After forging, raw steel features a ferrite-pearlite matrix. Quenching and high-temperature tempering produce fine, uniform tempered sorbite, striking a perfect balance of core strength and toughness. Low-temperature nitriding forms a dense white nitride compound layer on thread surfaces with negligible heat distortion, locking in precise thread tolerance.
Metallographic testing is our core quality control checkpoint: we accurately measure nitrided case depth, inspect compound layer integrity, and spot hidden defects including surface porosity and denitrification. Tuning process parameters based on metallographic analysis drastically boosts bolt wear resistance and anti-seizure performance. Our fasteners deliver long-term reliable service for automotive chassis and general construction machinery.
Standard Metallographic Sample Prep for Nitrided Fasteners
1️⃣ Rough grinding: MET-SP P400
2️⃣ Fine grinding: POS plate + 9μm PD-WT Alternative: Sequential P800–P2000 abrasive papers
3️⃣ Primary polishing: SC-JP cloth + 1μm PD-WT
4️⃣ Final polishing: ZN-ZP cloth + 0.05 SO-A439 suspension
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