Difference between P275NH and P355NH steel plate

Dec 02, 2025 Leave a message

The main difference is that P275NH steel has a higher minimum yield strength of 275 N/mm², while P355NH steel has a higher minimum yield strength of 355 N/mm². Both are normalized fine-grain steels under the EN 10028-3 standard for pressure vessels, but P355NH is stronger.

info-850-508

P355NH Chemical Composition
Grade	The Element Max (%)
Grade	C	Si	Mn	P	S	Al(min)	N
P355NH	0.20	0.50	0.9-1.70	0.03	0.025		0.02
	Cr	Cu	Mo	Nb	Ni	Ti	V
	0.30	0.30	0.08	0.005	0.50	0.03	0.10

Carbon Equivalent: Ceq = 【C+Mn/6+(Cr+Mo+V)/5+(Ni+Cu)/15】%

P275NH Chemical Composition
Grade	The Element Max (%)
Grade	C	Si	Mn	P	S	Al(min)	N
P275NH	0.16	0.40	0.5-1.40	0.030	0.020		0.02
	Cr	Cu	Mo	Nb	Ni	Ti	V
	0.30	0.30	0.08	0.005	0.50	0.03	0.05

Carbon Equivalent: Ceq = 【C+Mn/6+(Cr+Mo+V)/5+(Ni+Cu)/15】%

Grade		P355NH Mechanical Property
Grade	Thickness	Yield	Tensilmie	Elongation	Impact Energy(KV J) min
P355NH	mm	Min Mpa	Mpa	Min %	-20°	0°	+20°
	≤ 16	355	490-630	22	47	55	63
	16> to ≤35	355	490-630	22	47	55	63
	35> to ≤50	345	490-630	22	47	55	63
	50> to ≤70	325	490-630	22	47	55	63
	70> to ≤100	315	470-610	21	47	55	63
	100> to ≤150	295	450-590	21	47	55	63

Grade		P275NH Mechanical Property
Grade	Thickness	Yield	Tensilmie	Elongation	Impact Energy(KV J) min
P275NH	mm	Min Mpa	Mpa	Min %	-20°	0°	+20°
	≤ 16	275	390-510	24	47	55	63
	16> to ≤35	275	390-510	24	47	55	63
	35> to ≤50	265	390-510	24	47	55	63
	50> to ≤70	255	390-510	24	47	55	63
	70> to ≤100	235	370-490	23	47	55	63
	100> to ≤150	235	350-470	23	47	55	63