汽车排气管的耐蚀性能设计与研究

Research and Design of Corrosion Resistant for Automobile Exhaust Pipe

通过单一和复合添加Mo和Cu的方法研究了汽车排气管用钢在氯离子腐蚀介质中耐点蚀和应力腐蚀性能行为,并通过时效处理法研究了合金化元素的析出行为及其在局部腐蚀中的作用机理。结果表明,单一添加Mo或Cu可提高排气管用钢在氯离子介质中的耐腐蚀性能,复合添加Mo、Cu能在一定程度上抑制氯离子介质中的腐蚀,其效果相对单一添加Cu元素更好,但是Cu元素的添加量不宜超过0.19%。随着时效时间的延长,应力腐蚀开裂方式逐渐从穿晶断裂转变为沿晶断裂为主,并伴随穿晶断裂的混合型断裂方式,裂纹源于点腐蚀坑并沿着点腐蚀坑扩展。

Through the method of single and composite adding of Mo and Cu,the pitting corrosion and stress corrosion resistance behavior of car＇s exhaust system in the chloride ion corrosion medium were studied. By aging treatment method,the separation behavior of alloying elements and its role in the local corrosion mechanism were studied. The results show that the single adding of Mo or Cu can improve the corrosion resistance of exhaust pipe steel. The composite adding of Mo ＋ Cu can inhibit the corrosion of exhaust pipe steel in chlorine ion to a certain extent,which shows better effect than single adding Cu element,but Cu element should not be more than 0.19%. With the extension of aging time,the stress corrosion cracking way gradually shifts from transgranular fracture to the intergranular fracture priority with transgranular mixed fracture. The crack originates from some corrosion pits and extends along the pitting corrosion pit.