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JIS SNCM439 Chrome Moly Alloy Steel Bars
86.0 INR/Kilograms
Product Details:
- Application Engineering, Automotive, Machinery, Components manufacturing
- Processing Heat Treated, Annealed, or Quenched & Tempered
- Material Chrome Moly Alloy Steel
- Finish Black, Peeled, Polished, or as required
- Type Bars (Round Bars)
- Diameter 16 mm - 350 mm
- Technique Hot Rolled
- Click to view more
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JIS SNCM439 Chrome Moly Alloy Steel Bars Price And Quantity
- 1 Kilograms
- 86.0 INR/Kilograms
JIS SNCM439 Chrome Moly Alloy Steel Bars Product Specifications
- Heat Treated, Annealed, or Quenched & Tempered
- Engineering, Automotive, Machinery, Components manufacturing
- Bars (Round Bars)
- Chrome Moly Alloy Steel
- Black, Peeled, Polished, or as required
- 16 mm - 350 mm
- Hot Rolled
- Custom lengths available, Common lengths 3 to 6 meters
- SNCM439
- H9, H11, or as specified by customer
- Gears, Shafts, Bearings, Automotive parts
- JIS SNCM439
- As rolled / Annealed / Quenched & Tempered
- 13%
- Chrome (Cr), Molybdenum (Mo), Nickel (Ni)
- 47 J (Charpy V-notch)
- Up to 50 HRC (after heat treatment)
- 835 MPa
- Case hardening, Through hardening
- Bundled with steel strips, Wooden box (optional)
- Ultrasonic Testing (UT), Visual Inspection, Dimensional Inspection
- 980 - 1180 MPa
Product Description
JIS SNCM439 is a premium Japanese Industrial Standard (JIS G4053) Nickel-Chromium-Molybdenum low-alloy steel. Within the machining and engineering sectors, SNCM439 bar stock is regarded as the ultimate heavy-duty upgrade to standard chromium-molybdenum grades like SCM440 (AISI 4140).
By incorporating a substantial amount of nickel alongside chrome and moly, this grade is specifically engineered to eliminate "slack quenching" (soft cores) in massive bar cross-sections, providing uniform high-tensile strength and exceptional toughness throughout the entire bar.
1. The Chemical Blueprint
The elite mechanical behavior of SNCM439 stems from a precise balance of three primary alloying elements ($Ni-Cr-Mo$):
| Element | Composition (%) | Primary Engineering Purpose |
| Carbon (C) | $0.36% - 0.43%$ | Establishes the high baseline tensile strength and responsiveness to hardening. |
| Nickel (Ni) | $1.60% - 2.00%$ | The Core Definer: Increases deep-core hardenability and prevents brittle failure under sudden shock loads. |
| Chromium (Cr) | $0.60% - 1.00%$ | Increases overall depth-of-hardening, clean wear resistance, and surface hardness. |
| Molybdenum (Mo) | $0.15% - 0.30%$ | Combats temper brittleness, ensures uniform grain structures, and maintains strength at elevated temperatures. |
| Manganese (Mn) | $0.60% - 0.90%$ | Functions as a vital deoxidizer and stabilizes deep through-hardening during heat treatment. |
| Silicon (Si) | $0.15% - 0.35%$ | Promotes elasticity and increases yield strength across the profile. |
2. Key Physical Advantages of SNCM439 Bars
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Deep Through-Hardening: If you quench a massive 150mm diameter bar of standard chrome-moly, the rapid cooling cannot penetrate completely to the center, leaving a softer, lower-strength core. The nickel content in SNCM439 delays the internal phase transformation, allowing large-diameter bars to achieve complete, uniform structural integrity from the surface right to the center.
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Outstanding Fatigue & Torsional Endurance: This material handles alternating cyclic stresses remarkably well, making it highly reliable for high-speed spinning shafts and powertrain configurations.
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Extreme Low-Temperature Shock Resistance: Unlike simpler steels that become brittle when exposed to extreme cold, SNCM439 retains high impact energy values well below freezing.
