Assertion: ppm b | /r/CapableOf | replace equivalent 0.4%
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text: Boron is effective at very low concentrations - 30 ppm B can replace an equivalent 0.4% Cr, 0.5% C, or 0.12% V. 30 ppm B has also been shown to increase depth of hardening (~ +50%) in a low alloy steel - thought to be due to its retardation of the transformation from martensite to softer bainite, ferrite, or pearlite.