1、Standard Specification for Steel Bars, Carbon, Hot-Wrought, Special Quality, Mechanical Properties AASHTO Designation: M 255M/M 255-05 (2013) ASTM Designation: A675/A675M-031American Association of State Highway and Transportation Officials 444 North Capitol Street N.W., Suite 249 Washington, D.C. 2
2、0001TS-4f M 255M/M 255-1 AASHTO Standard Specification for Steel Bars, Carbon, Hot-Wrought, Special Quality, Mechanical Properties AASHTO Designation: M 255M/M 255-05 (2013) ASTM Designation: A675/A675M-0311. SCOPE 1.1. This specification covers hot-wrought, special quality, carbon steel bars and ba
3、r size shapes produced to mechanical property requirements and intended for general constructional applications. 1.2. The bars are available in nine strength grades designated 310, 345, 380, 415, 450, 485, 515, 550, and 620 45, 50, 55, 60, 65, 70, 75, 80, and 90 corresponding to the minimum ultimate
4、 tensile strength in MPa ksi. The chemical composition is selected by the manufacturer to develop the required mechanical properties. 1.3. Hot-wrought, special quality, carbon steel bars subject to mechanical property requirements are hot wrought in straight lengths only. Sections and sizes availabl
5、e are covered in ASTM A29/A29M. 1.4. Some applications may require one or more of the available designations shown under Supplementary Requirements. Note 1Merchant quality, hot-wrought carbon steel bars subject to mechanical property requirements are covered in M 227M/M 227. 1.5. This specification
6、is applicable to orders in either SI units (as M 255M) or inch-pound units (as M 255). SI units and inch-pound units are not necessarily equivalent. Inch-pound units are shown in brackets in the text for clarity, but they are the applicable values when the material is ordered to M 255. 2. REFERENCED
7、 DOCUMENTS 2.1. AASHTO Standards: M 227M/M 227, Steel Bars, Carbon, Merchant Quality, Mechanical Properties T 244, Mechanical Testing of Steel Products 2.2. ASTM Standards: A29/A29M, Standard Specification for General Requirements for Steel Bars, Carbon and Alloy, Hot-Wrought E290, Standard Test Met
8、hods for Bend Testing of Material for Ductility 2015 by the American Association of State Highway and Transportation Officials.All rights reserved. Duplication is a violation of applicable law.TS-4f M 255M/M 255-2 AASHTO 3. TERMINOLOGY 3.1. Definition: 3.1.1. special qualityspecial quality bars are
9、used when end use, method of fabrication, or subsequent processing treatment requires quality characteristics not available in merchant quality. Typical applications involve bending or machining for general constructional uses. Some end uses or fabricating procedures can necessitate one or more requ
10、irements, which are described in the Supplementary Requirements. 4. ORDERING INFORMATION 4.1. Orders for material under this specification should include the following information: 4.1.1. Quantity (mass or number of pieces); 4.1.2. Name of material (hot-wrought special quality bars); 4.1.3. Dimensio
11、ns, including length; 4.1.4. Cross section (round, square, hexagon, equal leg angle, etc.); 4.1.5. AASHTO designation and date of issue; 4.1.6. Grade designation (Table 2); 4.1.7. Leaded steel (if required) (Section 7.2); 4.1.8. Copper bearing steel (if required) (Section 7.3); 4.1.9. Test report (i
12、f required) (Section 10); 4.1.10. Supplementary Requirements or special requirements (if required); and 4.1.11. Application and processing. Note 2A typical ordering description is as follows: 5000 kg 10,000 lb Hot-Wrought Special Quality Carbon Steel Bars, 25-mm diameter 3 m 1 in. 10 ft Round, M 255
13、M/M 255, Grade 345 50, Copper Bearing, Test Report Required, S3 Special Straightness, Boiler Supports. 5. GENERAL REQUIREMENTS 5.1. Material furnished under this specification shall conform to the applicable requirements for the current edition of ASTM A29/A29M. 6. MATERIALS AND MANUFACTURE 6.1. Mel
14、ting PracticeThe steel shall be made by one or more of the following primary processes: open-hearth, basic oxygen, or electric furnace. The primary melting may incorporate separate degassing or refining and may be followed by secondary melting using electroslag remelting or vacuum-arc remelting. Whe
15、re secondary melting is employed, the heat shall be defined as all of the ingots remelted from a single primary heat. 2015 by the American Association of State Highway and Transportation Officials.All rights reserved. Duplication is a violation of applicable law.TS-4f M 255M/M 255-3 AASHTO 6.2. Deox
16、idation: 6.2.1. Unless otherwise specified, the steel shall be rimmed, capped, semi-killed, or killed at the producers option. 6.2.2. When required, the purchaser may specify the required deoxidation practice, dependent upon strength grade specified, purchasers methods of fabrication, and end-use re
17、quirements. Killed steels can be produced to coarse or fine austenitic grain size (see Supplementary Requirement S1). 6.3. ConditionUnless otherwise specified, the bars shall be furnished as rolled and not pickled, blast cleaned, or oiled. At the producers option, bars may be cleaned for inspection.
