Description / Abstract: This standard covers material and performance requirements applicable to Type Thread Rolling (TR) tapping screws, heat treated to achieve properties comparable to property class 10.9 screws with induction hardened points, in sizes 5 mm and larger.

Material Description.

Material Identification. When selecting the length of screw for any application, it should be an objective to locate the induction hardened zone beyond the exit side of the mating component as depicted in Figure 1, or to maintain a minimum length of thread engagement equal to four full form non-induction hardened threads as illustrated in Figure 2. The performance values specified in this standard are not valid for design use unless all conditions of the application are identical to the combination of laboratory conditions described in the testing procedure.

Symbols. Not applicable.

Applicability. The screws covered by this specification are suitable for use in general engineering and structural attachments.

Remarks. The curing and hydrogen embrittlement baking processes following typical coating and plating processes occur between 200 °C to 350 °C and may soften an induction hardened material. It is the responsibility of the fastener manufacturer to ensure the finished screws meet the mechanical and hardness requirements of this specification.