4J42 Controlled Expansion Alloy Bar FeNi42 Glass Sealing Alloy
4J42 Controlled Expansion Alloy Bar is an iron-nickel precision alloy bar containing approximately 42% nickel. It is widely known as FeNi42 Bar, Alloy 42 Bar, Nilo 42 Bar, UNS K94100 Bar, W.Nr. 1.3917 Bar and glass sealing alloy bar. The material is designed to provide a controlled and predictable coefficient of thermal expansion for glass-to-metal sealing, semiconductor lead frames, electronic packages, vacuum components and precision instruments.
SAKY STEEL supplies 4J42 round bar, FeNi42 rod, Alloy 42 forged bar, bright bar, peeled bar, polished bar, centerless ground bar and customized machined components. Diameter, length, surface finish, tolerance, delivery condition and inspection requirements can be customized according to customer drawings and technical specifications.
Product Parameters
| Item | Product Details |
|---|---|
| Product Name | 4J42 Controlled Expansion Alloy Bar / FeNi42 Glass Sealing Alloy Bar |
| Grade | 4J42 / Alloy 42 / FeNi42 / Nilo 42 / UNS K94100 / W.Nr. 1.3917 |
| Material Type | Iron-nickel controlled expansion alloy and glass sealing alloy |
| Available Shapes | Round bar, rod, forged bar, flat bar, square bar and machined component |
| Diameter Range | 3 mm to 300 mm; larger forged dimensions available upon request |
| Length | 1000 mm to 6000 mm or custom cut-to-length |
| Surface Finish | Black, bright, peeled, turned, polished, centerless ground or machined |
| Delivery Condition | Annealed, hot rolled, forged, cold drawn, stress relieved or customer specified |
| Standards | ASTM F30, GB/T 15018, DIN 17745 or customer technical specification |
| Tolerance | Standard commercial tolerance, h9, h11, ground tolerance or drawing-specific tolerance |
| Certificates | MTC, EN 10204 3.1, PMI report, dimensional report and third-party inspection |
Chemical Composition
The chemical composition of 4J42 controlled expansion alloy is carefully balanced to obtain stable thermal expansion behavior. Nickel content is especially important because it directly affects the expansion curve and compatibility with glass, ceramic and silicon components. The following values are typical references; final results should be verified against the applicable specification and Mill Test Certificate.
| Element | Typical Content (%) | Function in Alloy |
|---|---|---|
| Nickel (Ni) | Approximately 41.0–42.5 | Controls the thermal expansion rate and alloy structure |
| Iron (Fe) | Balance | Forms the base of the Fe-Ni controlled expansion alloy |
| Manganese (Mn) | ≤ 0.80 | Supports melting control and processing performance |
| Silicon (Si) | ≤ 0.30 | Controlled residual affecting sealing and processing behavior |
| Carbon (C) | ≤ 0.05 | Controlled to preserve ductility and expansion stability |
| Chromium (Cr) | ≤ 0.25 | Restricted residual element under common Alloy 42 specifications |
| Aluminum (Al) | ≤ 0.10 | Controlled to maintain sealing and expansion performance |
| Phosphorus (P) | ≤ 0.025–0.030 | Controlled impurity for mechanical reliability |
| Sulfur (S) | ≤ 0.025–0.030 | Controlled impurity for clean structure and workability |
Mechanical Properties
Mechanical properties of 4J42 Alloy Bar depend on bar diameter, annealing cycle, cold reduction, forging process and final delivery condition. The following data provides general engineering guidance and should not replace the values specified in the purchase order or actual MTC.
