不锈钢中钼含量的影响

摘要：<span style="font-family:宋体;">不锈钢中钼含量的影响</span> <p> <span style="font-family:宋体;">一般来说</span><span>,</span><span style="font-family:宋体;">简单的铬镍</span><span>(</span><span style="font-family:宋体;">及铬锰氮</span><span>)</span><span style="font-family:宋体;">奥氏体不锈钢仅用于要求不锈性和耐氧化性介质</span><span>(</span><span style="font-family:宋体;">比如硝酸等</span><span>)</span><span style="font-family:宋体;">的使用条件下</span><span>,</span><span style="font-family:宋体;">钼作为奥氏体不锈钢中的重要合金元素加入到钢中使其使用范围进一步扩大</span><span>,</span><span style="font-family:宋体;">钼的作用主要是提高钢在还原性介质</span><span>(</span><span style="font-family:宋体;">比</span><span>H2SO4,H3PO4,</span><span style="font-family:宋体;">以及一些有机酸和尿素环境</span><span>)</span><span style="font-family:宋体;">的耐蚀性</span><span>,</span><span style="font-family:宋体;">并提高钢的耐点腐蚀及缝隙腐蚀等性能</span><span>. <br /> 1</span><span style="font-family:宋体;">钼对组织的影响</span><span> <br /> </span><span style="font-family:宋体;">钼和铬都是形成和稳定铁素体并扩大铁素体相区的元素</span><span>,</span><span style="font-family:宋体;">钼形成铁素体的能力与铬相当</span><span>.</span><span style="font-family:宋体;">钼还促进奥氏体不锈钢中金属间相</span><span>,</span><span style="font-family:宋体;">比如</span><span>σ</span><span style="font-family:宋体;">相</span><span>,,κ</span><span style="font-family:宋体;">相</span><span>,</span><span style="font-family:宋体;">和</span><span>Laves</span><span style="font-family:宋体;">相等的沉淀</span><span>,</span><span style="font-family:宋体;">对钢的耐蚀性和力学性能都会产生不利影响</span><span>,</span><span style="font-family:宋体;">告别是导致塑性</span><span>,</span><span style="font-family:宋体;">韧性下降</span><span>,</span><span style="font-family:宋体;">为使奥氏体不锈钢保持单一的奥氏体组织</span><span>,</span><span style="font-family:宋体;">随着钢中钼含量的增加</span><span>,</span><span style="font-family:宋体;">奥氏体形成元素</span><span>(</span><span style="font-family:宋体;">镍</span><span>,</span><span style="font-family:宋体;">氮及锰等</span><span>)</span><span style="font-family:宋体;">的含量也要相应提高</span><span>,</span><span style="font-family:宋体;">以保持钢中铁素体与奥氏体形成元素之间的平衡</span><span>.<br /> 2</span><span style="font-family:宋体;">钼对性能的影响</span><span> <br /> </span><span style="font-family:宋体;">钼对奥氏体不锈钢的氧化作用不显著</span><span>,</span><span style="font-family:宋体;">因此当铬镍奥氏体不锈钢保持单一的奥氏体组织且无金属间析出时</span><span>,</span><span style="font-family:宋体;">钼的加入对其室温力学性能影响不大</span><span>,</span><span style="font-family:宋体;">但是</span><span>,</span><span style="font-family:宋体;">随着钼含量的增加</span><span>,</span><span style="font-family:宋体;">钢的高温强度提高</span><span>,</span><span style="font-family:宋体;">比如持久</span><span>,</span><span style="font-family:宋体;">蠕变等性能均获较大改善</span><span>,</span><span style="font-family:宋体;">因此含钼不锈钢也常在高温下应用</span><span>,</span><span style="font-family:宋体;">然而</span><span>,</span><span style="font-family:宋体;">钼的加入使钢的高温变形抗力增大</span><span>,</span><span style="font-family:宋体;">加之钢中常常存在少量</span><span>δ</span><span style="font-family:宋体;">铁素体因而含钼不锈钢的热衷加工性比不含钼钢为差</span><span>,</span><span