bolt , Iran

Iron screws are made from low-carbon steel with standard grades 4.6 to 8.8. The main chemical composition includes iron ~98%, carbon 0.1-0.3%, and manganese 0.6-1.0%. Their tensile strength ranges from 400 to 800 MPa. Common diameters from M3 to M48 with ISO standard pitch are available. The standard anti-corrosion coating is electrolytic galvanizing, 5-15 microns thick. This coating provides about 120 hours of salt spray resistance. The tightening torque for an M10 Grade 8.8 screw is about 40 Nm. Their maximum continuous operating temperature is 150°C. Low cost and sufficient strength drive their widespread industrial use.

"Dry" high-strength screws are produced from medium-carbon alloy steel with strength grades 10.9 or 12.9. The precise alloy includes carbon 0.3-0.4%, chromium 0.8-1.1%, and molybdenum 0.15-0.25%. They offer very high tensile strength, between 1000 and 1220 MPa. Quench and temper heat treatment achieves a hardness of 39-44 HRC. They are often supplied uncoated or with a black oxide coating. The black oxide layer is 2-5 microns thick and increases wear resistance. The tightening torque for an M12 Grade 10.9 screw is about 90 Nm. Main applications are in critical, heavy-load, dynamic joints like automotive and steel structures. Strict QC with UT and HT tests is mandatory.You can order and buy bolt from Iran by contacting us through whatsaap and email.
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