18、 7. CHEMICAL COMPOSITION 7.1. The steel shall conform to the chemical requirements specified in Table 1. 7.2. Leaded SteelWhen required, lead may be specified as an added element. When lead is specified as an added element, a range from 0.15 to 0.35 percent inclusive shall be furnished. Such a steel
19、 is identified by adding the letter “L” after the grade designation, for example, “415L 60L.” 7.3. Copper-Bearing SteelWhen required, copper may be specified as an added element. Copper-bearing steel is identified by stating “copper-bearing” on the purchase order. 7.4. When tension tests are waived
20、in accordance with Section 8.1.1.2, chemistry consistent with the mechanical properties desired shall be applied. 8. MECHANICAL PROPERTIES 8.1. Tension Tests: Table 1Chemical Requirements (Heat Analysis) Element Composition, % Phosphorus, max 0.040 Sulfur, max 0.050 Copper, when copper steel is spec
21、ified, min 0.20 Lead a a When required, lead may be specified as an added element. See Section 7.2. 8.1.1. Requirements: 8.1.1.1. The material as represented by the test specimen shall conform to the applicable requirements in Table 2. 2015 by the American Association of State Highway and Transporta
22、tion Officials.All rights reserved. Duplication is a violation of applicable law.TS-4f M 255M/M 255-4 AASHTO Table 2Tensile Requirements Grade DesignationcTensile Strength Yield Point, MinaElongation, Min %bMPa ksi MPa ksi 200-mm 8-in. Gauge Length 50-mm 2-in. Gauge Length 310 45 310 to 380 45 to 55
23、 155 22.5 27 33 345 50 345 to 415 50 to 60 170 25 25 30 380 55 380 to 450 55 to 65 190 27.5 23 26 415 60 415 to 495 60 to 72 205 30 21 22 450 65 450 to 530 65 to 77 225 32.5 17 20 485 70 485 to 585 70 to 85 240 35 14 18 515 75 515 to 620 75 to 90 260 37.5 14 18 550 80 550 min 80 min 275 40 13 17 620
24、 90 620 min 90 min 380 55 10 14 aWhen the tension test does not show a yield point (drop of the beam, halt of the pointer, or sharp-kneed stressstrain diagram), yield strength shall be determined by either 0.5 percent extension under load or 0.2 percent offset. The minimum MPa ksi requirement does n
25、ot change. The test report, if required, shall show yield strength. bSee Sections 8.1.1.3 through 8.1.1.6 for deduction in elongation due to section size. cWhen lead is required, add the letter “L” after the grade designation; for example, “310L 45L.” 8.1.1.2. Shapes less than 645 mm21 in.2 in cross
26、 section and bars (other than flats) less than 12.5 mm 1/2in. in thickness or diameter need not be subject to tension tests by the manufacturer. 8.1.1.3. For material greater than 20 mm 3/4in. in thickness or diameter, a deduction of 0.25 percent from the percentage of elongation in 200 mm 8 in. spe
27、cified in Table 2 shall be made for each increase of 0.8 mm 1/32in. in the specified thickness or diameter above 20 mm 3/4in. 8.1.1.4. For material under 8 mm 5/16in. in thickness or diameter, a deduction of 2.00 percent from the percentage of elongation in 200 mm 8 in. specified in Table 2 shall be
28、 made for each decrease of 0.8 mm 1/32in. in the specified thickness or diameter below 8 mm 5/16in. 8.1.1.5. For grades 310, 345, 380, 415, and 450 45, 50, 55, 60, and 65 for material over 50 mm 2 in. in thickness or diameter, a deduction of 1.00 percent from the percentage of elongation in 50 mm 2
29、in. specified in Table 2 shall be made for each 25 mm 1 in. of specified thickness or diameter or fraction thereof over 50 mm 2 in. in thickness in diameter. 8.1.1.6. For grades 485, 515, 550, and 620 70, 75, 80, and 90 for material over 50 mm 2 in. in thickness or diameter, a deduction of 1.00 perc
30、ent from the percentage of elongation in 50 mm 2 in. specified in Table 2 shall be made for each 25 mm 1 in. of specified thickness or diameter, or fraction thereof, over 50 mm 2 in. in diameter or thickness, to a maximum deduction of 3 percent. 8.1.2. Test Specimens: 8.1.2.1. Test specimens shall b
31、e prepared for testing from the material in its as-rolled condition unless otherwise specified (see Supplementary Requirements). The tension specimen may be aged as described in T 244. 8.1.2.2. Test specimens shall be taken longitudinally and may be tested in full thickness or section, or they may b
32、e machined to the dimensions shown in Figures 4 or 5 of T 244. If test specimens are selected conforming to the dimensions of Figure 5, they shall be machined from a position midway between the center and the surface of the bar. 8.1.2.3. Test specimens for shapes and flats may be machined to the for
33、m and dimensions shown in Figure 4 of T 244 or with both edges parallel. Test specimens for material greater than 40 mm 11/2in. in thickness or diameter may be machined to a thickness or diameter of at least 20 mm 2015 by the American Association of State Highway and Transportation Officials.All rig
