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Seamless steel tubes

Fields of use

Roller bearings, injection nozzles for common rail diesel engines, hydraulic cylinders, rollers, heavy-duty gears such as those used for wind turbines, heavy-duty or very demanding components for mechanical engineering, etc. Ovako steels are available as seamless steel tubes, as rolled or forged rings up to 3 m in diameter or as bar stock.
As well as steels described in more detail below, which can be supplied by the Embrach service centre, Ovako also produces other grades of steel. These are available ex works with the relevant delivery time (8-12 weeks) and quantity (minimum 8 tonnes).

Description

Seamless Ovako 280 mechanical engineering steel tube
Ovako 280 are produced from a pure steel and are seamless. It is available in many dimensions up to a maximum external diameter of 256.5mm.
Delivery dimensions from the Embrach service centre (PDF KB xx)

Ovako 803 (100Cr6) and Ovako 824 (100CrMo7) roller bearing steel tubes
This steel is characterised by its high resistance to fatigue and wear.
Ovako 803:  Is characterised by its high resistance to fatigue and wear. The tubes are supplied in an annealed state and can be machined well. Up to 60-65HRC can be achieved through martensitic hardening/annealing.
Ovako 824: Is suitable for through hardening of thicker walls. This steel also has a high fatigue strength, an excellent resistance to wear and good level of toughness. This grade is suitable for martensitic and bainitic hardening.

Properties


Ovako 280
Are normally supplied as hot-rolled tubes. The following mechanical properties are the result:

Wall thickness mmYield stress Rp min  MpaTensile strength Rm minMPABreaking elongation A5 min %Hardness approx. HBImpact energy Kv min. at 20°C J
<=255006702022527
>254706402022027

Welding: Good welding properties, is suitable for all conventional welding procedures.Normalising: 900-920°C, cooling in calm air.Stress relief annealing: 550-600°C, holding time of 1-2 hours, cooling in the oven or air.Quenching and tempering: 900-920°C, quenching in water and annealing at 500°C for approx. 1 hour.Carburization: Carburization at 850-950°C, hardening at 780-830°C, quenching in oil or graduated quenching, annealing at 150-200°C for 1 hour, normal surface hardness 58-63HRC.Nitrogen hardening: 500-520°C, surface hardness approx. 650HV. Also suitable for plasma nitriding.

Ovako 803

Are normally supplied as soft-annealed tubes. The following mechanical properties can be achieved:

StateYield stress Rp min  MpaTensile strength Rm minMPABreaking elongation A5 min %Hardness
Hot-rolled, soft-annealed41070027195 HB
Cold-drawn70088013210 HB
Martensitically hardened17002300261 HRC
Bainitically hardened20002200759 HRC

Forging: 800-1100°C, cooling in calm air.Soft annealing: Heating to 820°C /1 hour, holding at 820°C 2 hours, cooling from 820°C to 740°C / 1 hour, cooling from 740°C to 690°C /10 hours, cooling in calm air.Stress relief annealing: 550-650°C, holding time of 1 hour, air-cooling.Martensitic hardening: 830-870°C / 10-60 minutes, quenching in oil and annealing within 2 hours at a min. 160°C  as per the datasheet.Bainitic hardening: 850-875°C / 10-60 minutes, quenching in salt bath 220-250°C /3-7 hours as per the datasheet.Annealing: 160-570°C as per the datasheet, cooling in calm air.

Ovako 824

Are normally supplied as soft-annealed tubes. The following mechanical properties can be achieved:



Forging: 800-1100°C, cooling in calm air.
Soft annealing: Heating to 820°C /1 hour, holding at 820°C 2 hours, cooling from 820°C to 740°C / 1 hour, cooling from 740°C to 690°C /12 hours, cooling in calm air.
Stress relief annealing: 550-650°C, holding time of 1 hour, air-cooling.
Martensitic hardening: 830-870°C / 10-60 minutes, quenching in oil and annealing within 2 hours.
Bainitic hardening: 850-875°C / 10-60 minutes, quenching in salt bath 220-250°C /3-8 hours.
Annealing: 160-500°C, cooling in calm air.

Product offers from Stahl-Contor from the Embrach service centre

 

Material
number
DescriptionDelivery
condition
Dimensions off the shelfTypical applications
Works standardOvako 280Hot-rolledExternal D = 60-255mmComponents, for which the following properties are sought-after:
• Can be chrome-plated
• Can be hardened
• Can be nitrified
• Can be welded
• Fine-grain steel
• Dimensional stability
Works standardOvako 803Soft-annealedExternal D = 30-200mmComponents, for which the following properties are sought-after:
• Major hardness
• Wear resistance
• Endurance limit
• Dimensional stability
• Through-hardened up to approx. 25mm

Works standardOvako 824Soft-annealedExternal D up to 200mmComponents, for which the following properties are sought-after:
• Major hardness
• Wear resistance
• Endurance limit
• Dimensional stability
• Through-hardened up to approx. 50mm

IQ Steel (isotropic quality)

Steel for use in roller bearings must satisfy very high demands. The Hertzian stress in ball bearings, the fatigue caused by the rolling over at high speeds, the demand for good machinability lead to the constant further development of steel grades at Ovako.

Alloying elements influence what properties can be achieved with heat treatment. Thanks to the use low-alloyed, clean scrap, an careful smelting process in the electric furnace and a sophisticated system to add the alloying elements, Ovako achieves a major similarity in the chemical composition of various fusions/batches.
However, it is not just the elements that are added to the steel which define the quality. The defects in the steel, which you do not want to have, are just as important. Defects are understood to be non-metallic inclusions, segregations and pores, for example. Non-metallic inclusions are sulphides and oxides.

In a normal construction steel, there are up to 500 characteristics, which are greater than 100 micrometres in every 10 kg of steel, considerable quantities of mm-sized defects and in a cast of 100 tonnes, there are over 500,000 inclusions. In an IQ steel, there are up to 5 characteristics, which are greater than 100 micrometres in every 10 kg of steel, immeasurable quantities of mm-sized defects and in a cast of 100 tonnes, there are 10 x less inclusions than in normal steel.

The non-metallic inclusions in steel have negative influences on the consistency and hardness, on the fatigue and weldability. During the roller process, these inclusions are deformed in the direction of rolling, making them complicit in the different mechanical grades in the lateral and longitudinal directions.

IQ steel stands for the particularly pure and homogeneous steels from Ovako. For example, it is used in injection pumps for diesel engines and has also contributed to reducing consumption by 1 litre of diesel per 100 km. Other manufacturers can only achieve the mechanical values through the electro-slag remelting process (ESR). However, the ESR process has a much greater impact on the environment and the cost of production is also greater. IQ steel is also used in gears for offshore wind farms. The operators want to avoid expensive repairs here.

In January 2013, Patrik Ölund, head of development at Ovako, received the Kami Prize in Sweden. He received this prize for the development of the IQ steel. This prize is awarded once a year for outstanding developments in the Swedish steel industry.


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