Toprecision — Precision Fastening & Connection Solutions

A fastener's property class is a promise about microstructure — and microstructure is set in heat treatment. The furnace decisions determine whether a 12.9 marking is honest.

Bottom line: for most Precision Screws applications the decision comes down to load, environment and assembly method — the Precision Screws guide walks through the selection.

Two hardening philosophies

Through-hardening (quench and temper) treats the whole cross-section: the standard route for medium- and high-tensile screws, giving uniform strength with tempering tuned for toughness. Case hardening hardens only the surface of low-carbon steel, leaving a tough core — typical for small self-tapping screws where surface hardness drives thread-forming life and the core must not snap.

Tempering: the toughness dial

Quenching without tempering yields glass-brittle steel. Tempering temperature trades hardness for toughness — higher temper, lower strength, much better impact tolerance. Property classes fix the windows; running at the edge of one to chase hardness readings buys brittleness.

Decarburization: the hidden defect

• Furnace atmosphere that steals surface carbon leaves a soft or weak surface layer exactly where threads bear load.
• It is invisible without metallographic sectioning — which is why sampling plans must include them.
• Standards limit decarb depth per class; a合格 report checks it, not just hardness.

Topprecision heat-treats through controlled partner lines with atmosphere monitoring, verifies hardness and decarb per lot, and publishes process capability for temper-critical characteristics.

Key specifications at a glance

Need heat-treated high-strength fasteners?

Toprecision through-hardens and case-hardens bolts up to 12.9 grade in-house, with HRC testing on every batch. Send the required property class and hardness range — we will supply the heat treatment spec and test report. Request heat treatment support.