The quenched and tempered Q550D high strength steel

Q550D steel is a low-alloy high-strength steel plate, "Q" is the initial letter of the "yield" Chinese character for the yield strength of steel; "550" is the yield strength value, in MPa, D is the quality grade of D, Q550 is divided into Q550C, Q550D , Q550E three levels.

Q550D high strength steel implementation standard: GB/T 16270-2009, GB/T1591-2018

Q550D steel delivery status: quenching + tempering.

Q550D high strength steel mechanical properties:

Thickness	Mechanical properties
≤50	ReH(MPa)	≥550	When the yield is not obvious, use Rp0.2
	Rm(MPa)	640-820
	A(%)	≥16
	Impact temperature	-20
	Akv(J)	≥47	Longitudinal
	Remark	Transverse sampling for tensile test
>50~100	ReH(MPa)	≥530	When the yield is not obvious, use Rp0.2
	Rm(MPa)	640-820
	A(%)	≥16
	Impact temperature	-20
	Akv(J)	≥47	Longitudinal
	Remark	Transverse sampling for tensile test
>100~150	ReH(MPa)	≥490	When the yield is not obvious, use Rp0.2
	Rm(MPa)	590-770
	A(%)	≥16
	Impact temperature	-20
	Akv(J)	≥47	Longitudinal
	Remark	Transverse sampling for tensile test

Q550D steel chemical elements, Q550D melting analysis:

≤0.2

≤0.8

≤1.7

≤0.025

≤0.015

≤2

≤1.5

≤0.7

≤0.5

≤0.06

≤0.12

≤0.05

≤0.005

Composition remarks: At least one grain refining element among Nb, Ti, V, and Al is added to the steel, and the minimum amount of at least one element is 0.015 (Als for Al). Als can be replaced by Alt, where Alt≥0.018. Ceq = C+Mn/6+(Cr+Mo+V)/5+(Ni+Cu)/15