Double Hex Screw Grade 12.9 Alloy Steel 12-Point Head SEMS Fastener

The double hex screw is a screw with a head shaped as two coaxial offset hex; it can be driven by standard hex key tools. The shape resembles triple square and spline screw drives, but they are incompatible. The radial “height” of each arris is reduced, compared to a six-point, although their number is doubled. They are potentially capable of allowing more torque than a six-point, but greater demands are placed on the metallurgy of the heads and the tools used, to avoid rounding off and slippage. Ever Hardware provides the custom-made double head screw and customizable packaging.

Heat treating is a group of industrial and metalworking processes used to alter the physical, and sometimes chemical, properties of a material. The most common application is metallurgical. Heat treatments are also used in the manufacture of many other materials, such as glass. Heat treatment involves the use of heating or chilling, normally to extreme temperatures, to achieve the desired result such as hardening or softening of a material. Heat treatment techniques include annealing, case hardening, precipitation strengthening, tempering, normalizing, and quenching. It is noteworthy that while the term heat treatment applies only to processes where the heating and cooling are done for the specific purpose of altering properties intentionally, heating and cooling often occur incidentally during other manufacturing processes such as hot forming or welding.
12.9-grade steel means that a component manufactured from this grade of steel has 12X100 N/mm^2 tensile strength and 9 is a multiplier means 90% of 1200 = 1080 N/mm^2 is the yield strength of the grade.
Similarly, we also have grade 8.8, 10.9, 6.8 also. This is the imperial method implied by engineers to differentiate between different sets of steel grades. Mainly used to differentiate the bolts and nuts. like Grade 12.9 Hexagonal Bolt.

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