34、hts reserved. Duplication is a violation of applicable law.TS-4f M 255M/M 255-5 AASHTO 3/4in. for a length of at least 230 mm 9 in., or they may conform to the dimensions shown in Figure 5 of T 244. 8.1.3. Number of TestsTwo tension tests shall be made from each heat, unless the finished material fr
35、om a heat is less than 45 Mg 50 tons, when one tension test will be sufficient. However, for material 50 mm 2 in. and under in thickness, when the material from one heat differs 9.5 mm 3/8in. or more in thickness, one tension test shall be made from both the thickest and the thinnest material rolled
36、 (larger than the sizes in Section 8.1.1.2) regardless of the mass represented. For material more than 50 mm 2 in. thick, when the material from heat differs 25 mm 1 in. or more in thickness, one tension test shall be made from both the thickest and the thinnest material rolled that is more than 50
37、mm 2 in. thick regardless of the mass represented. 8.1.4. Test MethodTension tests shall be made in accordance with T 244 using the applicable method for determining yield point. 8.2. Bend Tests: 8.2.1. Requirements: 8.2.1.1. Bend requirements apply only to flat bars (all sizes), bars other than fla
38、ts less than 12.5 mm 1/2in. in thickness or diameter, and shapes less than 645 mm21 in.2 in cross section. When bend tests are required for other sizes, Supplementary Requirement S6 must be specified. 8.2.1.2. The bend test specimen shall stand being bent at room temperature through 180 degrees with
39、out cracking on the outside of the bent portion to an inside diameter which shall have the relation to the thickness or diameter of the specimen as given in Table 3. Table 3Bend Requirements Ratio of Bend Diameter to Thickness of Specimen for Thickness or Diameter of Bar, mm in. Grade Designation 20
40、 3/4 and Under Over 20 3/4 to 25 1, incl Over 25 1 to 40 11/2, incl Over 40 11/2 to 50 2, incl Over 50 2 to 75 3, incl Over 75 3 to 125 5, incl Over 125 5 310 45 Flat Flat 1/21 1 2 3 345 50 Flat 1/21 11/221/23 31/2380 55 1/21 11/22 21/23 31/2415 60 1/21 11/221/23 31/24 450 65 1 11/22 3 31/24 5 485 7
41、0 11/22 21/23 31/24 5 515 75 2 2 3 31/24 41/26 550 80 2 21/23 31/24 41/26 620 90aaBend requirements are not required for Grade 620 90 but may be specified by agreement between purchaser and manufacturer. (See Supplementary Requirement S6.) 8.2.2. Test Specimens: 8.2.2.1. Bend-test specimens for mate
42、rial 40 mm 11/2in. and under in diameter or thickness may be the full thickness of the section. For flat bars more than 50 mm 2 in. in width, the width may be reduced by milling to 40 mm 11/2in. 8.2.2.2. Bend-test specimens for material greater than 40 mm 11/2in. in diameter or thickness may be mach
43、ined to a thickness or diameter of at least 20 mm 3/4in. or to 25 by 12.5 mm 1 by 1/2in. in section. Machined sides of bend-test specimens may have the corners rounded to a radius of not 2015 by the American Association of State Highway and Transportation Officials.All rights reserved. Duplication i
44、s a violation of applicable law.TS-4f M 255M/M 255-6 AASHTO more than 1.6 mm 1/16in. for material 50 mm 2 in. and under in thickness and not more than 3.2 mm 1/8in. in radius for material greater than 50 mm 2 in. in thickness. 8.2.3. Number of TestsWhen subject to bend test, two bend tests shall be
45、made from each heat, unless the finished material from a heat is less than 45 Mg 50 tons, when one bend test will be sufficient. However, for material 50 mm 2 in. and under in thickness, when the material from one heat differs 9.5 mm 3/8in. or more in thickness, one bend test shall be made from both
46、 the thickest and the thinnest material rolled regardless of the mass represented. For material more than 50 mm 2 in. thick, when the material from one heat differs 25 mm 1 in. or more in thickness, one bend test shall be made from both the thickest and the thinnest material rolled that is more than
47、 50 mm 2 in. thick regardless of the mass represented. 8.2.4. Test MethodsBend tests shall be made in accordance with ASTM E290. 9. WORKMANSHIP, FINISH, AND APPEARANCE 9.1. Bars shall be free of visible pipe, undue segregation, and injurious surface imperfections. 9.2. Surface FinishThe bars shall h
48、ave a commercial hot-wrought finish obtained by conventional hot rolling. See Section 6.3 for producers descaling option. 10. CERTIFICATION 10.1. When specified by the purchaser, a manufacturers certification that the material was manufactured and tested in accordance with this specification togethe
49、r with a report of the heat analysis, tensile requirements, and bend-test (if applicable) results shall be furnished. Only one test need be reported when the amount of material from a heat in a shipment is less than 9 Mg 10 tons and when the thickness variations described in Sections 8.1.3 and 8.2.3 are not exceeded. The report sha
