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Last revised: Tue, 07 Feb 2023 13:38:00 GMT

18NiCrMo14-6

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General Information

18NiCrMo14-6 is a case hardening steel with high toughness used for bearing and transmission components. There are two different versions of the grade with high cleanliness requirements. The high hardenability ensures a through hardenability of large sections.

255G - Bearing quality (BQ) variant with low sulphur content and high cleanliness demands

255Q - Isotropic quality (IQ) with isotropic properties and improved fatigue strength due to higher cleanliness levels, and a finer size and distribution of non-metallic inclusions

IQ-Steel®

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

BQ-Steel®
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

1.3533

Chemical composition

Variant	Cast	Weldability		C %	Si %	Mn %	P %	S %	Cr %	Ni %	Mo %
255G	IC	CEV 0.96_max	Min	0.15	0.15	0.40	-	-	1.30	3.25	0.15
255G	IC	Pcm 0.41_max	Max	0.18	0.40	0.70	0.025	0.005	1.60	3.75	0.25
255Q	IC	CEV 0.96_max	Min	0.15	0.15	0.40	-	-	1.30	3.25	0.15
255Q	IC	Pcm 0.41_max	Max	0.18	0.40	0.70	0.025	0.002	1.60	3.75	0.25
EN ISO 683-17	Std	CEV _max	Min	0.15	-	0.40	-	-	1.30	3.25	0.15
EN ISO 683-17	Std	Pcm _max	Max	0.20	0.40	0.70	0.025	0.015	1.60	3.75	0.25

Mechanical Properties

Variant	Condition	Format	Dimension [mm]	Hardness
Rp_0.2 * R_eh, ** R_el
255G	+SA	All formats	24 < 190	220 HB typical
255Q	+SA	All formats	24 < 120	220 HB typical

Transformation temperatures

	Temperature °C
AC1	695
AC3	805

Heat treatment recommendations

Treatment	Condition	Temperature cycle	Cooling/quenching
Hot forging	+AR	800-1200°C	In air
Normalizing	+N	860-890°C	In air
Soft annealing	+SA	600-670°C / 2h	In air
Carburizing	+C	850-930°C Carbon potential see diagram
Hardening	+Q	840-890°C when Q/T is applied	In oil
Hardening	+Q	780-830°C when hardening os as-carburized component	In oil
Tempering	+T	160-250°C	In air

Heat Treatment Guide generated Graphs

The following graphs are generated from a theoretical model. For further info see the Heat treatment guide module. Select a specific grade version for individual display.

Hardenability

Jominy hardenability according to ASTM A255. 255G data is average value with +/- standard deviation. En ISO 683-17 according to +H variant

Steel cleanliness

Micro inclusions - Steel grade 255G									Macro inclusions - 255G
Applied standard	ASTM 45								Applied standard	ISO 3763 (Blue fracture)
Sampling	ASTM A295								Sampling	Statistical testing on billets
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	0.4

Micro inclusions - Steel grade 255Q									Macro inclusions - 255Q
Applied standard	DIN 50602 K1								Applied standard	10 M Hz UST (Ovako internal standard)
Sampling	Six random samples from final product dimension								Sampling	Statistical testing on billets
Limits	The limit is dimension dependent. The average rating of six samples should not exceed the limits given in the graph								Limits	< 10 defects/dm3 > 0,2 mm FBH

IQ

CCT

Carburizing

SUSTAINABILITY-ENVIRONMENTAL IMPACT DATA

At Ovako sustainability and reduction of our environmental impact is a major focus in everything we do.
Further information is found here.

In many international comparisons the crude steel Scope 1-2 emission is a key parameter, ie. the CO₂ emission from the steel works itself.
As of 1 January 2022 we carbon offset all our scope 1 and 2 volume shown below.

Steel works	Hofors	Smedjebacken	Imatra
CO2e/kg	120	62	76

To get the full picture of our products environmental impact we have to look at all of our CO₂ emission sources.
Not only the steel work Scope 1-2 itself, but all operations downstream in our production, heating and heat treatment furnaces etc (full scope 1-2) as well as all the emission from input material, eg. alloys, scope 3.

Steel Grade	Format	Condition	Scope 1-3 (CO2e kg /1000 kg steel)	Climate compensated Net emission = Scope 3 (CO2e kg /1000 kg steel) Scope 1 - 2 = 0 (compensated)
255	Round bar	+AR	1162	769
255	Round bar	+SA	1170	773
255	Tube,wall	+AR	1239	838
255	Tube,wall	+SA	1240	838

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: info@ovako.com

Via telephone: +46 8 622 1300

For more detailed information please visit http://www.ovako.com/en/Contact-Ovako/

Disclaimer

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.

General information
Chemical composition
Mechanical properties
Transformation temp.
Heat treatment
HTG Graphs
Hardenability
Sustainability