4J32 Low Expansion Sealing Alloy (Fe-Ni-Co) - Glass-to-Metal Seal Supplier of Strip, Wire & Bar | Shanghai Hangbo Alloy Group
Date: 2026年8月4日 Categories: News Views: 326
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 4J32?
4J32 (Fe-Ni-Co / GB/T 15018) is a controlled-expansion sealing alloy with Ni ~32%, Co ~4%, and Fe balance, designed to match the thermal expansion of soft glasses and ceramics in hermetic electronic packaging. It is widely used for transistor bases, relay headers, and vacuum tube envelopes where glass-to-metal seals must survive thermal cycling without cracking or losing vacuum integrity. Shanghai Hangbo Alloy Group supplies 4J32 as cold-rolled strip, wire, and bar.
Key Properties
| Property | Value |
|---|---|
| Alloy Family | Fe-Ni-Co Controlled Expansion |
| Density | ~8.10 g/cm3 |
| Curie Temperature | ~230C |
| CTE (20-400C) | ~5.0-6.0 x 10^-6/K |
| Tensile (Annealed) | >= 450 MPa |
| Elongation | >= 30% |
| Key Standards | GB/T 15018 |
Product Overview
4J32 belongs to the "4J" family of controlled-expansion alloys, specifically designed for glass-to-metal and ceramic-to-metal sealing. The alloy's thermal expansion coefficient in the 20-400C range (~5.0-6.0 x 10^-6/K) closely matches the expansion of borosilicate glasses and alumina ceramics, ensuring that the glass and metal expand and contract together during thermal cycling -- preventing the tensile stress in the glass that causes radial cracking and vacuum loss.
4J32 vs 4J29 (Kovar): 4J29 (29Ni-17Co-Fe) has CTE ~4.7 x 10^-6/K for hard glass seals. 4J32 has slightly higher CTE (~5.5 x 10^-6/K) for matching specific glass compositions. The choice between them depends on the exact glass formulation specified by the electronic component design.
Chemical Composition (wt.%)
| Element | Content |
|---|---|
| Ni | 31.5-33.0 |
| Co | 3.5-4.5 |
| Mn | 0.20-0.60 |
| Si | <= 0.30 |
| C | <= 0.05 |
| Fe | Balance |
Mechanical & Physical Properties
| Property | Value |
|---|---|
| Density | 8.10 g/cm3 |
| Tensile (Annealed) | >= 450 MPa |
| Elongation | >= 30% |
| Hardness | ~75-85 HRB |
| CTE (20-300C) | ~5.5 x 10^-6/K |
| CTE (20-400C) | ~5.8 x 10^-6/K |
| Magnetic | Ferromagnetic (Curie ~230C) |
Heat Treatment
Annealing: 850-900C in dry H2 or vacuum, slow cool. Stress Relief: 400-450C after forming to prevent stress-induced CTE drift.
Applications
| Industry | Component |
|---|---|
| Electronics | Transistor bases, relay headers, diode housings |
| Vacuum Tubes | Envelope seals, electrode feedthroughs |
| Sensors | Hermetic package lids, pressure sensor housings |
| Aerospace | Sealed connectors, feedthrough insulators |
FAQ
Q1: 4J32 vs 4J29 (Kovar)? 4J29: CTE ~4.7 x 10^-6/K, higher Co (17%). 4J32: CTE ~5.5 x 10^-6/K, lower Co (4%). Choose based on glass CTE match.
Q2: Can it be plated? Yes. Standard pre-plating with nickel or gold for soldering/welding compatibility.
Q3: Price? $30-50/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
Bars | Tubes | Plates | Forgings | Welded Pipes | Fittings | Wire | Strip. SGS/BV/TUV.
