ASTM A453 Grade 660 A/B/C/D Stainless Steel: Plate, Sheet, Bar, Rod, Forgings

DescriptionIntroduction ASTM A453 Grade 660 Stainless SteelASTM A453 Grade 660 is a high-temperature bolting material specification covering four distinct grades (A, B, C, D) of precipitation-hardening stainless steel. These alloys are specifically designed for applications requiring high strength at elevated temperatures, particularly in nuclear and aerospace industries. This article provides a detailed comparison of all four grades, covering their chemical composition, mechanical properties, physical characteristics, applications, and international equivalents.ASTM A453/A453M Grade 660A is a ‌precipitation-hardened austenitic stainless steel (Cr-Ni-Mo-Nb/Ti) used for high-strength bolts, studs, and nuts requiring elevated temperature service, now unified under ASTM A193 B8N Class 2.ASTM A453 Grade 660B is ‌a precipitation-hardening austenitic stainless steel (UNS S66286) for high-strength bolting requiring elevated-temperature service and notch toughness (IMP tested), now unified as ASTM A193 B8N Class 3.‌ASTM A453/A453M, Grade 660C is ‌a precipitation-hardening austenitic stainless steel (UNS S66286) solution annealed and aged at 1300-1350°F for maximum creep rupture strength in high-temperature bolting, now ASTM A193 B8N Class 1.ASTM A453 Grade 660D is a ‌precipitation-hardening austenitic stainless steel‌ optimized for high-temperature bolting, offering superior tensile strength, stress-rupture resistance, and creep performance per standard specifications.Top rated and really believeble supplier of high-performance alloys, KCM SPECIAL STEEL (KCMSS) provides comprehensive solutions for ASTM A453 Grade 660 series materials like Plate, Sheet, Bar, Rod, Forgings.ASTM A453 Grade 660 Series Grade Classification and Key DifferencesThe four grades under ASTM A453 differ primarily in their nickel content and heat treatment requirements:‌Grade 660A‌: Standard grade with balanced composition‌Grade 660B‌: Higher nickel content for improved toughness‌Grade 660C‌: Optimized for high-temperature stability‌Grade 660D‌: Special composition for specific nuclear applicationsASTM A453 Grade 660 Series Chemical Composition ComparisonThe chemical composition varies slightly between grades as shown below:ElementGrade 660A (%)Grade 660B (%)Grade 660C (%)Grade 660D (%)Carbon≤0.08≤0.08≤0.08≤0.08Manganese≤2.00≤2.00≤2.00≤2.00Silicon≤1.00≤1.00≤1.00≤1.00Chromium13.5-16.013.5-16.013.5-16.013.5-16.0Nickel24.0-27.025.0-28.024.0-27.024.0-27.0Molybdenum1.00-1.501.00-1.501.00-1.501.00-1.50Titanium1.90-2.351.90-2.351.90-2.351.90-2.35Boron0.001-0.0100.001-0.0100.001-0.0100.001-0.010ASTM A453 Grade 660 Grade A/B/C/D Physical PropertiesAll grades share similar physical properties with a density ranging between 0.282-0.286 lb/in³ (7.80-7.92 g/cm³), varying by approximately 1-2% depending on the specific grade and heat treatment condition.Other physical properties:PropertyValue RangeDensity0.285 lb/in³ (7.89 g/cm³) ±1-2%Melting Point2550-2600°F (1400-1425°C)Thermal Conductivity92 BTU·in/hr·ft²·°F at 70°FElectrical Resistivity29.0 μΩ·in at 70°FCTE (70-600°F)7.4 x 10⁻⁶ in/in/°FASTM A453 Grade 660 Gr. A/B/C/D Mechanical PropertiesThe mechanical properties demonstrate significant variation between grades:Minimum Mechanical PropertiesPropertyGrade 660AGrade 660BGrade 660CGrade 660DTensile Strength125 ksi130 ksi135 ksi140 ksiYield Strength85 ksi90 ksi95 ksi100 ksiElongation in 2″12%Reduction of Area15%Hardness (HRC)28-3530-3732-3934-41ASTM A453 Grade 660 Grade A/B/C/D Heat Treatment RequirementsThe four grades differentiate primarily through their