Grade B21 Cr-Mo-V - ASTM A 540/A540M-2024

Grade	Grade B21
Other Names
Corresponding Standard	ASTM A540/A540M-2024 Alloy-steel Bolting for Special Applications
Classification	Alloy Steel

Grade B21 Chemical Element Composition Content (%)

Component	C	Si	Mn	P ^①	S ^①	Cr	Mo	V
Minimum Value	0.36	0.15	0.45	-	-	0.8	0.5	0.25
Maximum Value	0.44	0.35	0.7	0.025	0.025	1.15	0.65	0.35

Grade B21 Mechanical Properties

diameter d mm	Mark	Tensile Strength σ_b Mpa	Specified Plastic Yield Strength Rp_0.2 Mpa	Elongation or Extension Rate δ %	Reduction of Area ψ %	Hardness HBW
d≤50	Class 5	≥825	≥725	≥15	≥50	241~285
50＜d≤150	Class 5	≥795	≥690	≥15	≥50	248~302
150＜d≤205	Class 5	≥795	≥690	≥15	≥50	255~311
d≤75	Class 4	≥930	≥825	≥13	≥45	269~331
75＜d≤150	Class 4	≥930	≥825	≥13	≥45	277~352
d≤75	Class 3	≥1000	≥895	≥12	≥40	293~352
75＜d≤150	Class 3	≥1000	≥895	≥12	≥40	302~375
d≤100	Class 2	≥1070	≥965	≥11	≥40	311~401
d≤100	Class 1	≥1140	≥1035	≥10	≥35	321~429

GradeB21 Corresponding Standards(Same grade name, different standards)

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