| 摘要 |
Provided is a method of manufacturing a high-strength bolt including forming an alloy wire rod in the shape of a bolt, which has a two-phase structure of ferrite-pearlite and includes 0.3 wt% to 0.4 wt% of carbon (C), 0.1 wt% or less of silicon (Si), 0.4 wt% to 0.6 wt% of manganese (Mn), 0.9 wt% to 1.1 wt% of chromium (Cr), 0.2 wt% to 0.5 wt% of molybdenum (Mo), 0.05 wt% to 0.15 wt% of vanadium (V), 0.02 wt% to 0.05 wt% of aluminum (Al), 0.2 wt% to 0.5 wt% of nickel (Ni), 0.015 wt% or less of phosphorous (P), 0.015 wt% or less of sulfur (S), 0.1 wt% or less of copper (Cu), 0.01 wt% to 0.05 wt% of titanium (Ti), 0.001 wt% to 0.005 wt% of boron (B), 0.005 wt% to 0.020 wt% of nitrogen (N), 0.005 wt% or less of oxygen (O), and iron (Fe) as well as other unavoidable impurities as a remainder, performing a first heat treatment on the formed bolt in a temperature range of Ae3+20°C to Ae3+120°C, cooling the heat-treated bolt at a cooling rate of 200°C/s to 400°C/s, and performing a second heat treatment on the cooled bolt in a temperature range of 400°C to 500°C, wherein the second heat-treated bolt has a tempered martensite structure and a carbide structure including at least one selected from the group consisting of V, Ti, and Fe. |
