Corundum flow steel bricks

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Table 1 Physical and Chemical Indicators of Corundum-flow Steel Brick
Item		Indicators
		JM-70	JM-80
ω（Al₂O₃）/%	≥	70.0	80.0
		±2
ω（Fe₂O₃）/%	≤	1.0	1.0
		±0.2
Refractoriness/℃	≥	1780	1780
		±10
Apparent Porosity/%	≤	28	28
		±2
Cold crushing strength/MPa	≥	25
		+7
Permanent linear change on heating (1500℃×2h)/%	Xmin~Xm₈x	-0.1~+0.4
Note: Funnel bricks and formwork bottom bricks are not subject to compressive strength testing.

5.2 The allowable deviation of the dimension and appearance requirements of the bricks should comply with the provisions of Table 2.

Table 1 Physical and Chemical Indicators of Corundum-flow Steel Brick (Corporate Indicators)
Item		Indicators
		JM-70	JM-80
ω（Al₂O₃）/%	≥	73.0	83.4
		±2
ω（Fe₂O₃）/%	≤	0.5	0.5
		±0.2
Refractoriness/℃	≥	1780	1780
		±10
Apparent Porosity/%	≤	22	22
		±2
Cold crushing strength/MPa	≥	40
		+7
Permanent linear change on heating (1500℃×2h)/%	Xmin~Xm₈x	-0.1~+0.4
Note: Funnel bricks and formwork bottom bricks are not subject to compressive strength testing.

Table 2 Allowable Deviation of Dimension and Appearance of Corundum-flow Steel Brick Unit: Millimeter
Item			Indicators
Allowable Deviation of Dimension	Diameter, height, or depth of inlaid mouth		±1
	Height and opening diameter of funnel brick		±2%
	Other dimension	≤150	±2
		151~300	±3
		>300	±1%
Relative deviation of wall thickness	Inlaid mouth		≤2
	Other parts		≤3
Slagging of retractory	Working surface		Not allowed
	Non-working surface	Area with depth ≤1mm	≤5%
		Depth >1mm	Not allowed
Length of unfilled corner and the damaged edge(a+b+c)、(e+f+g)	Depth of working surface		≤20
	Depth of non-working surface		≤40
Crack length	Width ≤0.10		Not limited
	Width 0.11~0.25	Depth of working surface	≤25
		Depth of non-working surface	≤50(Non-reticulate)
	Width>0.25		Not allowed
End plane incline	End face width or diameter	≤140	≤1
		>140	≤2

To respond to the spirit of our country's speech at the symposium of scientists, our company developed military and civilian special steel grades and overcame the foreign special steel technology blockade together with the Shenyang Institute of Metals, Chinese Academy of Sciences and the Institute of Special Steel Metallurgy of Northeastern University. At present, our company has contracted military special workshops of Dongbei Special Steel No. 1 and No. 2 Refining, Xining Special Steel, Baowu Steel and Ma’anshan Iron & Steel and so on. After use of our company's products, the quality of special steel products has been significantly improved. The cast special steel is widely used in military, aerospace, shipping, wind power, oil wells and other high-end industries. Under the increasingly severe international situation, our company has accelerated the research and development of refractory products, promoted the quality of our country's special steel, better served the steel industry, and promoted the development of special steel.

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