3. Mechanical Properties (Typical Heat Treated State)
When supplied or treated to the standard Quenched & Tempered (Q+T) condition, SNCM439 bars meet or exceed these standard parameters:
-
Tensile Strength ($R_m$):$ge$ 980 MPa (often exceeding 10001100 MPa depending on tempering profile)
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Yield Strength ($R_e$, 0.2% offset):$ge$ 835 MPa
-
Elongation:$ge$ 16%
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Reduction of Area:$ge$ 45%
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Supplied Q+T Hardness: Typically 293 to 352 HB (approximately 30 to 38 HRC)
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Annealed Hardness (Soft State):$le$ 250 HB (Ideal state for precision CNC turning, deep drilling, and gear cutting to maximize tool life)
4. Typical Applications
Because of its premium structural capabilities, SNCM439 round and hexagonal bars are heavily utilized for:
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High-Torque Power Transmission: Heavy-duty transmission gears, pinion shafts, spline shafts, machine tool spindles, and worm gears.
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Automotive & Aerospace: Heavy-duty drive axles, steering knuckles, high-stress crankshafts, connecting rods, and landing gear pinions.
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Heavy Fastening: Specialized ultra-high-tensile bolts, anchor studs, and industrial clamping hardware subjected to intense continuous tension.
5. Direct Global Cross-References
If you are modifying international engineering prints or looking for local sourcing equivalents, SNCM439 maps tightly to these global standards:
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USA: AISI 4340 / SAE 4340
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Germany / Europe: DIN 1.6565 (40NiCrMo6) or DIN 1.6582 (34CrNiMo6)
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China: GB 40CrNiMoA
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United Kingdom: BS 817M40 / EN24
Machining & Welding Note: Due to its exceptional hardenability, machining SNCM439 in its fully hardened state requires rigid setups and carbide tooling. Welding is generally discouraged because the high carbon equivalent makes it highly susceptible to cold cracking. If structural welding is required, strict pre-heating to 250C300C and a post-weld stress-relief cycle are mandatory.
Versatile Mechanical Strength and Durability
SNCM439 chrome moly alloy steel bars deliver a unique blend of strength, ductility, and toughness, making them ideal for manufacturing demanding components such as gears, shafts, and bearings. Their enhanced surface hardness and superior mechanical properties ensure long-term performance and reliability in heavy-duty environments.
Customizable Supply and Processing Options
Available in a variety of finishes-black, peeled, or polished-and supplied in as-rolled, annealed, or quenched and tempered conditions, these bars cater to diverse project requirements. Custom diameters and lengths, along with precise tolerances (H9, H11, or as specified), ensure optimal fit and function for your application needs.
FAQ's of JIS SNCM439 Chrome Moly Alloy Steel Bars:
Q: How do SNCM439 chrome moly alloy steel bars achieve high surface hardness?
A: The SNCM439 bars attain high surface hardness of up to 50 HRC primarily through heat treatment methods such as case hardening or through hardening, enhancing their wear resistance and durability for heavy-duty applications.Q: What testing and inspection processes are employed to ensure quality?
A: Each bar undergoes ultrasonic testing (UT) to detect internal flaws, along with visual and dimensional inspections, ensuring compliance with stringent industry standards and customer specifications.Q: When is it recommended to use SNCM439 bars over other steel grades?
A: SNCM439 bars are preferred when applications demand high strength, excellent wear resistance, and impact toughness, such as in gears, shafts, and automotive parts requiring reliable mechanical performance under stress.Q: Where can these bars be applied effectively in industry?
A: They are extensively used in engineering, automotive, and machinery manufacturing for components like shafts, gears, bearings, and other parts exposed to dynamic loads and demanding service conditions.Q: What are the main benefits of choosing SNCM439 bars for component manufacturing?
A: Key advantages include superior hardenability, robust tensile and yield strength, good elongation, and reliable performance after heat treatment, ensuring longer service life and reduced maintenance for fabricated components.Q: How are SNCM439 bars supplied and packaged for delivery?
A: Bars are typically bundled with steel strips for standard shipments or packed in wooden boxes for additional protection, accommodating various handling and logistical requirements.Tell us about your requirement
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