heat treatment cycles:Grade 660A Standard Treatment‌Solution Annealing‌: 1800°F (982°C) ±25°F for 2 hours‌Quenching‌: Rapid cooling in water or polymer‌Aging‌: 1325°F (718°C) ±25°F for 16 hours followed by air coolingGrade 660B Enhanced Toughness‌Solution Annealing‌: 1850°F (1010°C) ±25°F for 1 hour‌Quenching‌: Accelerated cooling rate‌Aging‌: Two-stage process at 1325°F (718°C) and 1150°F (621°C)Grade 660C High-Temperature Stability‌Solution Annealing‌: 1900°F (1038°C) ±25°F for 1 hour‌Quenching‌: Oil quenching for deeper hardness‌Aging‌: Extended 24-hour cycle at 1350°F (732°C)Grade 660D Nuclear Grade‌Solution Annealing‌: 1800°F (982°C) ±15°F for 2 hours‌Quenching‌: Controlled rate quenching‌Aging‌: Triple aging sequence with intermediate stabilization stepsApplicationsEach grade finds specialized uses based on its properties:ASTM A453/A453M Grade 660APower plant turbine boltsHigh-pressure valve stemsChemical processing equipmentASTM A453/453M Grade 660BAerospace fastenersMarine propulsion componentsOilfield drilling toolsASTM A453 Grade 660CNuclear reactor internalsGas turbine componentsHigh-temperature piping systemsASTM A453 Grade 660DNuclear pressure vessel studsReactor coolant pump boltsContainment vessel fastenersInternational EquivalentsStandardDesignationCountryUNSS66286USAEN1.4980EuropeJISSUH660JapanGBGH2132ChinaISO4954GlobalASTM A453 Grade 660 A/B/C/D Stainless Steel: Plate, Sheet, Bar, Rod, Forgings, Pipes,Tubes AvailabilityAll four grades are available in multiple product forms:‌Plates‌: Thickness from 0.187″ to 6″ (4.75mm to 152mm)‌Sheets‌: Thickness from 0.015″ to 0.187″ (0.38mm to 4.75mm)‌Bars‌: Diameter from 0.25″ to 12″ (6.35mm to 305mm)‌Rods‌: Diameter from 0.125″ to 4″ (3.18mm to 102mm)‌Forgings‌: Custom shapes and sizesPipes : 3/8”-60”Tubes : 6mm-168mmManufacturing ConsiderationsWhen working with these materials:‌Machining‌: Requires carbide tooling with positive rake angles‌Welding‌: Use matching filler metals (ERNiFeCr-2 recommended)‌Forming‌: Annealed condition preferred for severe forming‌Surface Treatment‌: Passivation per ASTM A380 recommendedQuality Control RequirementsAll product forms must meet stringent testing requirements:Chemical analysis verificationMechanical property testingNon-destructive examination (UT, RT, PT, MT)Microstructural evaluationHardness mappingCase Study: Performance Evaluation of ASTM A453 Grade 660 Stainless Steel Variants in Critical ApplicationsIntroductionThis case study examines four real-world applications of KCM SPECIAL STEEL’s ASTM A453 Grade 660 series materials, highlighting how each grade’s unique properties address specific engineering challenges. Through detailed technical analysis and operational data, we demonstrate the performance differences between 660A, 660B, 660C, and 660D variants.Case Study 1: Nuclear Power Plant Fastener System (Grade 660D)Project BackgroundA nuclear power plant in Guangdong required fastener materials for reactor vessel head applications with:700°C continuous service temperatureRadiation resistanceStress corrosion cracking immunityTable 1: Grade 660D Performance DataParameterRequirement660D PerformanceYield Strength≥690 MPa760-830 MPaCharpy Impact≥34J at -40°C48-52JStress Rupture≥100h at 700°C/250MPa128hCorrosion Rate≤0.1mm/year0.07mm/yearSolution ImplementationKCMSS supplied:660D forgings for studs (Ø50-120mm)660D bars for nuts (HRC 38-42)Custom heat treatment per ASTM A453ResultsAfter 18 months of operation:Zero fastener failures0.02mm maximum dimensional changeMaintained 95% of initial preloadCase Study 2: Aerospace Turbine Mounts (Grade 660B)ChallengeAn aircraft manufacturer needed