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Material data sheet

Steel grade

Last revised: Thu, 23 Feb 2023 16:19:39 GMT

General Information

18CrNiMo7-6 is a case hardening steel with high toughness. There are a number of variants with high cleanliness requirements. All variants  possess tighter composition ranges compared to the standard. One variant is produced with the quality class IQ (isotropic quality). This ensures a very low number of elongated sulphide inclusions which will give more isotropic properties. The high oxidic cleanliness will enable the steel to meet the same high cleanliness demands as for re-melted qualities.

Grade 159A  -  Variant with low sulphur content and high cleanliness demands

Grade 159B  -  Variant with controlled sulphur content for consistent machinability and +H hardenability

Grade 159Q  -  Isotropic properties (IQ) and better fatigue strength due to higher cleanliness levels, and a finer size and                                                               distribution of non-metallic inclusions

Grade 159X  -  Variant with controlled sulphur content for consistent machinability and +H hardenability

Grade 159S   - Variant with increased sulphur content.

Grade 4761(MoCN216) - Low sulphur  variant  of  Imatra



IQ-Steel® is an isotropic quality ultra clean steel optimized for high fatigue strength under multi axial loading.

Similar designations

1.6587, AISI4820, DIN17CrNiMo6, 18CND6, EN ISO 683-17

Austenitization temperature of Ovako 159X: 845°C    

Carburizing response - Ovako 159

Steel cleanliness

Micro inclusions - steel grade 159X   Macro inclusions - 159X
Applied standard ASTM  E45   Applied standard

ISO 3763

(Blue fracture)

Sampling ASTM  A295   Sampling Statistical sampling on billets


average limits

A B C D   Limits <2,5 mm/dm2
Th He Th He Th He Th He  
2.0 1.5 1.5 0.5 0.0 0.0 1.0 1.0  
Micro inclusions - IQ - steel grade 159Q   Macro inclusions - IQ - 159Q
Applied standard DIN 50602  K1   Applied standard

10 MHz UST (Ovako internal


Sampling Six random sample from final product   Sampling Statistical sampling on billets

The limits is dimension dependent. The average rating of six samples should not exeed

the limits given in the graph.


<10 defects/dm3 >0,2 mm



Other properties (typical values)

Youngs module (GPa)Poisson´s ratio (-)Shear module (GPa)Density (kg/m3)
210 0.3 80 7800
 Average CTE 20-300°C (µm/m°K) Specific heat capacity 50/100°C (J/kg°K) Thermal conductivity Ambient temperature (W/m°K) Electrical resistivityAmbient temperature (µΩm)
 12  460 - 480  40 - 45  0.20 - 0.25

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The information in this document is for illustrative purposes only. The data and examples are only general recommendations and not a warranty or a guarantee. The suitability of a product for a specific application can be confirmed only by Ovako once given the actual conditions.The purchaser of an Ovako product has the responsibility to ascertain and control the applicability of the products before using them. Continuous development may necessitate changes in technical data without notice. This document is only valid for Ovako material. Other material, covering the same international specifications, does not necessarily comply with the properties presented in this document.