| Property | Typical Reference | Engineering Significance |
|---|---|---|
| Tensile Strength | Approximately 490–520 MPa | Provides adequate strength for sealing and precision components |
| 0.2% Yield Strength | Approximately 250–280 MPa | Relevant to forming, machining and component loading |
| Elongation | Approximately 30–43% | Supports cold forming and fabrication in annealed condition |
| Hardness | Approximately 70–85 HRB annealed | Useful for machining and forming process selection |
| Density | Approximately 8.12 g/cm³ | Used for product weight and logistics calculations |
| Elastic Modulus | Approximately 145–150 GPa | Supports dimensional and structural calculations |
| Thermal Expansion | Approximately 4.0–5.5 × 10⁻⁶/°C over selected ranges | Core property for glass, ceramic and silicon sealing systems |
| Magnetic Property | Magnetic | Should be considered in electronic and instrument design |
Common Size Table
| Diameter | Typical Length | Common Finish | Typical Application |
|---|---|---|---|
| 3–10 mm | 1000–3000 mm | Bright, cold drawn, polished or ground | Sealing pins, electronic terminals and precision rods |
| 12–30 mm | 2000–6000 mm | Bright, peeled, polished or centerless ground | Thermostat rods, lead-frame tooling and machined sealing parts |
| 32–80 mm | 2000–6000 mm | Black, peeled or rough turned | Electronic housings, sealing rings and CNC components |
| 85–150 mm | Cut-to-length | Forged, rough turned or machined | Large glass sealing parts and precision instrument components |
| Above 150 mm | Customized | Forged and rough machined | Project-specific forgings and large precision alloy components |
Different Specifications Comparison
| Product Form | Main Feature | Recommended Application | Selection Advice |
|---|---|---|---|
| 4J42 Round Bar | Balanced machinability and dimensional control | Machined pins, rods, supports and sealing components | Preferred for standard CNC-machined parts |
| 4J42 Forged Bar | Suitable for larger cross-sections and custom shapes | Large rings, sealing parts and precision forgings | Choose when standard rolled dimensions are insufficient |
| 4J42 Bright Bar | Improved surface quality and dimensional accuracy | Electronic parts, precision rods and visible components | Suitable when appearance and tolerance are important |
| 4J42 Ground Bar | Tighter diameter tolerance and smoother surface | Precision shafts, sealing pins and automatic machining | Recommended for close-tolerance components |
| 4J42 Flat Bar | Suitable for machined rectangular components | Electronic supports, sealing fixtures and precision assemblies | Choose when rectangular geometry is required |
| 4J42 Strip or Sheet | Suitable for stamping and forming | Semiconductor lead frames and glass sealing shells | Choose when thin and flat geometry is required |
Comparison with Other Controlled Expansion Alloys
| Grade | Nominal Alloy Type | Main Characteristic | Typical Application |
|---|---|---|---|
| 4J36 / Invar 36 | Fe-36Ni | Very low expansion around room temperature | Gauges, precision instruments and dimensional standards |
| 4J42 / Alloy 42 | Fe-42Ni | Expansion compatible with selected glass, ceramic and silicon materials | Lead frames and glass-to-metal sealing parts |
| 4J46 / Alloy 46 | Fe-46Ni | Higher expansion than Alloy 42 | Selected glass and ceramic sealing systems |
| 4J50 / Alloy 50 | Fe-50Ni | Higher controlled expansion range | Glass seals and electronic assemblies |
| 4J29 / Kovar Type | Fe-Ni-Co | Matched expansion for borosilicate glass and ceramic packages | Hermetic packages and vacuum electronic components |
Equivalent Standards and International Names
| Standard or Naming System | Designation | Remarks |
|---|---|---|
| Chinese Grade | 4J42 | Controlled expansion precision alloy |
| UNS | K94100 | Common international Alloy 42 designation |
| European Material Number | 1.3917 | Common FeNi42 material reference |
| ASTM Reference | ASTM F30 | Specification reference for iron-nickel sealing alloys |
| Chemical Designation | FeNi42 | Indicates approximately 42% nickel with iron balance |
| Common Trade Names | Alloy 42 / Nilo 42 / Glass Sealing 42 | Commercial names used by different producers and suppliers |
| Russian Reference | 42Н / 42H | Common regional designation or similar alloy reference |
| Alloy Family | Controlled Expansion Alloy | Part of the 4J series precision expansion alloy family |
Production Process Flow
| Step | Production Process | Quality Control Focus |
|---|---|---|
| 1 | Raw Material Selection | Confirm suitable nickel and iron raw material purity |
| 2 | Vacuum or Controlled Melting | Control nickel content, residual elements and alloy homogeneity |
| 3 | Ingot Casting | Control shrinkage, segregation and internal quality |
| 4 | Homogenization | Improve chemical and structural uniformity before working |
| 5 | Hot Rolling or Forging | Control bar size, reduction ratio and grain structure |
| 6 | Annealing | Restore ductility and stabilize thermal expansion behavior |
| 7 | Cold Drawing or Straightening | Improve dimensional accuracy, straightness and surface quality |
