铬系白口铸铁腐蚀磨损特性的研究

本文研究了共晶碳化物数量在20—25％范围内,含铬量由2—24％,铸态及热处理态的铬系白口铸铁在不同介质条件下的腐蚀磨损特性.研究结果表明:在强酸性介质中,腐蚀是导致腐蚀磨损失重量增大的主要因素,含铬量较高的奥氏体有较好的腐蚀磨损抗力,碳化物存在没有任何益处;在弱酸性介质中,腐蚀与磨损共同对腐蚀磨损失重量起作用,提高基体含铬量,保持适当数量碳化物将有效地提高其腐蚀磨损抗力;在中性及碱性介质中,磨损是主要影响因素,提高基体硬度有助于腐蚀磨损抗力的提高.合金元素铜可降低基体腐蚀速度,促进基体钝化,且有利于腐蚀磨损抗力的改善.本文研究结果为杂质泵过流部件的选材提供了依据.

A STUDY OF THE CORROSION-ABRASION CHARACTERISTICS OF CHROMIUM WHITE CAST IRONS

This paper studies the corrosion-abrasion characteristics of as-cast and heat-treated chromium white cast irons containing 2-24% in weight percentage with volume fractions of eutectic carbides varying within 20-25%. Sand erosion tests are carried out in different pH value conditions. The results show that the corrosion-abrasion charcteristics of chromium white cast iron are closely related to the corrosive media, the chemical compositions of cast irons and their microstructures. In acidic media, corrosion plays a significant role in the increase of weight loss. The austenitic matrix containing comparatively high chromium content is more resistant to corrosion and corrosion-abrasion than the martensite and the eutectic carbides do not give contribution to it. In weak acidic media, the corrosion rate of chromium white cast irons is much lower than that in acidic media and the matrices with high chromium content are easily passivated. An improvement in corrosion-abrasion resistance can be achieved by increasing the chromium content in matrix and keeping the proper amount of euteotic carbides. In neutral and basic media, abrasion plays a main role and martensite behaves better than austenite and sorbite. Copper, as an alloying elements, can decrease the corrosion rate of matrices and promote passivation of matrices, so that copper can improve the corrosion-abrasion resistance of chromium white cast irons. The results provide scientific basis in the materials selection for wear parts of slurry pumps.