Boiler Pressure Vessel Steel Type in China

Boiler Pressure Steel Types:

Low-Carbon Steel:

Low carbon steel is commonly used steel for the manufacture of boiler pressure components mainly include low carbon steel, low alloy structural steel, low alloy hot steel, austenitic stainless steel and martensitic steel. According to the profiles of these steel can be divided into sheet and pipe. Table 15-1a lists the chemical composition, mechanical properties and applicable ranges of commonly used boiler steels.

Table 15-1a listed in the low-carbon steel, according to the quality level is divided into ordinary carbon structural steel, high-quality carbon structural steel and special boiler steel.

Steel Type	Steel Grade	Standard	Chemical composition ，%										Tensile Strength σ_bMPa	Yield Strength σ_sMPa	elongation δ₅_%	Impact A_kv J	Strain aging impact toughness J	Application
			C	Si	Mn	V	Nb(W)	Mo	Cr	Ni(Ti)	P	S		Yield Strength σ_sMPa	elongation δ₅_%	Impact A_kv J	Strain aging impact toughness J	Application
											P	S		min				Working pressure MPa	Temperature（℃）
											Max			min				Working pressure MPa	Temperature（℃）
Low Carbon Steel Plate	Q235-A	GB700	0.14～0.22	0.30	0.30～0.65						0.045	0.050	375～460	185～235	21～26	27		≤1.0	When the steam pressure exceeds 0.1MPa, it should not contact with the flame
	Q235-B	GB700	0.12～0.20	0.30	0.30～0.70						0.045	0.045
	Q235-C	GB700	≤0.18	0.30	0.35～0.80						0.040	0.040
	Q235-D	GB700	≤0.17	0.30	0.35～0.80						0.035	0.035
	20g	GB713	≤0.20	0.15～0.30	0.50～0.90						0.035	0.035	380～530	185～245	22～26	27	29	≤5.9	≤450
	20R	GB6654	≤0.22	0.15～0.30	0.35～0.80						0.035	0.035	400～530	195～245	22～26	27		≤5.9	≤450
Low Carbon Steel Tube	20	GB3087	0.17～0.24	0.17～0.37	0.35～0.65				≤0.25	≤0.25	0.035	0.035	410	245	25			≤5.9	Heating surface tube≤480Header pipe≤430
Low Carbon Steel Tube	20G	GB5310	0.17～0.24	0.17～0.37	0.35～0.65						0.030	0.030	410～550	245	35	-	-	no limit	Heating surface tube≤480Header pipe≤430
Low Alloy Steel Plate	16Mng	GB713	≤0.20	0.20～0.55	1.20～1.60						0.035	0.030	440～655	245～345	18～21	27	29	≤5.9	≤400
Low Alloy Steel Plate	16MnR	GB713	≤0.20	0.20～0.60	1.20～1.60						0.035	0.035	450～655	265～345	18～21	27	-	≤5.9	≤400
Low Alloy Heat Resistant Steel	15CrMoG	GB5130	0.12～0.18	0.17～0.37	0.40～0.70			0.40～0.55	0.80～1.10		0.030	0.030	440～640	235	21	35		no limit	≤550
	12Cr1MoVG	GB5130	0.08～0.15	0.17～0.37	0.40～0.70	0.15～0.30		0.25～0.35	0.90～1.20		0.030	0.030	470～640	255	21	35		no limit	≤565
	12Cr2MoWVTiB	GB5130	0.08～0.15	0.45～0.75	0.45～0.65	0.28～0.42	0.30～0.55(W)	0.50～0.65	1.60～2.10	0.08～0.18(Ti)	0.030	0.030	540～735	345	18	35		no limit	≤600
	12Cr3MoVSiTiB	GB5130	0.09～0.15	0.60～0.90	0.50～0.80	0.25～0.35		1.00～1.20	2.50～3.00	0.22～0.38(Ti)	0.030	0.030	610～805	440	16	35		no limit	≤600
Austenitic Stainless Steel Pipe	1Cr18Ni9	GB5130	≤0.15	≤1.00	≤2.00				17.00～19.00	8.00～10.00	0.035	0.030	≥520	205	35			no limit	Endurance strength at 650 =63MPa
Austenitic Stainless Steel Pipe	1Cr19Ni11Nb	GB5130	0.04～0.10	≤1.00	≤2.00		Nb+Ti≥0.80～1.00		17.00～20.00	9.00～13.00	0.030	0.030	≥520	205	35			no limit	Endurance strength at 650 =63MPa

Which Q235A ~ D for the ordinary carbon structural steel, its name from the yield strength values, quality grade symbols and deoxidation method. "Q" for the yield strength of the first letter of the Chinese phonetic alphabet, followed by the yield strength of the value. Quality grade is divided into A, B, C, D four grades, from A to D steel quality level gradually increased.

