ASTM A350/A350M-2024 is a standard published by the American Society for Testing and Materials (ASTM), which applies to forged carbon and low-alloy steel piping components used for low-temperature service. These components typically require toughness testing to ensure performance in low-temperature environments.
Standard Specification for Carbon Steel and Low-Alloy Steel Forgings, Requiring Notch Toughness Testing for Piping Componets
This specification covers several grades of carbon and low-alloy steel forged or ring-rolled flanges, forged fittings, and valves intended primarily for low-temperature service and requiring notch toughness testing. They are made to specified dimensions or to dimensional standards such as the ASME and API Specifications referenced in Section 2. Although this specification covers some piping components machined from rolled bar and seamless tubular materials (see 5.3.3), it does not cover raw material produced in these product forms.
No limitation on size is intended beyond the ability of the manufacturer to obtain the specified requirements. However, Class 3 of Grade LF787 is only available in the quenched and precipitation heat-treated condition.
Supplementary requirements are provided for use when additional testing or inspection is desired. These shall apply when specified by the purchaser.
ASTM A350/A350M Chemical Requirement
| Element | Composition,wt.% | ||||||
| Grade LF1 | Grade LF2 | Grade LF3 | Grade LF5 | Grade LF6 | Grade LF9 | Grade LF787 | |
| Carbon,max | 0.3 | 0.3 | 0.2 | 0.3 | 0.22 | 0.2 | 0.07 |
| Manganese | 0.60-1.35 | 0.60-1.35 | 0.90 max | 0.60-1.35 | 1.15-1.50 | 0.40-1.06 | 0.40-0.70 |
| Phosphorus, max | 0.035 | 0.035 | 0.035 | 0.035 | 0.025 | 0.035 | 0.025 |
| Sulfur,max | 0.04 | 0.04 | 0.04 | 0.04 | 0.025 | 0.04 | 0.025 |
| Silicon【A】 | 0.15-0.30 | 0.15-0.30 | 0.20-0.35 | 0.20-0.35 | 0.15-0.30 | … | 0.40 max |
| Nickel | 0.40 max【B】 | 0.40 max【B】 | 3.3-3.7 | 1.0-2.0 | 0.40 max【B】 | 1.60-2.24 | 0.70-1.00 |
| Chromium | 0.30 max【B】,【C】 | 0.30 max,【B】,【C】 | 0.30 max【C】 | 0.30 max【C】 | 0.30 max【B】,【C】 | 0.30 max【C】 | 0.60-0.90 |
| Molybdenum | 0.12 max【B】,【C】 | 0.12 max【B】,【C】 | 0.12 max【C】 | 0.12 max【C】 | 0.12 max【B】,【C】 | 0.12 max【C】 | 0.15-0.25 |
| Copper | 0.40 max【B】 | 0.40 max【B】 | 0.40 max | 0.40 max | 0.40 max【B】 | 0.75-1.25 | 1.00-1.30 |
| Niobium【E】 | 0.02 max【D】 | 002 max【D】 | 0.02 max | 0.02 max | 0.02 max | 0.02 max | 0.02 min |
| Vanadium | 0.08 max | 0.08 max | 0.03 max | 0.03 max | 0.04-0.11 | 0.03 max | 0.03 max |
| Nitrogen | ··· | ··· | ··· | ··· | 0.01-0.030 | ··· | ··· |
| 【A】When vacuum carbon-deoxidation is required by Supplementary Requirement S3,the siicon content shall be 0.12%maximum. 【B】The sum of copper,nickel,chromium,vanadium and molybdenum shall not exceed 1.00%on heat analysis. 【C】The sum of chromium and molybdenum shall not exceed 0.32%on heat analysis. 【D】By agreement,the limit for niobium (columbium)may be increased up to 0.05%on heat analysis and 0.06%on product analysis. 【E】Niobium and columbium are interchangeable names for the same element and both names are acceptable for use in A01.22 specifications. | |||||||
ASTM A350/A350M Tensile Requirements
| TABLE 2 Tensile Properties at Room Temperature【A】 | ||||||||
| Grades | ||||||||
| LF1 and LF5 Class 1 | LF2 Classes 1 and 2 | LF3 Classes 1 and 2 LF5 Class 2 | LF6 | LF9 | LF787 | |||
| Class 1 | Classes 2 and 3 | Class 2 | Class 3 | |||||
| Tensile strength,ksi [MPa] | 60-85 [415-585] | 70-95 [485-655] | 70-95 [485-655] | 66-91 [455-630] | 75-100 [515-690] | 63-88 [435-605] | 65-85 [450-585] | 75-95 [515-655] |
| Yield strength,min,ksi [MPa]【B】 | 30 [205] | 36 [250] | 37.5 [260] | 52 [360] | 60 [415] | 46 [315] | 55 [380] | 65 [450] |
| Elongation: Standard round specimen,or small proportional specimen, min% in 4D gauge length | 25 | 22 | 22 | 22 | 20 | 25 | 20 | 20 |
| Strip specimen for wallthickness 5/16 in.[7.94 mm]and over and for all small sizes tested in full section;min % in 2 in. [50 mm] | 28 | 30 | 30 | 30 | 28 | 28 | 28 | 28 |
| Equation for calculating min elongation for strip specimens thinner than 5/16 in.[7.94 mm] min%in 2 in.[50 mm] t=actual thickness in inches | 48t+13 | 48t+15 | 48t+15 | 48t+15 | 48t+13 | 48t+13 | 48t+13 | 48t+13 |
| Reduction of area,min,%【C】 | 38 | 30 | 35 | 40 | 40 | 38 | 45 | 45 |
| 【A】 See 7.3 for hardness tests. 【B】 Determined by either the 0.2%offset method or the 0.5%extension under load method. 【C】For round specimens only. | ||||||||
ASTM A350/A350M Charpy Impact Test
| TABLE 3 Charpy V-Notch Energy Requirements for Standard Size [10 by 10 mm]Specimens | ||
| Grade | Minimum Impact Energy Required for Average of Each Set of Three Specimens,ft.Ibf [J] | Minimum Impact Energy Permitted for One Specimen only of a Set,ft · Ibf [J] |
| LF1 and LF9 | 13 [18] | 10 [14] |
| LF2,Class 1 | 15 [20] | 12 [16] |
| LF3,Class 1 | 15 [20] | 12 [16] |
| LF5 Class 1 and 2 | 15 [20] | 12 [16] |
| LF787 Classes 2 and 3 | 15 [20] | 12 [16] |
| LF6,Class 1 | 15[20] | 12 [16] |
| LF2,Class 2 | 20 [27] | 15 [20] |
| LF3,Class 2 | 20 [27] | 15 [20] |
| LF6,Classes 2 and 3 | 20 [27] | 15 [20] |
| TABLE 4 Standard Impact Test Temperature for Standard Size [10 by 10 mm]Specimens | |
| Grade | Test Temperature,F[C] |
| LF1 | -20 [-29] |
| LF2 Class 1 | -50 [-46] |
| LF2 Class 2 | -0 [-18] |
| LF3,Classes 1 and 2 | -150 [-101] |
| LF5,Classes 1 and 2 | -75[-59] |
| LF6,Classes 1 and 2 | -60 [-51] |
| LF6,Class 3 | 0[-18] |
| LF9 | -100 [-73] |
| LF787,Class 2 | -75[-59] |
| LF787 Class 3 | -100 [-73] |
For more information about ASTM A350/A350M, please contact SSM. We provide product and technical service support.
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