高强度钛合金螺栓成形工艺及性能研究

Forming Process and Performance of High Strength Titanium Alloy Bolt

由于使用环境严酷,火车制动系统用螺栓类紧固件需要具备良好的综合性能,如强度、塑性、韧性和耐热、耐寒及耐疲劳性能等。采用钛合金螺栓代替钢制螺栓将是制动盘螺栓的发展方向。鉴于这种情况,用钛合金制作了两种螺栓,一种螺栓的螺纹是机加工成形,另一种的螺纹是滚压成形,并测定了两种螺栓的力学性能,以探索钛合金螺栓在火车制动系统中应用的可行性。结果表明,滚压成形的钛合金螺栓具有优良的力学性能:抗拉强度1 180 MPa,屈服强度1 140 MPa,断后伸长率17%,断面收缩率66%,冲击吸收能量69 J(20℃)和49 J(-50℃),硬度35 HRC,疲劳强度与钢制螺栓相当,为350 MPa。由此可见,滚压成形的钛合金螺栓应用于轨道交通行业是可行的。

Owing to being used under a grim circumstances, fasteners such as bolts used in train breaking system need to possess good combination of properties, for example, strength, plasticity, toughness, resistance to heat, cold and fatigue, etc. It will be a tendency that this high performance bolt is made of titanium alloy instead of steel. In view of this fact, two kinds of titanium alloy bolt, i.e. , thread of one was formed by machining and the other by rolling, were made. Their mechanical properties were measured to explore whether the titanium alloy bolt can be used in train braking system. The results indicated that the rolling-formed bolt exhibited satisfactory mechanical properties： tensile strength is of 1 180 MPa, yield strength of 1 140 MPa, elongation of 17%, reduction in area of 66%, impact toughness of 69 J（ at 20℃ ） and 49 J（ at - 50℃）, hardness of 35 HRC, and fatigue strength equals to that of steel bolt of 350 MPa. From this it will be seen that the application of the rolling-formed bolt of titanium alloy to railway traffic industry is feasible.