style="font-family:宋体;">而且钼含量越高</span><span>,</span><span style="font-family:宋体;">热加工性能越坏</span><span>,</span><span style="font-family:宋体;">另外</span><span>,</span><span style="font-family:宋体;">含钼奥氏体不锈钢中容易一百万</span><span>κ(σ)</span><span style="font-family:宋体;">相沉淀</span><span>,</span><span style="font-family:宋体;">这将显著恶化钢的塑性和韧性</span><span>,</span><span style="font-family:宋体;">因此在含钼奥氏体不锈钢的生产</span><span>,</span><span style="font-family:宋体;">设备制造和应用过程中</span><span>,</span><span style="font-family:宋体;">要注意防止钢中金属间相的形成</span><span>.<br /> </span><span style="font-family:宋体;">钼在奥氏体不锈钢中的主要作用是提高钢的耐还原性介质的腐蚀性能和耐点腐蚀</span><span>,</span><span style="font-family:宋体;">耐缝隙腐蚀等的性能</span><span>.</span><span style="font-family:宋体;">分别为钼对铬镍奥氏体不锈钢在硝酸</span><span>,</span><span style="font-family:宋体;">硫酸</span><span>,</span><span style="font-family:宋体;">醋酸</span><span>,</span><span style="font-family:宋体;">磷酸和尿素等介质中耐蚀性的影响</span><span>,</span><span style="font-family:宋体;">可以看出</span><span>,</span><span style="font-family:宋体;">除在氧化性介质</span><span>HNO3</span><span style="font-family:宋体;">中处</span><span>,</span><span style="font-family:宋体;">钼的作用都是有益的</span><span>,</span><span style="font-family:宋体;">因此含钼的奥氏体不锈钢一般不用天耐硝酸的腐蚀</span><span>,</span><span style="font-family:宋体;">除非硝酸中含</span><span>F-,Cl-</span><span style="font-family:宋体;">等离子</span><span>,<br /> </span><span style="font-family:宋体;">虽然钼作用为合金元素对奥氏体不锈钢耐还原性介质</span><span>,</span><span style="font-family:宋体;">面点腐蚀及缝隙腐蚀的原因尚不完全清楚</span><span>,</span><span style="font-family:宋体;">但大量实验已指出</span><span>,</span><span style="font-family:宋体;">钼的耐蚀作用仅相当钢中含有较高量的铬时才有效</span><span>,</span><span style="font-family:宋体;">钼主要是强化钢中铬的耐蚀作用</span><span>,</span><span style="font-family:宋体;">与此同时</span><span>,</span><span style="font-family:宋体;">钼形成酸盐后的缓蚀作用也已为实验所证实</span><span>.<br /> </span><span style="font-family:宋体;">在耐高浓氯化物溶液的应力腐蚀方面</span><span>,</span><span style="font-family:宋体;">虽然钼作为合金元素对奥氏体不锈钢耐还原性介质</span><span>,</span><span style="font-family:宋体;">耐点腐蚀及缝隙腐蚀的原因尚不完全清楚</span><span>,</span><span style="font-family:宋体;">但大量实验已指出</span><span>,</span><span style="font-family:宋体;">钼的作用仅当钢中含有较高量的铬时才有效</span><span>,</span><span style="font-family:宋体;">钼主要是强化钢中铬的耐蚀作用</span><span>,</span><span style="font-family:宋体;">与此同时</span><span>,</span><span style="font-family:宋体;">钼形成钼酸盐后的缓冲作用也已为实验所证实</span><span>.<br /> </span><span style="font-family:宋体;">在耐高浓氯化物沉沦的应力腐蚀方面</span><span>,</span><span style="font-family:宋体;">虽然一此实验指同</span><span>.32_1.html</span><span style="font-family:宋体;">以下的钼对奥氏体不锈钢的耐应力腐蚀性能有害</span><span>,,</span><span style="font-family:宋体;">但是由于常见铬镍奥氏体不锈钢多在含有微量氯化物及饱和氧的水介质中使用</span><span>,</span><span style="font-family:宋体;">其应力腐蚀又以点腐蚀为起源</span><span>,</span><span style="font-family:宋体;">因此含钼的铬镍钼奥氏体不锈钢由于耐点腐蚀性能较高</span><span>,</span><span style="font-family:宋体;">所以在实际应用中常常比不含钼钢具有更好的耐氯化物应力腐蚀性能</span><span>.</span> </p> <p> <span></span> </p>