General Product Description

BSM590/SM490B/SM570 steel has high strength and good formablilty which is used in various industries. It can afford heavy load after common machining. Widely used in architecture, bridge construction, marine craft, railway locomotive heavy machine and other structural parts.

Mechanical Property

Grade	Tensile Test^a						180° Bend Test^b	V-notch Impact Test^c
	Yield Strength R_eH (MPa)		Tensile Strength R_m (MPa)	Elongation %				Test Temp. (℃)	Impact Energy KV₂ (J)
	≤16	＞16	Tensile Strength R_m (MPa)	L₀=50mm, b=25mm		L₀=200mm, b=40mm		Test Temp. (℃)	Impact Energy KV₂ (J)
SS330	≥205	≥195	330～430	≥26	≥21	≥26	D=1a	—	—
SS400	≥245	≥235	400～510	≥21	≥17	≥21	D=3a
SS490	≥285	≥275	490～610	≥19	≥15	≥19	D=4a
SS540	≥400	≥390	≥540	≥16	≥13	≥17	D=4a
SM400A	≥245	≥235	400～510	≥23	≥18	≥22	D=2a	—	—
SM400B								0	≥27
SM400C								0	≥47
SM490A	≥325	≥315	490～610	≥22	≥17	≥21	D=3a	—	—
SM490B								0	≥27
SM490C								0	≥47
SM490YA	≥365	≥355	490～610	≥19	≥15	≥19	D=3a	—	—
SM490YB	≥365	≥355	490～610	≥19	≥15	≥19	D=3a	0	≥27
SM520B	≥365	≥355	520～640	≥19	≥15	≥19	D=3a	0	≥27
SM520C	≥365	≥355	520～640	≥19	≥15	≥19	D=3a	0	≥47
SM570	≥460	—	570～720	≥19^d		—	D=3a	-5	≥47
BSM590	≥450	—	590～710	≥20^d		—	D=2a	-5	≥47

a Transverse test specimens are used for the tensile test. When the yield phenomenon is not obvious, R_p0.2 shall be used.
b Transverse test specimens are used for the bend test. Bend specimen width b ≥ 20 mm; for referee tests b = 20 mm. D—mandrel diameter; a—specimen thickness.
c Longitudinal test specimens are used for the impact test.
d Tensile specimen L₀ = 50 mm, b = 25 mm, type P17 specimen per GB/T 228.1—2021.

Chemical Composition

Grade	C	Si	Mn	P	S	Others^a
SM400A	≤0.23	≤0.35	≥2.5×C^d	≤0.025	≤0.020	—
SM400B	≤0.20		0.60～1.50
SM400C	≤0.18		0.60～1.50
SM490A	≤0.20	≤0.55	≤1.65			Ceq^b≤0.38
SM490B、SM490C	≤0.18					Ceq^b≤0.38
SM490YA、SM490YB	≤0.20					Ceq^b≤0.38
SM520B、SM520C	≤0.20					Ceq^b≤0.40
SM570	≤0.18	≤1.70				Ceq^b≤0.44
BSM590	≤0.16	≤0.55	≤2.00	≤0.025	≤0.020	Ceq^b≤0.45
B590GJA、B590GJB	≤0.15	≤0.55	≤1.60	≤0.025	≤0.020	Nb+V≤0.15 Ni≤0.50
B520JJ	≤0.20	≤0.55	≤1.60	≤0.025	≤0.020	Cu：0.20～0.45
B750GJ	≤0.20	≤0.55	≤1.80	≤0.025	≤0.020	Cr≤0.50、Mo≤0.50、 Nb+V+Ti≤0.22
StE255	≤0.18	≤0.40	0.50～1.30	≤0.025	≤0.020	Alt^c≥0.020
StE285	≤0.18	≤0.40	0.50～1.50			N≤0.015
StE355	≤0.20	≤0.50	0.90～1.65			Nb+V+Ti≤0.22

a Other alloying elements may be added as required.
b Ceq = C + Mn/6 + Si/24 + Ni/40 + Cr/5 + Mo/4 + V/14
c Where other sufficient nitrogen-binding elements are present, the minimum specified Alt content does not apply.
d C content is determined by actual heat analysis.