10.9级贝氏体型非调质钢U形螺栓的试制

Research on the Properties of Microalloyed Bainitic Steel for Grade 10.9 U-Bolts

研究了冷拔减面率以及时效处理对一种贝氏体型冷作强化非调质钢组织和力学性能的影响,并采用该钢试制10.9级U形螺栓.研究结果表明,随着冷拔减面率的增加,材料的强度开始时显著增加,当冷拔减面率为26％时,抗拉强度达到最大值1134 MPa,这是由于当减面率达到26％时,应变硬化指数n值达到峰值.100～500℃时效处理后,该钢的强度先增加后减小,在300℃时效处理后抗拉强度和屈服强度分别达到峰值,原因是由于碳化物在不同时效温度下析出行为的变化导致材料强度的变化,300℃时效碳化物析出尺寸细小且密度大,因此强度高.由研究结果制定最优工艺,试制的螺栓其性能满足卡车10.9级U形螺栓的要求,可以实现工业生产.

The effect of cold drawing reduction ）＇ and aging temperature on the microstrueture and mechanical prop- erties of cold hardening microalloyed bainitic steel was investigated. It is found that the tensile strength of the steel increase with the increase cold drawing reduction y to the maximum value 1 134 MPa at y= 26 %, which can be as- cribed to the work hardening exponent n increases with increasing ？＇ to the maximum value at y = 26~. The strength of the steel can be significantly affected by the ageing temperature. With increasing the temperature in be- tween 100 and 300 ~C, the strength of the steel increases, while the strength of steel decreases with the variation of temperature from 300 to 500 ~C. The change of the strength can be attributed to the difference of carbide parti- cles precipitation with the variation of temperature. Also, the U-bolts produced hy using the results of the study have been tested. The result shows that the microstructure and properties of the U-bolts can meet the mechanical requirement of grade 10.9 U-bolts.