| 8 | Peeling, Turning or Grinding | Achieve the required tolerance and surface finish |
| 9 | Inspection and Testing | Verify chemistry, dimensions, surface and thermal expansion performance |
| 10 | Marking and Export Packaging | Maintain heat number traceability and transport protection |
Product Inspection
| Inspection Item | Inspection Method | Purpose |
|---|---|---|
| Chemical Composition | Spectrometer analysis or laboratory chemical analysis | Confirm nickel content and 4J42 grade compliance |
| PMI Testing | Positive Material Identification | Prevent material mix-up and strengthen anti-fake control |
| Thermal Expansion Test | Dilatometer testing over the specified temperature range | Confirm compatibility with glass, ceramic or silicon components |
| Mechanical Testing | Tensile, yield, elongation and hardness tests | Verify delivery condition and engineering performance |
| Dimensional Inspection | Caliper, micrometer, ruler and straightness measurement | Confirm diameter, length, tolerance and straightness |
| Surface Inspection | Visual inspection and surface quality evaluation | Check cracks, pits, scale, scratches and processing defects |
| Ultrasonic Testing | UT when technically applicable and requested | Evaluate internal soundness of larger bars and forgings |
| Third-Party Inspection | SGS, BV, TÜV or customer-appointed agency | Provide independent verification before shipment |
| Material Documentation | MTC and EN 10204 3.1 certificate review | Maintain heat-number traceability and project documentation |
Product Packaging
| Packaging Item | Packaging Method | Purpose |
|---|---|---|
| Surface Protection | Anti-rust oil, plastic film, VCI paper or protective wrapping | Reduce oxidation, moisture and surface scratches |
| Bundle Packing | Bars secured with protective steel or plastic straps | Prevent movement, bending and collision during handling |
| End Protection | Plastic caps, foam or wooden end blocks | Protect machined ends and precision surfaces |
| Wooden Case or Pallet | Export-standard wooden case or reinforced pallet | Suitable for international sea, air and truck transport |
| Product Marking | Grade, size, heat number, quantity and customer mark | Maintain product identification and material traceability |
| Shipping Documents | Packing list, invoice, MTC and inspection reports | Support customs clearance and project acceptance |
Applications & Machinability
Industrial Applications
| Industry | Typical Components | Why 4J42 Is Used |
|---|---|---|
| Medical Instruments | Electronic sensor housings, sealed instrument components and precision supports | Controlled expansion supports stable sealing and accurate electronic assemblies |
| Aerospace | Electronic packages, sensor components, connectors and precision instrument parts | Dimensional stability supports temperature-sensitive aerospace electronics |
| Marine Hardware | Sealed sensors, electronic feedthroughs and control components | Suitable for expansion-controlled parts, although corrosion protection must be evaluated |
| Chemical Processing | Instrument seals, sensor housings and glass-to-metal feedthroughs | Supports hermetic instrument construction when chemical exposure is separately controlled |
| Semiconductor Industry | Lead frames, integrated circuit components and silicon-compatible parts | Thermal expansion compatibility helps reduce stress during temperature cycling |
| Electric Vacuum Equipment | Glass seals, lamp components, vacuum tubes and feedthrough rods | Matched expansion helps maintain hermetic sealing integrity |
| Precision Instruments | Thermostat rods, measuring components and dimensional assemblies | Predictable thermal expansion improves dimensional reliability |
Machinability, Welding and Heat Treatment
| Processing Property | Performance | Recommendation |
|---|---|---|
| Machinability | Machinable, but not a free-cutting material like 303 stainless steel | Use rigid equipment, sharp carbide tools, controlled feed and adequate coolant |
| Cold Forming | Good formability in properly annealed condition | Use intermediate annealing for heavy cold reduction |
| Hot Working | Can be forged and hot rolled under controlled conditions | Control working temperature and cooling to maintain uniform structure |
| Welding Performance | Generally weldable with a qualified procedure | Control heat input and verify final sealing and expansion behavior |
| Brazing and Sealing | Suitable for glass-to-metal and ceramic-to-metal sealing processes | Confirm surface cleaning, oxide condition and sealing atmosphere |
| Heat Treatment | Annealing restores ductility and stabilizes the material condition | Use controlled heat treatment based on the required expansion curve |
| Hardening Response | Not a precipitation-hardening alloy | Strength is adjusted mainly through cold work and delivery condition |
| Corrosion Resistance | Moderate and lower than 304 or 316 stainless steel | Use coatings or environmental protection in marine and chemical service |
Why Choose SAKY STEEL?
