presence of the alloying elements nickel, chromium and molybdenum in the ferritic matrix. This parameter is essential for calculating the specific weight of components and for determining structural stresses during the design phase. The modulus of elasticity shows values between 205-210 GPa according to the technical sources consulted, with the shear modulus settling around 80 GPa. These elastic parameters are fundamental for sizing elements subjected to static and dynamic loads, ensuring correct prediction of elastic deformations.

The thermal properties of 18NiCrMo5 show distinctive characteristics that influence machining processes and heat treatments. The melting temperature shows values ranging between 1430 °C and 1480 °C for the solidus. To obtain a precise value, verification through DTA analyses specific to production batches is required. Thermal conductivity is approximately 40-42 W/(m·K) at 20 °C and decreases with temperature.

The thermal expansion coefficient of 18NiCrMo5 is specified between 11.5-12.0 × 10⁻⁶/K, a value that is compatible with most ferrous alloys and that must be taken into account in the design of mechanical couplings and in the definition of dimensional tolerances for components subject to thermal variations. The electrical resistivity of ~0.16 Ωmm²/m indicates electrical properties typical of alloyed carbon steels, a relevant parameter for applications involving induction heating during heat treatment processes.

05Heat Treatments of 18NiCrMo5 Steel: Case Hardening Processes and Optimal Parameters

The heat treatments of 18NiCrMo5 represent the fundamental process for giving this case-hardening steel the performance characteristics required by the most demanding industrial applications. The combination of case hardening, quench hardening and tempering makes it possible to obtain the typical metallurgical configuration with a hardened surface and a tough core, optimising the balance between surface wear resistance and structural toughness of the component.

5.1Case Hardening of 18NiCrMo5: Parameters and Techniques

The case hardening of 18NiCrMo5 is the fundamental thermochemical treatment for giving the material the performance characteristics required by the most demanding industrial applications. This process of surface carbon enrichment operates through controlled atomic diffusion, optimising the chemical and metallurgical profile of the surface layer to maximise wear resistance and operating life.

The case-hardening temperature of 18NiCrMo5 is set in the 880-950 °C range according to the component specifications and the required penetration depth. For standard automotive applications, the optimal temperature settles at 920-930 °C, ensuring carbon diffusion rates suitable for industrial production cycles. Lower temperatures (880-900 °C) are used for precision components that require rigorous control of dimensional distortions, while higher values (940-950 °C) accelerate the process for high-thickness sections.

The atmosphere control for 18NiCrMo5 case hardening mainly uses endothermic gas + methane (CH₄) mixtures for series applications, with the carbon potential maintained at 0.9-1.1% to prevent the formation of harmful surface carbides. Salt-bath case hardening operates at similar temperatures using mixtures of cyanides and carbonates, while pack (solid) case hardening uses carbonaceous compounds activated with 10-20% BaCO₃.

The case-hardening times of 18NiCrMo5 vary according to the required depth following the parabolic diffusion law. For depths of 0.8 mm, 4-6 hours at 920 °C are required, while thicknesses of 1.5-2.0 mm require 8-12 hours of processing. The cycle includes stages of controlled heating (50-100 °C/hour), isothermal holding and slow cooling down to the hardening temperature.

5.2Hardening of 18NiCrMo5: Temperatures and Quenching Media

The hardening of 18NiCrMo5 represents the critical stage for transforming the austenitic structure into martensite, giving the material the required final mechanical properties. The process requires precise control of temperatures and cooling media to optimise the hardness-toughness balance and to avoid excessive distortions in the finished components.

The hardening temperatures for 18NiCrMo5 are differentiated between the core and the case-hardened surface to optimise the metallurgical transformations. Core hardening is carried out at 840-870 °C with cooling in oil, polymer or salt bath, exploiting the critical temperatures Ac₁ (730 °C) and Ac₃ (815 °C) specific to the alloy. Hardening of the case-hardened surface requires lower temperatures of 800-830 °C to optimise the martensitic transformation of the carbon-enriched layer.

The quenching media for 18NiCrMo5 include mineral oils with high cooling rates for thin sections, polymer solutions for complex geometries that require distortion control, and salt baths for high-thickness components. The choice of quenching medium significantly influences residual stresses and the likelihood of quench cracks, critical parameters for the final quality of the component.

5.3Tempering of 18NiCrMo5: Hardness-Toughness Optimisation

The tempering of 18NiCrMo5 stabilises the martensitic structure obtained from hardening and optimises the hardness-toughness balance through controlled transformations of martensite into more stable structures. This treatment is fundamental for relieving internal stresses and giving the material the impact toughness needed for dynamic applications.

The tempering temperatures of 18NiCrMo5 range between 150-180 °C to maintain high surface hardness (58-62 HRC) with improved core toughness. Higher temperatures (200-250 °C) reduce the hardness but significantly increase the impact toughness, an optimal configuration for components subjected to impact loads. The holding time ranges between 2-4 hours to ensure complete thermal homogenisation of the section.