20 steel for high-quality carbon structural steel, with the average carbon content of the number of points that the 20 steel (S, P) and non-metallic inclusions contained in high quality carbon structural steels with high quality carbon structural steels of 0.20% (20%), plasticity, toughness and processability Very good; special boiler steel is derived from the basis of carbon structural steel, steel and other high-quality carbon steel structure is similar to the plate is in the carbon content after the value of the lowercase Chinese alphabet letters "g" , 20g for the No. 20 special boiler plate; for the pipe in the carbon content after the value of the Chinese alphabet letters "G", 20G said 20 dedicated boiler steel pipe. This kind of steel in the chemical composition with the same grade of high quality carbon structural steel is basically the same, but the mechanical performance requirements are more stringent, especially the impact toughness has more stringent requirements, and requires a small sensitivity. This type of steel in the smelting should be a good deoxidation and place non-metallic inclusions, the organizational structure should be uniform, grain size hope to control in the 3 to 7, to minimize the sandwich, shrinkage, loose and pores and other defects. 20R is 20 container steel, chemical composition and 20g is very close to the mechanical properties are similar, when used to manufacture the boiler pressure components, should make up the strain aging impact test.

low-alloy structural steel

Low carbon steel has excellent plasticity, toughness and processing technology, but the strength is low, corrosion resistance is not strong enough. Through the ordinary low carbon steel, adding a small amount of alloying elements, the total amount of < 3%, you can get high strength, high toughness and good solderability and corrosion resistance of ordinary low-alloy structural steel. In this type of manganese is the main element, its content in about 1% to 1.6%. In addition to manganese can produce a strong solid solution strengthening effect, but also refine the ferrite grains, and make pearlite thinner, eliminating the grain boundary of the coarse flake carbide, thereby enhancing the strength and toughness of steel. In addition to the main plus elements, usually also add a small amount of vanadium, niobium, titanium and other auxiliary elements. These additional elements form fine carbides or nitrides in the steel, preventing the austenite grains from growing up during heating, facilitating the acquisition of fine ferrite grains, and also the effect of precipitation precipitation strengthening To further improve the strength and toughness of steel.

Steel Grade	Chemical Composition（%）
Steel Grade	C	Si	Mn	Ni	Cr	Mo	Nb	P	S
19Mn5	0.17～0.22	0.30～0.60	1.0～1.30	≤0.03	≤0.30	≤0.10		≤0.040	≤0.040
19Mn6	0.15～0.22	0.30～0.60	1.0～1.60	≤0.03	≤0.25	≤0.10		≤0.035	≤0.030
BHW35	≤0.15	0.10～0.50	1.0～1.60	0.6～1.0	0.2～0.40	0.2～0.40	0.005～0.020	≤0.025	≤0.025
A299	≤0.30	0.15～0.40	0.9～1.50	≤0.25	≤0.25	≤0.08		≤0.035	≤0.040

16Mng steel plate in the low-pressure boiler is widely used in China, has a good overall mechanical properties, welding performance, process performance and low temperature impact toughness. Medium temperature and low temperature mechanical properties are better than low carbon steel, corrosion resistance is also better than low carbon steel, but the gap is less sensitive than low carbon steel, in the presence of gaps, fatigue strength will be reduced, and easy to produce cracks. Table 16MnR, is a low-alloy container steel plate, used in the manufacture of boiler pressure components should be done when the strain aging impact test.

China in the large-scale boiler widely used 19Mn5, 19Mn6, BHW35 and A299 steel, the chemical composition in Table 15-1b. 19Mn5, 19Mn6 is the German production of carbon-manganese ordinary low-alloy steel, in the chemical composition of the harmful elements of sulfur and phosphorus control is very strict, the actual steel sulfur and phosphorus in the mass fraction of not more than 0.02%, in addition to smelting The vacuum degassing technology, greatly reducing the gas content in the steel. The steel has a good overall mechanical properties, welding performance and process performance, Table 15-1c, the temperature strength is better than 16Mng, Table 15-1d.

Steel Grade	σ_s（MPa）≥			σ_b（MPa）	δ₅（%）	ISO V notch impact power（0℃）J≥
Steel Grade	＞60～≤100（mm）	＞100～≤125（mm）	＞125～≤150（mm）	σ_b（MPa）	δ₅（%）	ISO V notch impact power（0℃）J≥
19Mn6	315	295	295	490～630	20	31
19Mn5	289	275	261	490～630	20	49
BHW35	390	380	375	570～740	18	31
A299	276			515～655	16	27

BHW35 (13MnNiMo54) is also produced in Germany, a multi-element content of low-alloy high-strength steel. The alloying elements of the steel are reasonable in design and stable in structure, and the strength of the steel is improved by the interaction of the multi-elements, and the comprehensive mechanical properties are also improved. Table 15-1c, Table 15-1e. The steel is generally used in normalizing and high temperature tempering state, the state of the tempering bainite plus ferrite, it is often referred to as low bainitic steel. A299 is a carbon-manganese-silicon series of US steel, in the chemical composition of the harmful elements of sulfur and phosphorus control is also very strict, the actual steel sulfur and phosphorus in the mass fraction of not more than 0.015%, lower than Table 15 -1b in the standard value, silicon, manganese mass fraction fluctuations are also small, to ensure a better solderability. The steel also has a good overall mechanical properties, a variety of hot and cold processing performance and medium temperature strength.

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