20CrMnTi齿轮钢的点蚀敏感性及裂纹萌生风险

利用弱腐蚀倾向的溶液环境,控制20CrMnTi钢产生有限的亚稳态蚀点分布.运用电化学噪声法,研究了20CrMnTi钢亚稳态蚀点的萌生规律,结合ANSYS有限元计算,导入真实腐蚀形貌,对比研究了不同腐蚀条件下蚀孔周边的应力分布与裂纹萌生风险.结果表明,20CrMnTi具有较高的点蚀敏感性,其亚稳态蚀点集中在杂质相边缘优先形核,随Cl-浓度的升高,点蚀孕育期明显缩短,点蚀敏感性增大.不同Cl-浓度下引起的形核速率上升会缩短蚀点间距,表面微裂纹易连接蚀点而发生扩展,增大裂纹萌生风险.

Pitting sensitivity and crack initiation risk of 20 CrMnTi gear steel

An environment with a weak corrosion tendency was used to promote the production of a limited metastable pitting distribution in 20CrMnTi steel. The law of metastable pitting initiation was investigated by using electrochemical noise. Using the ANSYS finite element method, the stress distribution and crack initiation risk of holes were analyzed and compared under different corrosion conditions. The results indicate that the pitting sensitivity of 20CrMnTi steel is high. The initiation of metastable pitting is preferentially concentrated at the edge of the impurity phase. The pitting induction period is obviously shortened and the pitting sensi-tivity increases with an increase in the Cl- concentration. The increase in the nucleation rate induced by different Cl- concentrations reduces the distance between pitting occurrences. Thus, surface microcracks readily connect and propagate pitting, thereby enhancing the risk of crack initiation.