5.4Quality Control of 18NiCrMo5 Heat Treatments

The quality control of 18NiCrMo5 heat treatments involves systematic checks of the process parameters and of the final characteristics of the component to ensure compliance with the design specifications. The inspection methods include hardness measurements, metallographic analyses and mechanical tests on representative samples from each treatment batch.

The post-treatment hardness verification of 18NiCrMo5 is carried out according to the ISO 6507 standard for Vickers microhardness on a transverse metallographic section. The inspections include hardness profiles at intervals of 0.1 mm for the first 2.0 mm of depth, with particular attention to the surface-core transition zone. The effective case-hardening depth is measured as the distance from the surface to the point with a hardness of 50 HRC according to the ISO 18203:2016 (formerly ISO 2639) standard.

5.5Common Defects and Solutions in 18NiCrMo5 Heat Treatments

The common defects in 18NiCrMo5 heat treatments include geometric distortions, quench cracks, surface oxidation and non-uniformity of the case hardening. Early identification of these problems and the implementation of appropriate solutions is fundamental for maintaining production quality and reducing scrap.

The heat treatment distortions of 18NiCrMo5 can be minimised through appropriate supports during case hardening, control of heating and cooling rates, and optimisation of the quenching sequences. The use of isothermal salt-bath quenching makes it possible to reduce residual stresses while maintaining the mechanical properties required for most industrial applications.

06Industrial Applications of 18NiCrMo5 Steel: Strategic Sectors and Uses

The applications of 18NiCrMo5 span the most demanding industrial sectors, where the combination of surface hardness and core toughness is a fundamental requirement for components subjected to severe stresses. This case-hardening steel finds preferred use in applications that require wear resistance, high mechanical strength and long-term operational reliability.

6.118NiCrMo5 Automotive Applications

The automotive applications of 18NiCrMo5 represent the most significant market segment for this case-hardening steel, where the combination of surface wear resistance and core toughness is decisive for components subjected to severe dynamic stresses. The automotive sector requires materials capable of ensuring operational reliability over high mileage, reducing maintenance costs and improving the vehicle's energy efficiency.

The camshafts in 18NiCrMo5 are the most widespread application, exploiting the surface hardness of 58-62 HRC obtained through case hardening to resist contact wear with tappets and rocker arms. The complex geometry of the cam lobes requires rigorous distortion control during heat treatment, achieved through case-hardening cycles at 920 °C for 6-8 hours followed by differential hardening. The core maintains high toughness (30-35 HRC) to absorb the impacts during valve opening and closing, while the case-hardened surface ensures durability over 200,000+ km of travel.

The transmission components in 18NiCrMo5 include differential gears, half-shafts, planet gears and pinions, where contact fatigue strength is the critical design parameter. The fatigue strength of 18NiCrMo5 after case hardening exceeds that of the base material by 300-400%, allowing a reduction in weight and dimensions while maintaining structural performance.

6.218NiCrMo5 Machine Tool Sector

The machine tool sector uses 18NiCrMo5 for components that require high dimensional precision and wear resistance under continuous operating conditions. Spindles, main shafts, reduction gears and gearbox components exploit the properties obtained through controlled case hardening to ensure machining precision and extended operating life.

Linear guides and sliding components for CNC machines benefit from the high surface hardness combined with the core toughness, essential characteristics for maintaining micrometric precision during prolonged machining cycles. The dimensional stability of 18NiCrMo5 after heat treatment ensures that the tolerances required for high-precision applications are maintained.

6.318NiCrMo5 Hydraulic and Pneumatic Industry

The hydraulic and pneumatic industry extensively uses 18NiCrMo5 for the production of hydraulic cylinders, pistons, valves and components subjected to high pressures. The combination of surface wear resistance and structural toughness makes it possible to withstand the cyclic stresses typical of industrial hydraulic systems, with particular reference to earth-moving machinery and process plants.

The hydraulic cylinders in 18NiCrMo5 typically operate at pressures of 200-350 bar with continuous motion cycles that require wear resistance and dimensional stability. The case-hardened surface (58-60 HRC) resists abrasion from the seals and maintains the surface finish needed for hydraulic sealing, while the tough core absorbs the structural loads without permanent deformation.

6.418NiCrMo5 Aerospace and Defence

The aerospace and defence sector represents a specialist application where 18NiCrMo5 is selected for critical components that require excellent performance under extreme conditions. Landing gear, transmission components for jet engines and flight control actuators exploit the excellent fatigue strength and the ability to maintain stable mechanical properties even under thermal and mechanical stress.

Some military applications include weapon parts and armoured vehicles where certifications according to specific NATO standards are required. Complete material traceability and rigorous quality inspections ensure reliability for components where structural failure entails risks to operational safety.

