Alloy 27 ASTM F-256 UNS K92801, 4J28 glass sealed and controlled expansion alloy
Note:
Glass Sealing UNS K92801 is a glass-to-metal sealing and iron-chromium alloy. Nominally with 28% of Chromium, in forms of strip, bar, wire and rod. It is used primarily for sealing to glass in electronic applications. UNS K92801 should only be considered for use at service temperatures below 300°C. The alloy is prone to sigma phase formation at temperatures close to 620°C, and exhibits brittle mechanical behavior after prolonged exposures at temperatures close to 475°C.
Grade and Chemical Composition (see Table 1)
Table 1 Grade and Chemical Composition
|
Grade
|
Chemical Composition (%)
|
|
C
|
P
|
S
|
Mn
|
Si
|
Ni
|
N
|
Cr
|
Fe
|
|
≤
|
|
4J28
|
0.12
|
0.02
|
0.02
|
1.00
|
0.70
|
0.50
|
0.20
|
27.0～29.0
|
Balance
|
Notes:
1. Under condition that the average coefficient of the linear expansion meets the requirements of the standard, the content of chromium is allowed to deviate from the stated range.
2. The shape and dimensions of the alloys are in compliance with GB/T14985.
Physical Property (see Table2 & Table 3)
Table 2 Coefficient of Linear Expansion
|
Grade
|
Heat Treatment of the Samples
|
Average Coefficient of Linear Expansion
|
|
20～530°C
|
|
4J28
|
Heat to 1100±20°C, hold for 15min., cool to room tempreture in the air.
|
10.8～11.4
|
Note:
The hardness of the annealed strip should be no more than 170. Hardness inspection is not required when the thickness of the strip is less than 0.2mm.
Table 4 Coefficient of Linear Expansion
|
Grade
|
Average Coefficient of Linear Expansion ā/(10-6/K)
|
|
20～200℃
|
20～300℃
|
20～400℃
|
20～450℃
|
20～500℃
|
20～600℃
|
20～700℃
|
20～800℃
|
|
4J28
|
10.0
|
10.5
|
10.8
|
-
|
11.1
|
11.2
|
11.6
|
11.6
|
