【摘要】：目前，常用的耐熱材料主要有耐熱鋼和耐熱鑄鐵。耐熱鋼的耐熱性較好，力學性能較高，但成本較高。耐熱鑄鐵具有一定的力學性能，成本相對較低，但耐熱性不如耐熱鋼。本文以鉻含量為20%的高鉻鑄鐵為研究對象，采用加入稀土、硅的方法，研究對高鉻耐熱鑄鐵的影響。通過光學顯微鏡，研究稀土、硅對高鉻白口鑄鐵組織的影響。對不同成分的高鉻鑄鐵進行高溫氧化實驗，計算其氧化速率，分析氧化膜的組成。并對不同成分的試樣進行耐磨性、熱疲勞、硬度測試。研究結果表明： 稀土含量由0增加到0.60%，高鉻鑄鐵奧氏體由樹枝晶向柱狀晶和等軸晶轉變，碳化物由連續(xù)的網(wǎng)狀趨于塊狀和條狀發(fā)展；高鉻鑄鐵氧化速率從5.566mg·cm-2·h-1降到3.276mg·cm-2·h-1；磨損量由0.1521g降為0.1485g；高鉻鑄鐵鑄態(tài)硬度從45.2HRC增加到49.9HRC；將添加稀土的高鉻耐熱鑄鐵，在1100℃下進行熱疲勞實驗，試樣進行40次反復加熱、冷卻，均未出現(xiàn)裂紋。 硅含量低于2.5%時，高鉻鑄鐵奧氏體枝晶較多，共晶碳化物的連續(xù)程度較高，以網(wǎng)狀或條狀存在。硅含量大于2.5%時，奧氏體枝晶減少，共晶碳化物顯著的細化，以細小的塊狀和粒狀形式存在，分布均勻；隨著硅含量的增加，氧化速率先下降后上升，硅含量在2.0%時，最低為2.825mg·cm-2·h-1；隨著含硅量的增加，磨損量呈降低趨勢，，最小值為0.1468g；硅含量從1.5%增加到3.5%，高鉻鑄鐵鑄態(tài)硬度從49.3HRC增加到52.5HRC；將添加硅的高鉻耐熱鑄鐵，在1100℃下進行熱疲勞實驗，試樣進行40次反復加熱、冷卻，均未出現(xiàn)裂紋。
[Abstract]:At present, the commonly used heat-resistant materials are mainly heat-resistant steel and heat-resistant cast iron. Heat-resistant steel has better heat resistance, higher mechanical properties and higher cost. Heat-resistant cast iron has some mechanical properties and low cost, but its heat resistance is inferior to heat-resistant steel. In this paper, the effect of adding rare earth and silicon on high chromium cast iron with 20% chromium content was studied. The effect of rare earth and silicon on the microstructure of high chromium white cast iron was studied by optical microscope. High chromium cast iron with different composition was oxidized at high temperature, the oxidation rate was calculated and the composition of oxide film was analyzed. The wear resistance, thermal fatigue and hardness of the samples with different compositions were tested. The results showed that the austenite of high chromium cast iron changed from dendrite to columnar crystal and equiaxed crystal, the carbides changed from continuous mesh to block and strip, the oxidation rate of high chromium cast iron decreased from 5.566mg cm-2 h-1 to 3.276mg cm-2 h-1, the content of rare earth increased from 0 to 0.60, and the austenite of high chromium cast iron changed from dendrite to columnar and equiaxed crystal. The wear rate was reduced from 0.1521g to 0.1485g.The as-cast hardness of high-chromium cast iron was increased from 45.2HRC to 49.9HRC.The thermal fatigue test of heat-resistant cast iron with rare earth addition was carried out at 1100 鈩

本文編號：2163426