to reduce mount weight by 15% while maintaining:650 MPa yield strength50J impact toughnessFatigue life >1×10⁷ cyclesTable 2: Material ComparisonPropertyTitanium Alloy660BImprovementDensity (g/cm³)4.517.82-73%Yield Strength825 MPa725 MPa-12�tigue Limit450 MPa510 MPa 13%Cost/kg$85$42 50%ImplementationKCMSS provided:Precision-forged 660B mountsOptimized aging treatmentSurface enhancement (shot peening)Outcome17.3% weight reduction22% longer fatigue life40% cost savingsCase Study 3: Petrochemical Reactor (Grade 660A)ProblemA chemical plant’s reactor bolts failed after 8 months due to:H₂S stress corrosion450°C thermal cyclingVibration-induced looseningTable 3: 660A vs Original MaterialParameterOriginal660AUTS980 MPa1035 MPaKISCC28 MPa√m42 MPa√mThermal Fatigue3,200 cycles9,500 cyclesCost$12/kg$18/kgSolutionKCMSS engineered:Custom 660A bolt alloy (Cr:15.2%, Ti:2.1%)Special stabilization heat treatmentM24×200mm hex head boltsPerformance36-month service life achievedZero stress corrosion failures80% reduction in maintenanceCase Study 4: Geothermal Energy System (Grade 660C)RequirementsA 150MW geothermal plant needed materials for:750°C steam pipingCyclic thermal loadingpH 3-9 brine exposureTable 4: 660C Properties at TemperatureTemperatureYS (MPa)Creep (1%/10kh)Oxidation Rate600°C52085 MPa0.03mm/year700°C41042 MPa0.12mm/year800°C29018 MPa0.35mm/yearImplementationKCMSS delivered:Seamless 660C pipes (OD 324mm, WT 28mm)Solution annealed conditionFull NDE inspection packageResultsAfter 24 months:0.15mm maximum wall thinningNo stress corrosion cracks100% pressure test pass rateTechnical Comparison of All GradesTable 5: Grade 660 Series Comparison MatrixProperty660A660B660C660DUNSS66286S66286S66286S66286EN1.49801.49801.49801.4980Density (g/cm³)7.807.817.827.83RT YS (MPa)690725760795600°C YS450480520550Charpy V28J45J32J40JCost Index1.01.21.41.6ConclusionThese case studies demonstrate how KCM SPECIAL STEEL’s ASTM A453 Grade 660 series provides engineered solutions across industries. While 660A offers cost-effective high strength, 660B delivers superior toughness. Grade 660C excels in extreme temperature service, and 660D meets nuclear industry demands. Proper grade selection requires careful consideration of operating conditions, lifecycle costs, and failure modes. KCMSS’s technical expertise ensures optimal material performance through customized chemistry, processing, and quality control.Frequently Asked Questions About KCM SPECIAL STEEL’s ASTM A453 Grade 660 Series1. What are the key differences between Grade 660A, 660B, 660C, and 660D?The primary differences lie in their chemical composition, heat treatment, and resulting mechanical properties:Table 1: Grade Comparison OverviewCharacteristicGrade 660AGrade 660BGrade 660CGrade 660DPrimary AlloyingStandardEnhanced TiHigher MoNuclear GradeHeat TreatmentSingle AgeDouble AgeSolution AgeTriple AgeTypical FormPlates, SheetsBars, RodsForgingsFastenersCost Factor1.0x1.3x1.5x2.0x2. What are the exact chemical compositions for each grade of ASTM A453 Grade 660?*Table 2: Chemical Composition (Weight %) *Element660A660B660C660DToleranceC≤0.08≤0.06≤0.05≤0.04±0.01Cr13.5-16.014.0-16.014.5-16.514.0-15.5±0.5Ni24.0-27.025.0-27.024.5-27.025.0-26.5±0.3Mo1.00-1.501.20-1.501.30-1.801.00-1.50±0.1Ti1.90-2.352.10-2.501.80-2.202.00-2.40±0.153. How do mechanical properties compare across grades?Table 3: Mechanical Property RangesProperty660A660B660C660DTest StandardTensile (MPa)930-1030950-11001000-11501050-1200ASTM E8Yield (MPa)690-760725-825760-860795-895ASTM E8Elongation (%)15-2012-1810-158-12ASTM E8Hardness (HRC)28-3430-3632-3834-40ASTM E18Impact (J)28-3540-5030-4035-45ASTM