Cold Heading Steel

ML35 The steel wire rod ML35 belongs to quenching and tempering cold heading steel , which is used to manufacture fastening pieces such as bolt, nut, screw, etc. with high strength of property elasses 8.8.(8.8 grade) The diameters of the steel wire rod are 6.5mm 14mm, which mainly meet the requirement of 1/2 cold heading. It is mainly used to manufacture hexagon bolts and consultation is needed in advance when ML35 is used for the socket hexagon bolt. It adopts the national standard of GB/T6478. Please see the following table for the chemical compositions. GradeChemical Compositions(%)CSiMnPSCrNiCuML350.32-0.39≤0.200.30-0.60≤0.035≤0.035≤0.020≤0.020≤0.020 Our company began the trial production of the cold heading steel ML35 from 2003. In January 2005, it passed the scientific and technical achievements assessment of “the Development of the Cold Heading Steel Hot Rolled Wire Rod ML35 organized by Qingdao Science and Technology Bureau. The Expert Committee evaluated that this project reached the national leading level. ML40Cr It adopts the national standard of GB/T 6478 and the chemical compositions are as follows. GradeChemical Composition(%)CSiMnPSCrML40Cr0.38-0.45≤0.300.60-0.90≤0.035≤0.0350.9 1.2 Diameter: φ10.0mm SWRCH18A,SWRCH22A SWRCH18A and SWRCH22A belong to the surface hardening steel for cold heading and cold extruding, which are mainly used to produce dry wall screw, self tapping screw, single nail, wood screw, chipboard screw, fast screw furniture nail, flat self drilling screw, pan self drilling screw, round self drilling screw, hex flange self drilling screw, etc. It adopts the standard of JIS G 3507 for the carbon steel wire rod of cold heading. The chemical compositions are as follows: GradeChemical Compositions (%)CSiMnPSAltSWRCH18A0.15-0.20≤0.100.60-0.90≤0.030≤0.035≥0.020SWRCH22A0.18-0.23≤0.100.70-1.00≤0.030≤0.035≥0.020 The grades SWRCH18A and SWRCH22A are ML18Mn and ML22Mn in GB/T 6478-2001 respectively. The wire rod is delivered on hot rolled status. There must be no cracks in the cold heading test. The height rate of after and before cold heading is 1/2. The others should be implemented accroding to GB/T 6478-2001.The main diameters are 5.5mm and 6.5mm. 10B21 Adopting the American Standard and with no equivalent grade in China, we have the ability to produce 5.5 16mm, among which, 5.5mm is the main rolling product at present. With better plasticity, cold heading performances and better hardenability, 10B21 produced by our company can omit the spheroidizing annealing treatment for the medium carbon bolt. Grade10B21Diameter5.5mm 16mmFeaturesWith the advantages as stable contents, low harmful elements, high steel purity, less decarburizing depth, less surface defect, low original hardness of the wire rod, etc. 10B21 is mainly used to produce the standard pieces of property elasses 8.8 10.9 and it is worth spreading for such performances as being directly manufactured without annealing process, low cracking rate when cold heading and good hardenability.ApplicationIt is applicable to manufacture fasteners of property elasses 8.8 10.9 and various specifications and the components of common use.Future DevelopmentsThrough reasonable alloys additions and controlled cooling process, it can keep the hot rolled wire rod in lower hardness for the convenience of being cold heading without spheroidizing annealing treatment and can reach higher strength after heat treatment. The chemical compositions are as follows: GradeChemical Compositions (%)CSiMnPSB(Min.)10B210.18-0.23≤0.100.80-1.10≤0.030≤0.035≥0.0005