High-strength structural steel standard GB/T1591

GB/T1591 standard specifies low alloy high strength structural steel. 
GB/T1591 steel grades: Q295, Q345C,Q390C, Q420,Q460D
Chemical composition in table 1

Grade	Quality level	Chemical composition (%)
		C≤	Mn	Si ≤	P ≤	S ≤	V	Nb	Ti	Al≥	Cr≤	Ni≤
Q295	A	O.16	0.8	0.55	0.045	0.045	0.02	0.015	O.02
	B		～1.50		0.04	O.040	～O.15	～O.060	～0.20
Q345	A	O.20	1	0.55	0.045	O.045	O.02～O.15	O.015～0.06	O.02～O.20
	B		～1.60		O.040	O.040
	C				0.035	0.035				O.015
	D	O.18			0.03	O.030				O.015
	E				0.025	O.025				O.015
Q390	A	O.20	1	O.55	0.045	0.045	O.02～O.20	O.015～0.06	O.02～O.20		O.30	0.7
	B		～1.60		O.040	O.040					O.30	O.70
	C				O.035	O.035				O.015	0.3	O.70
	D				O.030	0.03				0.015	O.30	0.7
	E				0.025	O.025				O.015	O.30	0.7
Q420	A	O.20	1	O.55	O.045	O.045	O.02～O.20	O.015～0.06	O.02～O.20		O.40	O.70
	B		～		0.04	O.040					O.40	O.70
	C		1.7		O.035	O.035				0.015	0.4	O.70
	D				O.030	0.03				0.015	O.40	O.70
	E				0.025	0.025				0.015	O.40	O.70
Q460	C	O.20	1		0.035	0.035	O.02～O.20	O.015～0.06	O.02～O.20	O.015	O.70	0.7
	D		～	O.55	O.030	0.03				0.015	0.7	0.7
	E		1.7		0.025	O.025				O.015	0.7	0.7

Mechanical properties are shown in Table 2

Grade	Quality level	Yield point ós/Mpa ≥				Tensile strength ób/MPa	Elongation δ5 (%) ≥	Impact absorption work Akv (longitudinal)
		Thickness (diameter, side length) / mm						／J    ≥
		≤16	>16～35	>35～50	>50～100			+20℃	O℃	-20℃	-40℃
Q295	A	295	275	255	235	390～570	23
	B						23	34
Q345	A	345	325	295	275	470～630	21
	B						2l	34
	C						22		34
	D						22			34
	E						22				27
Q390	A	390	370	350	330	490～650	19
	B						19	34
	C						20		34
	D						20			34
	E						20				27
Q420	A	420	400	380	360	520	18
	B					～680	18	34
	C						19		34
	D						19			34
	E						19				27
Q460	C	460	440	420	400	550	17		34
	D					～720	17			34
	E						17				27

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