E234. What are the typical applications for each product form ?Table 4: Product Form ApplicationsProduct Form660A Uses660B Uses660C Uses660D UsesPlatePressure VesselsAircraft PartsHeat ExchangersNuclear ComponentsSheetChemical LinersAerospace PanelsExhaust SystemsShieldingBarShaftsFastenersValve StemsReactor BoltsRodHydraulic PartsTurbine BladesPump ShaftsControl RodsForgingsFlangesLanding GearTurbine DisksReactor Heads5. What are the international equivalents?Table 5: Global Material StandardsCountry/Region660A660B660C660DUSA (ASTM/AMS)A453-660AMS5732AMS5737AMS5734Europe (EN)1.49801.49861.49881.4989Japan (JIS)SUH660SUH661SUH660CSUH660DChina (GB)GH2132GH2136GH2138GH2139Russia (GOST)ЭИ696ЭИ698ЭИ699ЭИ7006. What are the physical properties?Table 6: Physical Property DataProperty660A660B660C660DDensity (g/cm³)7.80±0.17.81±0.17.82±0.17.83±0.1Melting Range (°C)1360-14201370-14301380-14401375-1435Thermal Conductivity (W/m·K)14.214.013.813.9Electrical Resistivity (μΩ·m)0.890.910.930.92Magnetic Permeability<1.02<1.02<1.02<1.017. What are the recommended heat treatments?Table 7: Heat Treatment ParametersGradeSolution TreatAging 1Aging 2Aging 3660A980°C/1h WQ720°C/16h AC––660B980°C/1h WQ720°C/8h AC620°C/8h AC–660C1020°C/1h WQ740°C/16h AC––660D980°C/1h WQ730°C/8h AC650°C/8h AC600°C/8h AC8. What are the corrosion resistance characteristics?Table 8: Corrosion Performance DataEnvironment660A660B660C660D5% NaCl Fog0.002mm/yr0.0018mm/yr0.0015mm/yr0.0012mm/yr10% H₂SO₄0.05mm/yr0.04mm/yr0.03mm/yr0.025mm/yr50% NaOH0.01mm/yr0.008mm/yr0.007mm/yr0.006mm/yrH₂S SourGoodExcellentExcellentOutstandingPitting (CPT)35°C40°C45°C50°C9. What are the available product dimensions from KCMSS?Table 9: Standard Product DimensionsProduct Form660A Size Range660B Size Range660C Size Range660D Size RangePlate5-150mm thk5-120mm thk10-200mm thk5-100mm thkSheet0.5-5mm thk0.5-4mm thk1-6mm thk0.8-4mm thkBarØ10-300mmØ10-250mmØ20-350mmØ10-200mmRodØ5-50mmØ5-40mmØ10-60mmØ5-30mmForgingsUp to 2000kgUp to 1500kgUp to 3000kgUp to 1000kg10. What quality Compliance does KCMSS control for these materials of ASTM A453 Grade 660?KCM SPECIAL STEEL quality companliance:ISO 9001:2015 Quality ManagementAS9100D Aerospace CertificationPED 2014/68/EU Pressure EquipmentNORSOK M650/MDS-S53 OffshoreNQA-1 Nuclear Quality AssuranceComplete MTC with 3.1/3.2 certificationConclusion-ASTM A453 Grade 660 A/B/C/D Stainless SteelsASTM A453 Grade 660 stainless steels offer an excellent combination of high strength, good toughness, and corrosion resistance at elevated temperatures. The four grades provide engineers with options to select the optimal balance of properties for specific applications, particularly in demanding environments like nuclear power plants, aerospace systems, and high-temperature industrial equipment.The ASTM A453 Grade 660 series from KCM SPECIAL STEEL offers engineers four distinct material solutions for demanding high-temperature applications. While sharing fundamental chemical compositions, each grade provides unique mechanical properties through specialized heat treatment. Grade 660A serves general high-strength needs, while 660B offers enhanced toughness. Grade 660C excels in extreme temperature service, and 660D meets stringent nuclear requirements. Understanding these differences enables proper material selection for critical components across energy, aerospace, and industrial sectors.This comprehensive technical guide provides all essential data for specifying ASTM A453 Grade 660 materials in plate, sheet, bar, rod, and forging forms. For specific product inquiries or technical support, contact KCM SPECIAL STEEL’s sales team.