A particular type of stainless steel, Grade 302 HQ, is the subject of today’s article.
The designation 302 HQ is not standardized, American ASTM standards list the grade as UNS30430, and alternative designations are “XM-7”, “304Cu”, and “304HQ”.
What makes grade 302 HQ different from other stainless steels?
The special feature of 302 HQ stainless steel is the presence of at least 3% copper in its composition.
During cold plastic processing, copper reduces the work hardening rate compared to, for example, grade 304.
As a result, it is suitable for use in the manufacture of components with complex geometric shapes and small dimensions.
What is grade 302 HQ used for?
Grade 302 HQ is widely used in fastener manufacturing and has become the standard to produce self-tapping screws and machine screws. It is also used in the production of certain types of bolts, rivets and set screws.
The ISO 3506 standard defines 302 HQ stainless steel as fastener grade “A2”. It is commonly produced in grades 70 and 80.
Stainless steel 302 HQ: Technical specifications.
Here are some of the technical characteristics of 302 HQ stainless steel
– Corrosion resistance equal to or greater than grade 304
– Resistance to potable water with chlorides up to 200 mg/L, reduced to 150 mg/L at temperatures above 60° C
– Excellent low temperature resistance
Composition (%)
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