Process design of high-strength bolt of fully pearlitic high-carbon steel

Wedge tension test of a high-strength bolt of fully pearlitic high-carbon steel

“…6, the hardness of the bolt head fails to increase at the first preforming stage and slightly decreases at the final stage owing to the softening behavior of the material. According to the simulation results in the work of Lee et al (2010), the strain values at the surface area are higher than the strain value at the center. Fig.…”

“…Bolts developed in the work of Lee et al (2010) were fastened between the upper and the bottom grip and pulled with an MTS test machine (Alliance RT/100) at a speed of 0.1 mm/s until failure. Three samples were used in the test to determine the dependence of the fracture locations on the corner fillet radius and the pitch size of the thread of the manufactured bolt.…”

“…Kim et al (2009) also showed that FP steel has a better delayed fracture strength than tempered martensitic steel if both steels have a similar tensile strength. Lee et al (2010) recently developed a process sequence for manufacturing a high-strength M8 bolt of 1600 MPa; they used an FP high-carbon steel with 0.8 wt.% carbon and an ultimate tensile strength of 1410 MPa. For the development of a proper process * Corresponding author.…”

“…These programs are used in this study. To achieve the high-strength level, Lee et al (2010) introduced the first preform by means of extrusion instead of a conventional tapered upsetting procedure because of the softening of the material. Their results show that the tool life of the forming dies is longer than in the case of a high-strength material with an ultimate tensile strength of 1600 MPa.…”

“…In this study, a wedge tension test is performed to determine the location of the failure in a bolt developed by Lee et al (2010). The mechanical strength distribution is also examined in upsetting and microhardness tests of the head, neck, and body of the manufactured bolt.…”