BQ Steel and IQ Steel



For components and systems to survive a specified load collective under a certain amount of time, the purity of the steel is a key enabler. Not only is there a need for high absolute values for performance in the steel but it needs to be consistent and provide a narrow span in each relevant property. Over decades, Ovako has provided the market with such products for all kinds of engineering steel grades when they are processed to reach the BQ-Steel” and IQ-Steel”‘ performance levels.

Independently of which steel grade you need, it is important to define what you demand from the steel you acquire. In simple terms, this divides into three categories

1. Direct cost efficiency

2. Direct value creation

3. End user value creation

The common denominator in providing high fatigue resistance is the metallurgically design of small and controlled inclusions. BO-Steel and IQ-Steel represent the two highest steps on the “fatigue ladder” for steels produced in high volume production.

IQ-Steel is a top premium level due to the isotropic properties providing equal strength in all loading directions, which otherwise is a well-established but little known fact in conventional steels. This enables designers to design towards equal strength in the material independent of the direction of the applied loads.


In fatigue strength, the IQ-Steels are on par with some of the most advanced remelted steels and outperform standard ESR remelted steels. The carefully controlled IQ-Steel process achieves both dramatically reduced direct cost as well as a narrow spread o· properties within a large number of components. Figure 1 shows results from a comparative rotating bending test of a remelted VAR steel and an Ovako IQ-steel, 35 mm ba1 heat treated to 53 HRC. In this particular case the mean values are similar, but the IQ-steel has provided less scatter.

Advantages of BQ-Steel and IQ-Steel

• Consistent quality for secure and stable product.on of end-user components

• Improved bending and contact fatigue strength

• Increased load per weight capacity, e.g. Nm/kg

• Decreased cost per load unit, e.g. €/Nm

• Component size reduction at fixed torque

The price of the IQ-Steel produced cost-efficiently in high volumes is significantly lower than the competing remelted solution. In Figure 2 the principal relationships between the steel price and fatigue performance versus metallurgical routes are displayed.

Common grades with BQ and IQ-Steel performance

20MoCr4124Carburizing steel for heavier sections. available as IQ0.
20N CrMo2-2152SAE 8620 available as BQ0.
20N1Mo9-7*158Steel giving reduced surface ox dat1on after gas carburizIng, available as IQ0.
18CrNiMo7-6159Carburizing steel used for bearing and transmission
components, available as both IQ and BQ
20MnCr5236For small-sized transmIssIon components, mooerate core
Hardness, avaiable as IQ
12NiCr14-6*245SAE 3311, available as BQ0.
18NiCrMo14-6255High hardenability carburising steel, available as both IQ and BO0.
16CrMnN1Mo9-5-2•277Steel suitable for carburizing and nitriding Possible to gas/air harden. available as IQ0.
42CrMo4326SAE 4140, available as BQ0.400.
40NICrM07-3'355SAE 4340 modified with V, available as BQ0.400.
32CrMoV12-1 0398Steel suitable for deep nitriding, available as IQ0.320.
42N1S1CrMo8-7·497High-strength. high-toughness steel known as 300M,
available as IQ
30NiCrMo 16·6498High-strength, high-toughness steel, available as IQ0.300.
30MoCrV20-7*499Temperature resistant carburizing steel0.
50CrMo4528Medium carbon Q& T steel suitable for surface induction Hardening, available as both IQ and BQ0.510.
51CrV4593High strength alloyed with chromium and vanadium,
available as IQ
66SIMnC rMo6-6-4 •677Bearing steel suitable for gas/air hardernng, available as both IQ and BQ0.671.
100Cr6803The most widely used bearing steel with a hardenability for small components (wall thickness 17 mm). available as both IQ and BQ1.
100CrMo7824Increased hardenability with Cr and Mo for small-and medium-sized components (wall thickness 20 mm).
available as both IQ and BQ
100CrMo7-3825Increased hardenability with Cr and Mo for medium-sized components (wall thickness 30 mm), available as both IQ and BQ0.950.
100CrMo7-4826Increased hardenability with Cr and Mo for Medium-and large-sized components (wall thickness 50 mm), available as BQ0.950.
100CrMnMoSi8-4-827Increased hardenability with Cr, Mo and S1 foe large-sized components (wall thickness 75 mm). available as BQ0.950.
1 00CrMnS14-4831Increased hardenability with Cr, Mn and Si for small and medIum-sized components (wall thickness2 0 mm). available as BQ0.950.61.11.0
100CrMnSi6-6832Increased hardenability with Cr. Mn and S1 for medium sized
components (wall thickness 40 mm). available as BQ
100CrMnSi6-837Increased hardenability with Cr, Mn and Si for small and Medium-sized components (wall thickness 30 mm).
available as BQ
• Designation followed by "*" is not an official EN standard grade but named according to the rules in EN 10027