4J45 Low Expansion Sealing Alloy (Fe-Ni-Cr) - Soft Glass Seal Supplier of Strip, Wire & Bar | Shanghai Hangbo Alloy Group
Date: 2026年8月4日 Categories: News Views: 293
By Shanghai Hangbo Alloy Group Co., Ltd. - China Supplier | ISO 9001:2015 | Est. 2012
Contact: sales@hangboalloy.com | WhatsApp (Lisa): +86 13611656360
Quick Answer: What Is 4J45?
4J45 (Fe-Ni-Cr / GB/T 15018) is a controlled-expansion sealing alloy with Ni ~45%, Cr ~5.5%, and Fe balance, designed for hermetic seals with soft glasses (soda-lime and lead glasses) used in electronic display tubes, fluorescent lamp stems, and automotive sensor housings. Shanghai Hangbo Alloy Group supplies 4J45 as cold-rolled strip, wire, and bar.
Key Properties
| Property | Value |
|---|---|
| Alloy Family | Fe-Ni-Cr Controlled Expansion |
| Density | ~8.15 g/cm3 |
| CTE (20-400C) | ~8.0-9.0 x 10^-6/K |
| Tensile (Annealed) | >= 450 MPa |
| Elongation | >= 30% |
| Key Standards | GB/T 15018 |
Product Overview
4J45 is the soft-glass matching alloy in the 4J family. While 4J29 and 4J32 match hard borosilicate glasses, 4J45's higher CTE (~8.5 x 10^-6/K) is engineered to match the expansion of soda-lime and lead-alkali glasses -- the most common and economical glass types used in mass-produced electronic components.
The 5.5% chromium addition serves dual purpose: it raises the CTE to the target range (pure Fe-45Ni would be ~7 x 10^-6/K at 400C) and provides a tightly adherent oxide layer during the sealing process that chemically bonds the glass to the metal.
Chemical Composition (wt.%)
| Element | Content |
|---|---|
| Ni | 44.0-46.0 |
| Cr | 5.0-6.0 |
| Mn | 0.20-0.60 |
| Si | <= 0.30 |
| C | <= 0.05 |
| Fe | Balance |
Mechanical & Physical Properties
| Property | Value |
|---|---|
| Density | 8.15 g/cm3 |
| Tensile (Annealed) | >= 450 MPa |
| Elongation | >= 30% |
| CTE (20-300C) | ~7.5 x 10^-6/K |
| CTE (20-400C) | ~8.5 x 10^-6/K |
| Magnetic | Ferromagnetic |
Heat Treatment
Annealing: 850-900C in wet H2 or vacuum to develop the Cr-rich oxide layer for glass bonding. Stress Relief: 400-450C.
Applications
| Industry | Component |
|---|---|
| Lighting | Fluorescent lamp stems, incandescent bulb lead wires |
| Displays | CRT electron gun supports, VFD (vacuum fluorescent display) leads |
| Automotive | Sensor housing hermetic seals, airbag initiator headers |
| Electronics | Soft-glass diode housings, reed switch glass seals |
FAQ
Q1: 4J45 vs 4J32? 4J45: CTE ~8.5 x 10^-6/K for soft glass; 4J32: ~5.5 for hard glass. Choose based on the glass specification.
Q2: Why chromium? Cr forms the oxide layer that bonds chemically to soft glass, creating a vacuum-tight seal. Fe-Ni binary alloy alone does not wet the glass adequately.
Q3: Price? $25-40/kg EXW. Contact sales@hangboalloy.com.
Q4: Forms? Strip(0.1-2.0mm), wire(0.1-5.0mm), bar(6-50mm). SGS available.
Contact & Complete Product Range
Shanghai Hangbo Alloy Group Co., Ltd. - China Supplier | Email: sales@hangboalloy.com | WhatsApp (Lisa): +86 13611656360 | www.nickel-alloy.com
Ni: NI200-N6 | Monel: 400-K500 | Inconel: 600-725 | Incoloy: 800-A286 | Hastelloy: C-276-N | Nimonic: 75-263 | Haynes: 25-556 | Precision: 1J22-4J45 | High-Strength: 18Ni250-AerMet100-PH13-8Mo | Specialty: Alloy 20-254SMO
Bars(6-500mm) | Tubes(OD 6-610mm) | Plates(0.1-100mm) | Forgings | Welded Pipes | Fittings | Wire | Strip. SGS/BV/TUV.
