The Study Of Spheroidized Annealing Process For SCM435 Alloy Steel Wires

• Main Authors: LU,NAN-HUA, 盧南樺
• Other Authors: Yang,Chih-Cheng
• Format: Others
• Language: zh-TW
• Published: 2019
• Online Access: http://ndltd.ncl.edu.tw/handle/s94kgg

碩士 === 高苑科技大學 === 機械與自動化工程研究所 === 107 === The cold forming quality SCM435 alloy steel wire is usually used to manufacture high tension bolts for mechanical and heavy industry. The wire is generally produced by drawing wire coil into wire, followed by spheroidizing treatment to achieve the necessary formability for cold forging. The Subcritical and intercritical annealing experiments on SCM435 alloy steel wires are carried out in a commercial bell furnace with a protective atmosphere of nitrogen or hydrogen. It is experimentally revealed that the wire quality with intercritical annealing in hydrogen atmosphere furnace is much better. The influence of intercritical annealing parameters is investigated for the responses of quality characteristics of wires after spheroidized annealing operation. Taguchi method along with ANOVA is used to obtain optimal spheroidized annealing conditions to improve the mechanical properties of alloy steel wires for cold forming. It is experimentally revealed that the area reduction ratio, spheroidized annealing temperature, holding temperature and cooling temperature significantly affect the quality of annealed SCM435 alloy steel wires. The optimal combination of process parameters lead to obtaining the optimal mean tensile strength of 567.8 MPa and mean ductility of 0.361 with no prior cold drawing. For cold drawn SCM435 alloy steel wires, it is experimentally revealed that the spheroidized annealing temperature, prolonged heating time and cooling temperature significantly affect the quality of annealed SCM435 alloy steel wires. The optimal combination of process parameters lead to obtaining the optimal mean tensile strength of 591.0 MPa and mean ductility of 0.327. A comparison between the results obtained using the optimal spheroidized annealing conditions and the measures determined using the original settings shows that the new spheroidizing parameter settings effectively improve the performance measures over their values at the original settings. The cold formability of SCM435 alloy steel wires is effectively improved.