Grade B24 4340 Mod. - ASTM A 540/A540M-2024

Grade	Grade B24
Other Names
Corresponding Standard	ASTM A540/A540M-2024 Alloy-steel Bolting for Special Applications
Classification	Alloy Steel

Grade B24 Chemical Element Composition Content (%)

Component	C	Si	Mn	P ^①	S ^①	Cr	Ni	Mo
Minimum Value	0.37	0.15	0.7	-	-	0.7	1.65	0.3
Maximum Value	0.44	0.35	0.9	0.025	0.025	0.95	2	0.4

Grade B24 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	Impact Energy Absorption KV2 J
d≤150	Class 5	≥825	≥725	≥15	≥50	248~311	-12.2°C：①
150＜d≤200	Class 5	≥795	≥690	≥15	≥50	255~321	-12.2°C：①
200＜d≤240	Class 5	≥795	≥690	≥15	≥50	262~321	-12.2°C：①
d≤75	Class 4	≥930	≥825	≥13	≥45	269~341	-12.2°C：①
75＜d≤150	Class 4	≥930	≥825	≥13	≥45	277~352	-12.2°C：①
150＜d≤200	Class 4	≥930	≥825	≥13	≥45	285~363	-12.2°C：①
200＜d≤240	Class 4	≥930	≥825	≥13	≥45	293~363
d≤75	Class 3	≥1000	≥895	≥12	≥40	293~363	-12.2°C：②
75＜d≤200	Class 3	≥1000	≥895	≥12	≥40	302~388	-12.2°C：②
200＜d≤240	Class 3	≥1000	≥895	≥12	≥40	311~388
d≤180	Class 2	≥1070	≥965	≥11	≥40	311~401	-12.2°C：②
180＜d≤240	Class 2	≥1070	≥965	≥11	≥40	321~415
d≤150	Class 1	≥1140	≥1035	≥10	≥35	321~415	-12.2°C：③
150＜d≤200	Class 1	≥1140	≥1035	≥10	≥35	331~429	-

GradeB24 Corresponding Standards(Same grade name, different standards)

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