摘要：<span style="font-family:宋體;">不鏽鋼中鉬含量的影響</span> <p> <span style="font-family:宋體;">一般來說</span><span>,</span><span style="font-family:宋體;">簡單的鉻鎳</span><span>(</span><span style="font-family:宋體;">及鉻錳氮</span><span>)</span><span style="font-family:宋體;">奧氏體不鏽鋼僅用於要求不鏽性和耐氧化性介質</span><span>(</span><span style="font-family:宋體;">比如硝酸等</span><span>)</span><span style="font-family:宋體;">的使用條件下</span><span>,</span><span style="font-family:宋體;">鉬作為奧氏體不鏽鋼中的重要合金元素加入到鋼中使其使用範圍進一步擴大</span><span>,</span><span style="font-family:宋體;">鉬的作用主要是提高鋼在還原性介質</span><span>(</span><span style="font-family:宋體;">比</span><span>H2SO4,H3PO4,</span><span style="font-family:宋體;">以及一些有機酸和尿素環境</span><span>)</span><span style="font-family:宋體;">的耐蝕性</span><span>,</span><span style="font-family:宋體;">並提高鋼的耐點腐蝕及縫隙腐蝕等性能</span><span>. <br /> 1</span><span style="font-family:宋體;">鉬對組織的影響</span><span> <br /> </span><span style="font-family:宋體;">鉬和鉻都是形成和穩定鐵素體並擴大鐵素體相區的元素</span><span>,</span><span style="font-family:宋體;">鉬形成鐵素體的能力與鉻相當</span><span>.</span><span style="font-family:宋體;">鉬還促進奧氏體不鏽鋼中金屬間相</span><span>,</span><span style="font-family:宋體;">比如</span><span>σ</span><span style="font-family:宋體;">相</span><span>,,κ</span><span style="font-family:宋體;">相</span><span>,</span><span style="font-family:宋體;">和</span><span>Laves</span><span style="font-family:宋體;">相等的沉澱</span><span>,</span><span style="font-family:宋體;">對鋼的耐蝕性和力學性能都會產生不利影響</span><span>,</span><span style="font-family:宋體;">告彆是導致塑性</span><span>,</span><span style="font-family:宋體;">韌性下降</span><span>,</span><span style="font-family:宋體;">為使奧氏體不鏽鋼保持單一的奧氏體組織</span><span>,</span><span style="font-family:宋體;">隨著鋼中鉬含量的增加</span><span>,</span><span style="font-family:宋體;">奧氏體形成元素</span><span>(</span><span style="font-family:宋體;">鎳</span><span>,</span><span style="font-family:宋體;">氮及錳等</span><span>)</span><span style="font-family:宋體;">的含量也要相應提高</span><span>,</span><span style="font-family:宋體;">以保持鋼中鐵素體與奧氏體形成元素之間的平衡</span><span>.<br /> 2</span><span style="font-family:宋體;">鉬對性能的影響</span><span> <br /> </span><span style="font-family:宋體;">鉬對奧氏體不鏽鋼的氧化作用不顯著</span><span>,</span><span style="font-family:宋體;">因此當鉻鎳奧氏體不鏽鋼保持單一的奧氏體組織且無金屬間析出時</span><span>,</span><span style="font-family:宋體;">鉬的加入對其室溫力學性能影響不大</span><span>,</span><span style="font-family:宋體;">但是</span><span>,</span><span style="font-family:宋體;">隨著鉬含量的增加</span><span>,</span><span style="font-family:宋體;">鋼的高溫強度提高</span><span>,</span><span style="font-family:宋體;">比如持久</span><span>,</span><span style="font-family:宋體;">蠕變等性能均獲較大改善</span><span>,</span><span style="font-family:宋體;">因此含鉬不鏽鋼也常在高溫下應用</span><span>,</span><span style="font-family:宋體;">然而</span><span>,</span><span style="font-family:宋體;">鉬的加入使鋼的高溫變形抗力增大</span><span>,</span><span style="font-family:宋體;">加之鋼中常常存在少量</span><span>δ</span><span style="font-family:宋體;">鐵素體因而含鉬不鏽鋼的熱衷加工性比不含鉬鋼為差</span><span>,</span><span