Production process of high strength black bolt:
Rack mounting → oil removal by boiling alkali solution → water cleaning → rust removal by hydrochloric acid solution → water cleaning → boiling water heating → oxidation → water cleaning → saponification → water cleaning → self drying → hot oil soaking → oil control → inspection → warehousing.
Quality inspection method of high strength black bolt
Place the high-strength black bolt under the fluorescent light source, 300 mm away from the naked eye, and observe its surface. If the color is uniform and there is no obvious spot and rust, it is good, and the color is black or blue black.
Loose test of oxide film: drop a few drops of 3% copper sulfate solution on the high-strength blackened bolt after degreasing, and it is qualified if there is no copper color within 30s.
Construction Hex Bolts A490M, Custom Design CONSTRUCTION FASTENERING Hardware Heavy Bolt for Steel Constructions A325M A490M, m30 a490 bolt high tension bolts and nuts, Grade 10.9 ASTM A490 High Strength Tc Bolts ASTM A490 High Strength Black Oxide Hex Head Bolt Features: Material:High strength/tensile Grade:A490 Standard:ASTM […]
ASTM A490 Bolts High Strength Construction Hex Bolts, A490 Hexagonal Bolt Made in China, Heavy Hex Bolt A490 Bolts and Nuts, Custom Design CONSTRUCTION FASTENERING Hardware Heavy Bolt for Steel Constructions A325M A490M ASTM A490 Bolts High Strength Construction Hex Bolts Features: Material:High strength/tensile Grade:A490 Standard:ASTM […]
