6.5MW核电水泵内齿圈的离子渗氮工艺

Ion nitriding technology of inner gear ring of 6.5 MW nuclear power pump

为满足核电水泵齿轮箱的大功率、长寿命、高可靠、高精度等要求,在42CrMo钢中硬调质的基体上进行深层可控离子渗氮工艺试验。结果表明,采用氮、氢混合气氛三段离子渗氮,经过工艺优化,工艺总时间为70 h左右,可获得层深为1.05 mm、表面脆性1级、表面为γ′单相组织的渗氮层,渗氮层的残余压应力最大幅值达620 MPa。此工艺应用于模数为12 mm、直径为Φ1400 mm的核电站用循环水泵齿轮箱内齿圈深层渗氮,并通过台架试验验证,取代进口产品在我国核电站服役多年。

To meet high power,long service life,high reliability and high precision requirements of nuclear power pump gear box,the deep controlled ion nitriding process experiments were carried out on the 42 CrMo steel matrix with medium hardness.The results show that when three-stage ion nitriding process with nitrogen hydrogen mixing atmosphere is adopted and using the optimized total process time of about 60 h,a nitrided layer can be obtained with 0.90 mm thickness and gradeⅠsurface brittleness,and γ′single-phase,and the maximum residual compressive stress amplitude of the nitrided layer achieves 620 MPa.This process is applied to deep nitriding of the gear ring with modulus of 12 mm and diameter of Φ1400 mm for the circulating water pump gearbox for nuclear power plants and successfully passes the bench test,and is serviced in China’s nuclear power plants for many years replacing the imported one.