关键词: 焊丝钢, 在线盐浴, 斯太尔摩延时冷却, 拉拔

Abstract: Characteristics of continuous cooling and isothermal phase transformation of C-Si-Mn-Mo-Ti welding wire were studied by means of thermal dilatometer and salt bath furnace, respectively. The industrial trial production of wire rod was completed by using Stelmor delayed cooling process and on-line salt bath process on the wire rod production line of high speed rolling mill, and then the non-annealing drawing test was carried out. The results show that the formation of martensite and bainite cannot be avoided when the C-Si-Mn-Mo-Ti welding wire steel is continuously cooled in the rate range of 0.1-20 ℃/s, and the formed martensite and bainite are in block shape of the equivalent size to the ferrite grain. After salt bath treatment, the content of bainite and martensite increases, the bainite shows an incompletely grown granular morphology, the martensite size greatly reduces to only a few microns, and their distribution is uniform and dispersed. When the wire rods produced by Stelmor delayed cooling process, brittle fracture with cup-shaped fracture caused by a large number of massive martensite of block shape occurs frequently in the core of the wire rods during the non-annealing drawing test, while the wire rods produced by in-line salt bath process are not fractured during the non-annealing drawing test, which can be directly drawn to the finished wire without annealing.

Key words: welding wire steel, in-line salt bath, Stelmor delayed cooling, drawing