| Supplier Advantage | Customer Value |
|---|---|
| Professional Precision Alloy Supply | Supply capability for 4J42, Alloy 42, controlled expansion alloys, soft magnetic alloys, elastic alloys and precision resistance alloys. |
| Customized Dimensions | Diameter, length, machining allowance, surface finish and tolerance can be customized according to drawings. |
| Heat Number Traceability | Material marking, production records and inspection documents can be linked to the original heat number. |
| Certificate Support | We can provide MTC (Mill Test Certificate / 质保书) and EN 10204 3.1 certificate according to order requirements. |
| Inspection Capability | PMI testing, chemical analysis, mechanical testing, expansion testing, UT and third-party inspection can be arranged. |
| Anti-Fake Material Control | Grade verification, heat-number checks and document review help reduce material substitution risk. |
| Export Packaging Experience | Protective wrapping, reinforced wooden cases, pallets and customer-specific shipping marks are available. |
| Technical Support | Support for equivalent-grade review, expansion requirements, sealing applications and technical document preparation. |
FAQ
What is 4J42 Controlled Expansion Alloy Bar?
4J42 Controlled Expansion Alloy Bar is an iron-nickel precision alloy bar containing approximately 42% nickel. It is used for glass-to-metal sealing, semiconductor lead frames, electronic packages, vacuum devices and precision instrument components.
Is 4J42 the same as Alloy 42 or FeNi42?
4J42 is commonly cross-referenced with Alloy 42, FeNi42, Nilo 42, UNS K94100 and W.Nr. 1.3917. Exact interchangeability should be confirmed through chemical composition, thermal expansion requirements, standard and product condition.
What is 4J42 bar used for?
4J42 Bar is used for glass sealing rods, semiconductor lead-frame parts, electronic feedthroughs, thermostat rods, vacuum tube components, precision instrument parts and machined controlled-expansion components.
What standards apply to 4J42 alloy?
Common references include ASTM F30, GB/T 15018, DIN 17745, UNS K94100 and W.Nr. 1.3917. The final order standard should be confirmed according to the required product form and application.
Can SAKY STEEL provide 4J42 Bar with MTC?
Yes. SAKY STEEL can provide MTC (Mill Test Certificate / 质保书), EN 10204 3.1 certificate, chemical analysis report, PMI report, dimensional inspection report and other quality documents according to the purchase order.
Can the thermal expansion coefficient be tested?
Yes. Dilatometer testing can be arranged when required. The customer should provide the exact test temperature range, maximum coefficient and applicable standard because thermal expansion values vary with temperature.
Is 4J42 easy to machine?
4J42 is machinable but is not a free-cutting alloy like 303 stainless steel. Stable equipment, sharp carbide tools, controlled cutting parameters and sufficient coolant are recommended for better dimensional accuracy and surface finish.
Can 4J42 be welded?
4J42 can generally be welded using a qualified procedure. Welding heat input and post-weld condition may affect dimensional stability and sealing behavior, so the completed component should be evaluated against the final service requirements.
Is 4J42 suitable for heat treatment?
Annealing can restore ductility, relieve processing stress and stabilize the material condition. 4J42 is not a precipitation-hardening alloy, so strength is mainly influenced by cold work and delivery condition.
Is 4J42 corrosion resistant?
4J42 has moderate corrosion resistance but is not comparable with 304 or 316 stainless steel. Protective coating, plating, dry storage or environmental protection may be required in marine, humid or chemical service.
What information is required for a quotation?
Please provide the required grade, standard, diameter, length, quantity, surface finish, tolerance, delivery condition, thermal expansion requirement, sealing material, inspection documents, packaging method and delivery destination.
