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Boron-alloyed 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. Currently, Salzgitter Flachstahl can supply manganese-boron Steels of 8MnB5 to 46MnB5 and customer-specific analysis variants by arrangement.

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)

Grade C Mn Si P S Cr Ti B
max. max.
8MnB5 0.04 - 0.10 0.60 - 1.00 0.10 - 0.35 0.02 0.007 0.35 - 0.55 0.010 - 0.045 0.0010 - 0.0050
14MnB5 0.11 - 0.17 1.00 - 1.55 0.10 - 0.35 0.02 0.007 0.25 - 0.40 0.010 - 0.045 0.0005 - 0.0050
20MnB51) 0.17 - 0.23 1.10 - 1.40 ≤ 0.40 0.025 0.035 - - 0.0008 - 0.0050
22MnB5 0.20 - 0.27 1.05 - 1.40 0.15 - 0.35 0.02 0.007 0.20 - 0.25 0.010 - 0.045 0.0005 - 0.0050
22MnB5 0.15 - 0.22 1.05 - 1.40 0.30 - 0.45 0.02 0.007 0.30 - 0.40 0.010 - 0.045 0.0010 - 0.0050
22MnB5 0.20 - 0.27 1.10 - 1.40 0.15 - 0.35 0.02 0.007 0.20 - 0.25 0.010 - 0.045 0.0010 - 0.0050
22MnB5 0.18 - 0.26 1.00 - 1.50 0.15 - 0.35 0.02 0.007 0.20 - 0.40 0.010 - 0.045 0.0010 - 0.0050
24MnB5 0.21 - 0.26 1.15 - 1.50 0.10 - 0.40 0.025 0.010 0.15 - 0.25 0.020 - 0.050 0.0010 - 0.0050
26MnB5 0.22 - 0.29 1.15 - 1.45 0.15 - 0.35 0.02 0.005 0.15 - 0.25 0.010 - 0.045 0.0010 - 0.0050
26MnB5 mod. 0.22 - 0.29 1.05 - 1.35 0.15 - 0.35 0.02 0.005 0.25 - 0.35 0.010 - 0.045 0.0010 - 0.0050
27MnB5 0.25 - 0.32 1.00 - 1.35 0.15 - 0.35 0.02 0.005 0.25 - 0.35 0.010 - 0.045 0.0010 - 0.0050
27MnCrB5-21) 0.24 - 0.30 1.10 - 1.40 ≤ 0.40 0.025 0.035 0.30 - 0.60 - 0.0008 - 0.0050
27MnCrB5-2 0.25 - 0.32 1.15 - 1.45 0.15 - 0.35 0.02 0.005 0.35 - 0.45 0.010 - 0.045 0.0010 - 0.0050
30MnB5 0.27 - 0.33 1.15 - 1.45 ≤ 0.40 0.025 0.035 - - 0.0008 - 0.0050
30MnB5 0.26 - 0.33 1.05 - 1.45 0.15 - 0.35 0.02 0.007 0.25 - 0.35 0.010 - 0.045 0.0010 - 0.0050
30MnB5 0.26 - 0.33 1.15 - 1.50 0.15 - 0.35 0.02 0.007 0.15 - 0.25 0.010 - 0.035 0.0010 - 0.0050
33MnCrB5 0.30 - 0.37 1.15 - 1.50 0.15 - 0.35 0.02 0.005 0.45 - 0.55 0.010 - 0.045 0.0010 - 0.0050
34MnB5 0.31 - 0.39 1.10 - 1.50 0.15 - 0.35 0.02 0.005 0.15 - 0.25 0.010 - 0.045 0.0010 - 0.0050
34MnB52) 0.33 - 0.40 1.10 - 1.40 0.15 - 0.35 0.02 0.005 0.10 - 0.20 0.025 - 0.065 0.0010 - 0.0050
37MnB51) 0.35 - 0.40 1.15 - 1.45 ≤ 0.30 0.025 0.025 ≤ 030 - 0.0008 - 0.0050
38MnB51) 0.36 - 0.42 1.15 - 1.45 ≤ 0.40 0.025 0.035 - - 0.0008 - 0.0050
40MnB5 0.36 - 0.43 1.05 - 1.40 0.15 - 0.35 0.02 0.005 0.45 - 0.60 0.020 - 0.055 0.0005 - 0.0050
46MnB4 0.43 - 0.50 0.65 - 1.05 0.15 - 0.35 0.02 0.017 0.30 - 0.40 0.015 - 0.055 0.0005 - 0.0050

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

Grade Yield strength Rp0,21) Tensile strength Rm1) Total Elongation A1) Yield strength Rp0,22) Tensile strength Rm2) Total Elongation A52)
[MPa] [MPa] A80 [%] A5 [%] [MPa] [MPa] [%]
8MnB5 280 - 490 470 - 570 ≥ 16 ≥ 20 290 - 460 450 - 550 ≥ 18
20MnB5 300 - 530 490 - 650 ≥ 15 ≥ 19 310 - 540 470 - 600 ≥ 16
22MnB5 310 - 550 500 - 700 ≥ 15 ≥ 18 310 - 550 480 - 670 ≥ 15
26MnB5 360 - 580 580 - 750 ≥ 12 ≥ 14 340 - 570 520 - 700 ≥ 11
27MnB5 370 - 590 590 - 760 ≥ 11 ≥ 13 350 - 570 530 - 720 ≥ 10
27MnCrB5-2 320 - 570 590 - 760 ≥ 11 ≥ 13 300 - 580 530 - 730 ≥ 10
30MnB5 360 - 600 610 - 760 ≥ 10 ≥ 12 340 - 590 600 - 750 ≥ 10
33MnCrB5 380 - 610 610 - 770 ≥ 9 ≥ 12 350 - 610 610 - 760 ≥ 10
34MnB5 380 - 620 620 - 820 ≥ 9 ≥ 12 350 - 620 620 - 790 ≥ 9
37MnB5 380 - 680 630 - 830 ≥ 8 ≥ 11 380 - 630 630 - 810 ≥ 9
40MnB5 390 - 780 650 - 950 ≥ 7 ≥ 11 400 - 760 640 - 890 ≥ 7
(46MnB5) 400 - 820 670 - 990 ≥ 6 ≥ 9 430 - 820 670 - 950 ≥ 6

Microstructure

These boron-alloyed 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
Microstructure 30MnB5, 200:1

Examples of usage

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 stabilizers, axle driving or gearbox shaft and other parts relevant to passive security. Another application field for them is the production of boiler tubes.

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