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Home > Products > Hot-rolled products > Steel grades > Boronalloyed quenched and tempered steel

Boronalloyed quenched and tempered steel

General Information

These steel grades belong to the product category of quenched & tempered steels, and features outstanding forming properties in the soft delivery state and high strength after heat treatment (hardening). The materials strength is propagated by adding a small fraction of boron to the carbon, manganese and chromium composition.

Form of delivery

This steel grade is available as hot rolled coil (pickled, unpickled) in nominal thicknesses of 2,0 to 12,70 mm and in widths according to the Salzgitter Flachstahl delivery program.

Chemical composition (melt analysis in percent by weight)

Range of chemical composition guaranteed
(differing ranges by prior agreement)

Sorte	C	Mn	Si	P	S	Al	N	Cr	Ti	B
				max.	max.		max.
22MnB5	0,19 - 0,25	1,10 - 1,40	0,10 - 0,40	0,025	0,010	0,015 - 0,080	0,010	0,10 - 0,30	0,020 - 0,050	0,0010 - 0,0050
24MnB5	0,21 - 0,26	1,15 - 1,50	0,10 - 0,40	0,025	0,010	0,015 - 0,080	0,010	0,10 - 0,30	0,020 - 0,050	0,0010 - 0,0050
26MnB5	0,22 - 0,28	1,10 - 1,50	0,10 - 0,40	0,025	0,010	0,015 - 0,080	0,010	0,10 - 0,30	0,020 - 0,050	0,0010 - 0,0050
30MnB5	0,27 - 0,33	1,15 - 1,45	0,10¹⁾ - 0,40	0,025	0,010¹⁾	0,015 - 0,080	0,010	0,10¹⁾ - 0,30¹⁾	0,020¹⁾ - 0,050¹⁾	0,0010¹⁾ - 0,0050

¹⁾: restriction according to the specification of the norm

Typical chemical composition

Sorte	C	Mn	Si	P	S	Al	N	Cr	Ti	B
22MnB5	0,22	1,25	0,25	0,013	0,004	0,040	0,0040	0,14	0,030	0,003
24MnB5	0,24	1,25	0,25	0,015	0,004	0,035	0,0035	0,12	0,030	0,0030
26MnB5	0,26	1,25	0,23	0,012	0,003	0,040	0,0035	0,13	0,030	0,0028
30MnB5	0,29	1,25	0,25	0,015	0,004	0,035	0,0035	0,13	0,030	0,0032

Typical mechanical properties derived from tensile tests transversal to rolling direction (reference value for a hot rolled coil)

Grade	Yield strength R_p0,2	Tensile strength R_m	Total elongation A
	[MPa]	[MPa]	A₈₀ [%]	A₅ [%]
22MnB5	450	630	18	24
24MnB5	470	650	17	23
26MnB5	490	670	17	22
30MnB5	510	700	15	20

Thickness: 2 to 3 mm

Microstructure

These boronalloyed quenched and tempered steel grades in hot rolled state usually have a ferritic-pearlitic microstructure with a typical grain size of > 9 ASTM according to DIN 50602.

Microstructure 24MnB5, 200:1

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Microstructure 30MnB5, 200:1

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Examples of use

Thanks to the combination of formability and temperability, the automotive industry takes advantage of these steel grades especially for the production of supporting body parts (motor vehicles) and other safety-relevant components. Examples are the B-pillar, side impact protection, chassis components or bumpers.

Within the automotive industry, welded precision tubes made of these steel grades are, for instance, used to make stablizers, axle driving or gearbox shaft and other parts relevant to passive security. Another application field for them is the production of boiler tubes.

Pdf-Download:

22MnB5

24MnB5

26MnB5

30MnB5

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