Astm A321 Hot Rolled Steel Tube , Quenched Tempered Carbon Steel Bar 6.35 - 241.3mm

 

This specification covers hot-rolled, quenched, and tem-pered carbon steel bars, of the following sections and sizeranges:
1)Rounds, '% to 9/ in. (6.35 to 241.3 mm) incl, indiameter.
2)Squares, '/4 to 5/ in. (6.35 to 139.7 mm) incl,between parallel surfaces.
3)Hexagons, '/4 in. (6.35 mm) and over betweenparallel surfaces.
The values stated in inch-pound units are to be regardedas the standard. The values given in parentheses are forinformation only. .

 

2.Manufacture

 

1)Melting Practice The steel shall be made by one ormore of the following primary processes: open-hearth, basic-oxygen, or electric-furnace. The primary melting may incor-porate separate degassing or refining and may be followed bysecondary melting using electroslag remelting or vacuum arcremelting. Where secondary melting is employed, the heatshall be defined as all of the ingots remelted from a singleprimary heat.

 

2)Discard -A sufficient discard shall be made (from eachingot, when ingot cast) to secure freedom from injurious pipingand undue segregation.

 

3)Heat Treatment:

Cooling -Immediately after rolling, the bars shall beallowed to cool to a temperature below the critical range undersuitable conditions to prevent injury by too rapid cooling.

Quenching and Tempering -The material shall beuniformly heated to the austenitizing temperature, soaked for asufficient length of time to produce the desired change instructure (a group thus heated being known as a quenchingcharge), and quenched in some medium under substantiallyuniform conditions for each quenching charge. The materialshall then be uniformly reheated to the proper temperature fortempering (a group thus reheated being known as a temperingcharge), and allowed to cool uniformly. The temperatureselected for tempering shall not be less than 800F (427C).

Stress Relieving -When it is desirable to minimizeinternal stresses introduced by straightening, the purchasermay specify a stress relief anneal as a final operation.

 

3.Mechanical Properties

 

1)Tensile Properties -The material, after final heat treat-ment and straightening, shall conform to the requirements as totensile properties specified in Table 2.

 

2)Test Specimens: .

Test specimens shall be prepared for testing from thematerial in the quenched and tempered condition.

Specimens shall be taken longitudinally and may betested in full thickness or section, or they may be machined tothe dimensions shown in Figs.4 or Figs.6 of Test Methods andDefinitions A 370. If test specimens are selected conforming tothe dimensions of Fig.6 for sizes 1'/ in. (38.1 mm) and largerin diameter or distance between parallel faces, they shall bemachined from a position midway between the center and the surface of the bar. If test specimens are selected conforming tothe dimensions of Fig.6 for sizes under 1'/h in. in diameter ordistance between parallel faces, they shall be machined fromthe center of the bar.

3)Number of Tests One tension test shall be made fromeach tempering or stress-relieving charge. If more than onequenching charge is represented, one tension test shall be madefrom each quenching charge. If more than one heat is repre-sented in a quenching charge, one tension test shall be madefrom each heat and size. For continuous type of treatment, onetension test shall be made for each 25 tons (23 Mg) of each heator size.

4)Test Methods- Tension tests shall be made in accor-dance with Test Methods and Definitions A 370. The yieldpoint shall be determined by the drop of the beam or halt in thegage of the testing machine, or by the use of dividers, ascovered in Section 12 of Test Methods and Definitions A 370.

 

Outside diameter and wall thickness allow deviation mm

sort code	Manufacturing method	Steel tube size		Allowable deviation
WHR (WHEX)	Hot rolled(extruded)steel tube	OD	all	±1%Dor±0.50(choose the bigger)
		WT	≤20	-15% +0.45 -10%S or –0.30 (choose the bigger)
			＞20	±10%S
WHE	Heat expand steel tube	OD	all	±1%D
		WT	all	±15%S
WCD (WCR)	Cold drawn(rolled) steel tube	OD	≤30	±0.20
			30＜D≤50	±0.30
			＞50	±0.8%D
		WT	1.5≤S≤3	+12.5% -10% S
			＞3	±10%S

 

Bending of steel tube per meter

OD/mm	Bending per meter(mm/m)
≤15	≤1.5
＞15~30	≤2.0
＞30 or D≥351	≤3.0