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Material data sheet

Steel grade

Last revised: Tue, 07 Feb 2023 13:42:34 GMT

General Information

Ovako 677L & 677Q is an air-hardening bearing steel with high mechanical strength and fatigue properties. By using gas cooling or air-hardening it is possible to reduce the amount of distortion. Additionally the use of quenching medias such as oil and salt can be avoided, which improves both safety and environment.

  • Through hardenability corresponding to a bar with approx. ∅40 mm (cooling in still air)
  • Can be induction or flame hardened
  • Good machinability in soft annealed condition
  • Machinable in hardened condition using hard-turning techniques
  • Good dimensional stability
  • Corresponds to BQ and IQ specifications
  • Delivered in soft annealed condition

Ovako 677L - BQ ( Bearing Quality) - Standard

Ovako 677Q - IQ (Isotropic Quality) - Due to a reduced sulphide inclusion content and a finer oxide inclusion distribution, Ovako 677Q is a steel with isotropic properties with excellent fatigue strength in both transverse and longitudinal directions.


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

BQ-Steel® is a bearing quality clean steel optimized for fatigue strength and is also ideal for new design solutions outside the bearing industry.

Similar designations


Steel cleanliness

Micro inclusions - BQ    Macro inclusions - BQ 
Applied standard ASTM  45   Applied standard  

ISO 3763 (Blue fracture)

 Statistical testing on billets
Sampling ASTM  A295   Sampling
Maximum average limits       A       B       C       D   Limits < 2,5 mm/dm2
Th He Th He Th He Th He  
2.0 1.5 0.8 0.1 0 0 0.5 0.3  
Micro inclusions - IQ    Macro inclusions - IQ 
Applied standard DIN 50602  K1   Applied standard

ISO 3763

(Blue fracture)

10 M Hz UST

(Ovako internal procedure)

Sampling Six random samples from final product dimension   Sampling Statistical testing on billets

The limit is dimension dependent. The average rating of six samples should not exceed the limits given in the graph


< 1mm


<18 defects /dm3

> 0.2 mm FBH


Tempering response Ovako 677

Transformation diagrams


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.