style="font-family:宋體;">而且鉬含量越高</span><span>,</span><span style="font-family:宋體;">熱加工性能越壞</span><span>,</span><span style="font-family:宋體;">另外</span><span>,</span><span style="font-family:宋體;">含鉬奧氏體不鏽鋼中容易一百萬</span><span>κ(σ)</span><span style="font-family:宋體;">相沉澱</span><span>,</span><span style="font-family:宋體;">這將顯著惡化鋼的塑性和韌性</span><span>,</span><span style="font-family:宋體;">因此在含鉬奧氏體不鏽鋼的生產</span><span>,</span><span style="font-family:宋體;">設備製造和應用過程中</span><span>,</span><span style="font-family:宋體;">要注意防止鋼中金屬間相的形成</span><span>.<br /> </span><span style="font-family:宋體;">鉬在奧氏體不鏽鋼中的主要作用是提高鋼的耐還原性介質的腐蝕性能和耐點腐蝕</span><span>,</span><span style="font-family:宋體;">耐縫隙腐蝕等的性能</span><span>.</span><span style="font-family:宋體;">分彆為鉬對鉻鎳奧氏體不鏽鋼在硝酸</span><span>,</span><span style="font-family:宋體;">硫酸</span><span>,</span><span style="font-family:宋體;">醋酸</span><span>,</span><span style="font-family:宋體;">磷酸和尿素等介質中耐蝕性的影響</span><span>,</span><span style="font-family:宋體;">可以看出</span><span>,</span><span style="font-family:宋體;">除在氧化性介質</span><span>HNO3</span><span style="font-family:宋體;">中處</span><span>,</span><span style="font-family:宋體;">鉬的作用都是有益的</span><span>,</span><span style="font-family:宋體;">因此含鉬的奧氏體不鏽鋼一般不用天耐硝酸的腐蝕</span><span>,</span><span style="font-family:宋體;">除非硝酸中含</span><span>F-,Cl-</span><span style="font-family:宋體;">等離子</span><span>,<br /> </span><span style="font-family:宋體;">雖然鉬作用為合金元素對奧氏體不鏽鋼耐還原性介質</span><span>,</span><span style="font-family:宋體;">麵點腐蝕及縫隙腐蝕的原因尚不完全清楚</span><span>,</span><span style="font-family:宋體;">但大量實驗已指出</span><span>,</span><span style="font-family:宋體;">鉬的耐蝕作用僅相當鋼中含有較高量的鉻時才有效</span><span>,</span><span style="font-family:宋體;">鉬主要是強化鋼中鉻的耐蝕作用</span><span>,</span><span style="font-family:宋體;">與此同時</span><span>,</span><span style="font-family:宋體;">鉬形成酸鹽後的緩蝕作用也已為實驗所證實</span><span>.<br /> </span><span style="font-family:宋體;">在耐高濃氯化物溶液的應力腐蝕方麵</span><span>,</span><span style="font-family:宋體;">雖然鉬作為合金元素對奧氏體不鏽鋼耐還原性介質</span><span>,</span><span style="font-family:宋體;">耐點腐蝕及縫隙腐蝕的原因尚不完全清楚</span><span>,</span><span style="font-family:宋體;">但大量實驗已指出</span><span>,</span><span style="font-family:宋體;">鉬的作用僅當鋼中含有較高量的鉻時才有效</span><span>,</span><span style="font-family:宋體;">鉬主要是強化鋼中鉻的耐蝕作用</span><span>,</span><span style="font-family:宋體;">與此同時</span><span>,</span><span style="font-family:宋體;">鉬形成鉬酸鹽後的緩衝作用也已為實驗所證實</span><span>.<br /> </span><span style="font-family:宋體;">在耐高濃氯化物沉淪的應力腐蝕方麵</span><span>,</span><span style="font-family:宋體;">雖然一此實驗指同</span><span>.32_1.html</span><span style="font-family:宋體;">以下的鉬對奧氏體不鏽鋼的耐應力腐蝕性能有害</span><span>,,</span><span style="font-family:宋體;">但是由於常見鉻鎳奧氏體不鏽鋼多在含有微量氯化物及飽和氧的水介質中使用</span><span>,</span><span style="font-family:宋體;">其應力腐蝕又以點腐蝕為起源</span><span>,</span><span style="font-family:宋體;">因此含鉬的鉻鎳鉬奧氏體不鏽鋼由於耐點腐蝕性能較高</span><span>,</span><span style="font-family:宋體;">所以在實際應用中常常比不含鉬鋼具有更好的耐氯化物應力腐蝕性能</span><span>.</span> </p> <p> <span></span> </p>