Filter datasheet


Material data sheet

Steel grade

Last revised: Thu, 01 Oct 2020 13:09:11 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.

(Bearing Quality) is a bearing quality clean steel optimized for fatigue strength by a strict control of steel cleanliness. BQ-steel is also ideal for new design solutions in a wide array of demanding applications outside the bearing industry that require longer performance and higher loads. The BQ-steel offer is the result of the Ovako clean steel program. Purity of production means that the material has significantly smaller inclusions compared to conventional steel and, as a result, the fatigue strength of the steel is increased dramatically. Use of the material allows components to be manufactured in smaller sizes. The BQ-steel  has for decades been the problem-solver.

(Isotropic Quality) is an isotropic quality ultra clean steel. IQ-Steel is optimized for fatigue strength by a strict control of steel cleanliness. IQ-Steel, a further development of BQ-Steel, is an isotropic and ultra clean steel with properties that match re-melted steels. Based on thousands of examinations by Ovako into the effects of defects on fatigue performance, the metallurgy of IQ-Steel is purer and far more consistent than conventional grades, and designed specifically to perform well in multi axial loading. This enables the manufacturing of lighter, slimmed down components like gears, bearings and other critical parts. The steels are helping our customers to achieve new design solutions and implement higher standards of finished product performance. Key to these practical advantages are Ovako’s own unique, clean and consistent modern steelmaking processes that remove harmful inclusions and impurities from within the steel. IQ-Steels contain smaller and more fragmented inclusions and can handle much higher mechanical forces in all directions than conventional steels. IQ-Steels are newer, but already now well established in high pressure automotive applications. Modern diesel engines, with high and cyclic injection pressures, have proven to be an ideal application. Transmission components are another emerging area of strong interest.

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

Contact us

Would you like to know more about our offers? Don´t hesitate to contact us:

Via e-mail: 

Via telephone: +46 8 622 1300

For more detailed information please visit




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.