Iron-nickel alloy with low coefficient of thermal expansion for making shade masks

Abstract

An iron-nickel alloy has the following chemical composition (by wt %): (a) 35 at most Ni at most 37; (b) 0.001 at most C at most 0.05; (c) Mn at most 0.10; (d) Si at most 0.15; (e) Co at most 0.5; (f) S less than 0.002; (g) P less than 0.006; (h) B at most 0.0005; (i) Al+Mo+Cu+Cr at most 0.15; (j) 0.15 at most 2(V+Ti)+Nb+Zr+Ta+Hf at most 0.2; (k) 0.0025 at most N+O at most 0.015; (l) possibly some calcium and / or magnesium with a total content between 0.0001 and 0.005; (m) a balance of iron and inevitable production impurities. An Independent claim is also included for the fabrication of a strip of the above alloy by hot rolling.

Description

Technical field [0001] The present invention relates to an iron-nickel-based alloy with a very low expansion coefficient. The alloy is particularly useful for manufacturing shadow masks of color developing cathode ray tubes. Background technique [0002] In order to avoid local deformation of shadow masks used in color developing cathode ray tubes due to thermal expansion, it is desirable to use an alloy having the lowest possible thermal expansion coefficient to make them. Therefore, for example, a well-known FeNi alloy called Invar is used, which contains about 36% nickel and about 0.3% manganese. This alloy has about 1×10 -6 / k The coefficient of thermal expansion between 20°C and 100°C. [0003] However, the coefficient of expansion is still too high for some applications such as flat screens, so it is proposed to use FeNi alloys in which a small percentage of nickel is replaced by cobalt. The advantage of this alloy is that it has a 60% reduction of about 0.4×10 -6 / k therma...

AI Technical Summary

Problems solved by technology

Currently, the mechanical properties of the prior art alloys are not good enough to allow the thickness of the shadow mask to be reduced while allowing the mask to withstand possible deformations during the various shipping and handling steps

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