6.5Performance Comparison vs Other Case-Hardening Steels

The comparison of 18NiCrMo5 with other case-hardening steels highlights specific advantages that justify its selection for critical applications. Compared to 16MnCr5, 18NiCrMo5 offers 40-60% higher hardenability and resistance to temper embrittlement, fundamental characteristics for high-thickness components or complex geometries.

The molybdenum content in 18NiCrMo5 provides superior resistance to austenitic grain growth during case hardening, making it possible to obtain finer microstructures and superior mechanical properties compared to simpler case-hardening steels. This characteristic is particularly advantageous for applications requiring prolonged case-hardening cycles or high temperatures.

07Frequently Asked Questions about 18NiCrMo5 Steel: Technical Answers for Professionals

The most frequently asked questions about 18NiCrMo5 reflect the practical needs of designers, engineers and technicians working in the steel industry. This section gathers the recurring queries regarding the characteristics of 18NiCrMo5, providing precise technical answers based on official standards and specifications to support the correct selection and application of this case-hardening steel.

What is 18NiCrMo5 steel and what are its main characteristics?

18NiCrMo5 is a case-hardening alloy steel alloyed with nickel, chromium and molybdenum, classified as a surface-hardening steel. The designation reflects the chemical composition of 18NiCrMo5, where "18" indicates the carbon percentage (0.18%), while "Ni", "Cr" and "Mo" indicate the presence of nickel (1.20-1.50%), chromium (0.70-1.00% per the historical UNI 7846:1978 standard and 0.80-1.10% for 17NiCrMo6-4, EN ISO 683-3:2022 (formerly EN 10084)) and molybdenum (0.15-0.25%). This steel is particularly valued for its ability to undergo case hardening, a heat treatment that significantly increases the surface hardness while maintaining a tougher and more ductile core.

7.1What are the main industrial applications of 18NiCrMo5?

The applications of 18NiCrMo5 span across industrial sectors where surface hardness and mechanical strength are critical. It is widely used for the production of gears, crankshafts, transmission components and parts subjected to high mechanical loads or repeated stress cycles. Thanks to its wear resistance and its ability to maintain high surface hardness, it is ideal for bearings, bushings and cams. It is commonly used in the construction of industrial machinery, agricultural equipment and machine tools. The properties of 18NiCrMo5 obtained through case hardening make it perfect for applications where a hard, wear-resistant surface combined with a tough core is essential.

7.2How does 18NiCrMo5 compare with other alloy steels?

Compared to other steel alloys, 18NiCrMo5 stands out for its excellent response to the heat treatments of 18NiCrMo5, particularly case hardening. This process delivers an extremely hard, wear-resistant surface while maintaining good toughness in the core. Unlike plain carbon steels, 18NiCrMo5 offers superior mechanical strength and a better ability to withstand dynamic loads and impacts. Compared to alloys without nickel or chromium, this steel ensures superior fatigue strength and greater dimensional stability in service. Its excellent machinability allows the production of high-precision components through CNC machining. However, compared to stainless steels, 18NiCrMo5 has more limited corrosion resistance, potentially requiring protective treatments to extend service life in aggressive conditions.

7.3What are the main mechanical characteristics of 18NiCrMo5?

The mechanical characteristics of 18NiCrMo5 are defined by balanced properties that make it ideal for components subjected to high stress. The typical tensile strength ranges from 800 to 1100 MPa, depending on the heat treatment applied. The yield strength generally lies between 500 and 700 MPa, ensuring a good capacity to absorb elastic loads before permanent deformation. After case hardening, the surface hardness can reach values between 58 and 62 HRC, providing excellent wear resistance. The toughness of the core, combined with the surface hardness, allows the material to withstand repeated load cycles without fracturing.

7.4What is the difference between 18NiCrMo5 and equivalent designations?

18NiCrMo5 per UNI 7846:1978 (historical standard) corresponds to the current 17NiCrMo6-4 (EN 1.6566) per EN ISO 683-3:2022 (formerly EN 10084:2008) with slight variations in composition. The equivalent AISI designation is 4317, while the British BS is 815M17. On request, this steel grade can be supplied with additions of lead (Pb) 0.15-0.35% or sulphur (S) 0.020-0.035% to improve machinability. The main differences concern slightly different tolerances in the alloying-element contents and national standard specifications, but the mechanical performance remains substantially equivalent across the different designations.

08The Siderticino Offer for 18NiCrMo5 Steel: Specialist Solutions for Case-Hardening Applications

To meet the application needs in the automotive, heavy engineering and industrial sectors described in the previous sections, Siderticino supplies 18NiCrMo5 steel of certified quality in compliance with UNI 7846:1978 and EN ISO 683-3:2022 (formerly EN 10084) (grade 17NiCrMo6-4, material number 1.6566). Following the quality approach adopted for other case-hardening steels in the company range, full material traceability and compliance with the quality standards required for critical 18NiCrMo5 applications, where reliability is a non-negotiable parameter, are guaranteed.