火焰调修工艺对转向架用钢SMA490BW性能的影响

采用火焰调修工艺对高速动车组转向架用钢SMA490BW材料进行了变形调修,并对不同加热温度后进行喷水冷却的材料组织和性能进行研究。结果表明:经火焰调修后,屈服强度、抗拉强度和延伸率都满足SMA490BW规定的要求,呈延性断裂特征,未改变材料断裂的特征属性。随着火焰加热温度的升高,材料的屈服强度、抗拉强度变化不大,断后伸长率有所降低。当火焰加热温度为750℃～850℃时,处于Ac1与Ac3的双相区,冷却后的组织为细化的铁素体、珠光体和少量粒状贝氏体以及少量的原始块状铁素体。当温度达到900℃时,加热温度超过Ac3,由于奥氏体快速冷却形成的贝氏体含量增加,导致材料冲击韧性降低。退火工艺对金相组织结构没有影响,但可以消除内应力,降低硬度,从而改善塑性和韧性。

Research on the influence of SMA490BW properties by flame adjustment for bogies

Flame adjustment technology was employed to rectify the welding distortion of SMA490BW for bogies,and the material’s morphology and properties cooled by water spraying with different heating temperature were analyzed,too.The results showed that yield strength,tensile strength and elongation all meet the standard and show ductile fracture feature,which didn’t change the material properties.The yield strength,tensile strength was almost the same as before.The elongation was decreased littile.When the heating temperature was about 750 ℃～850 ℃,the morphology was double phase at Ac1 and Ac3.The cooled morphology was refined ferrite,pearlite,a small amount granular bainite and original ferrite.When the temperature was higher than 900 ℃ and Ac3 temperature,the content of bainite was increased by the austenite fast cooling,so the impact toughness decreased.The annealing process didn’t influence the morphology,but can eliminate the inter stress and decreased hardness,then can improve the plastic and toughness properties.