Introduction to ASTM B424 Standard:
ASTM B424 is a standard specification established by the American Society for Testing and Materials (ASTM) that outlines the requirements for nickel-iron-chromium-molybdenum-copper alloys (UNS N08825, N08221, and N06845) plate, sheet, and strip.
Included Grades and Chemical Composition:
ASTM B424 covers several grades of nickel-iron-chromium-molybdenum-copper alloys, each with its unique chemical composition:
- 1. UNS N08825 (Incoloy 825, 2.4858): Comprises nickel, iron, chromium, molybdenum, and copper, with additions of titanium and niobium.
- 2. UNS N08221: This grade typically consists of nickel, iron, chromium, molybdenum, and copper, with controlled levels of carbon, manganese, and silicon.
- 3. UNS N06845: Contains nickel, iron, chromium, molybdenum, copper, and titanium, with additions of aluminum and tantalum.
ASTM B424 Chemical RequirementsA
| Element | UNS N08825 | UNS N08221 | UNS N06845 | |||||
| Nickel | 38.0 to 46.0 | 39.0 to 46.0 | 44.0 to 50.0 | |||||
| Chromium | 19.5 to 23.5 | 20.0 to 22.0 | 20.0 to 25.0 | |||||
| Iron | 22.0 minB | BalanceB | RemainderB | |||||
| Manganese | 1.0 | 1.0 | 0.5 | |||||
| Carbon | 0.05 | 0.025 | 0.05 | |||||
| Copper | 1.5 to 3.0 | 1.5 to 3.0 | 2.0 to 4.0 | |||||
| Silicon | 0.5 | 0.5 | 0.5 | |||||
| Sulfur | 0.03 | 0.03 | 0.010 | |||||
| Aluminum | 0.2 | 0.2 | ... | |||||
| Titanium | 0.6 to 1.2 | 0.6 to 1.0 | ... | |||||
| Molybdenum | 2.5 to 3.5 | 5.0 to 6.5 | 5.0 to 7.0 | |||||
| Tungsten | ... | ... | 2.0 to 5.0 | |||||
A Maximum unless range or minimum is given. Where ellipses (...) appear in this table, there is no requirement and analysis for the element need not be determined or reported.
B Element shall be determined arithmetically by difference.
Mechanical Properties:
The mechanical properties of ASME SB 424 alloys vary depending on factors such as grade, thickness, and heat treatment. Common mechanical properties include tensile strength, yield strength, elongation, and hardness.
| Alloy | Condition | Tensile Strength, min,ksi (MPa) |
Yield StrengthA (0.2 %Offset) min,ksi (MPa) |
Elongation in 2 in.or 50 mm or 4 D),min,% |
||||
| Hot-Rolled Plate: | ||||||||
| UNS N08825 | annealed | 85(586) | 35 (241) | 30 | ||||
| UNS N08221 | annealed | 79(544) | 34 (235) | 30 | ||||
| UNS N06845 | annealed | 100(690 | 40(276) | 30 | ||||
| Cold-Rolled Plate: | ||||||||
| UNS N08825 | annealed | 85(586 | 35 (241) | 30 | ||||
| UNS N08221 | annealed | 79(544) | 34 (235) | 30 | ||||
| UNS N06845 | annealed | 100(690 | 40(276) | 30 | ||||
| Hot-Rolled Sheet: | ||||||||
| UNS N08825 | annealed | 85(586) | 35 (241) | 30 | ||||
| UNS N08221 | annealed | 79(544) | 34(235 | 30 | ||||
| UNS N06845 | annealed | 100 (690) | 40(276 | 30 | ||||
| Cold-Rolled Sheet: | ||||||||
| UNS N08825 | annealed | 85(586 | 35 (241) | 30 | ||||
| UNS N08221 | annealed | 79(544) | 34 (235) | 30 | ||||
| UNS N06845 | annealed | 100 (690) | 40 (276) | 30 | ||||
| Cold-Rolled Strip: | ||||||||
| UNS N08825 | annealed | 85(586)B | 35 (241) | 30B | ||||
| UNS N08221 | annealed | 79(544)B | 34 (235) |
30B |
||||
| UNS N06845 | annealed | 100(690)B | 40(276) | 30 | ||||
A Yield strength requirements do not apply to material under 0.020 in. (0.51 mm) in thickness.
B Not applicable for thickness under 0.010 in. (0.25 mm).
Size Tolerances for Plates, Sheets, and Strips:
ASTM B424 specifies tolerances for dimensions such as thickness, width, and length to ensure product uniformity and quality.
| Product | Thickness,in.(mm) |
| Hot-rolled plateA | 3/16(4.76)and over |
| Cold-rolled plateA | 3/16 to 3/8(4.8 to 9.5),incl |
| Hot-rolled sheetA | 0.018 to 0.250 (0.46 to 6.4),incl |
| Cold-rolled sheetB | 0.018 to 0.250 (0.46 to 6.4)incl |
| Cold-rolled stripB | 0.005 to 0.250 (0.13 to 6.4)incl |
A Material 3⁄16 to 1⁄4 in. (4.8 to 6.4 mm), incl, in thickness may be furnished as sheet or plate provided the material meets the specification requirements for the condition ordered.
B Material under 48 in. (1219 mm) in width may be furnished as sheet or strip provided the material meets the specification requirements for the condition ordered.
Quality Inspection and Testing:
Quality inspection and testing are crucial to ensuring compliance with ASTM B424 standards. Common inspection and testing methods include:
- Chemical Composition Analysis: Performed using techniques like optical emission spectroscopy (OES) or inductively coupled plasma (ICP) analysis.
- Mechanical Testing: Involves tensile testing, hardness testing, and impact testing to assess mechanical properties.
- Dimensional Inspection: Utilizes instruments like calipers, micrometers, and gauges to verify dimensions and tolerances.
- Non-Destructive Testing (NDT): Includes methods like ultrasonic testing (UT) and radiographic testing (RT) to detect internal defects without compromising the integrity of the material.
ASTM B424 UNS N08825 Plate Applications:
ASTM B424 nickel-iron-chromium-molybdenum-copper alloys find applications in various industries, including:
- Chemical processing
- Petrochemicals
- Power generation
- Marine engineering
- Oil and gas production
- Pollution control
Reference Standards for ASTM B424:
- ASTM E140 Standard Hardness Conversion Tables for Metals
- ASTM E29 Standard Practice for Using Significant Digits in Test Data to Determine Conformance with Specifications
- ASTM E112 Standard Test Methods for Determining Average Grain Size
- B425 Specification for Ni-Fe-Cr-Mo-Cu Alloy (UNS N08825, UNS N08821, and UNS N06845) Rod and Bar
- B906 Specification for General Requirements for Flat Rolled Nickel and Nickel Alloys Plate, Sheet, and Strip
Conclusion:
ASTM B424 standardizes the requirements for nickel-iron-chromium-molybdenum-copper alloys in plate, sheet, and strip forms, ensuring their suitability for a wide range of industrial applications. Adhering to these standards guarantees the quality, reliability, and performance of these materials in demanding environments.
