【摘要】：20Cr2Ni4是一種常見的重載齒輪鋼,雖然目前在工業(yè)系統(tǒng)中廣泛應用,但是還存在生產加工性能較差和使用壽命較短等問題,不能滿足我國現代工業(yè)產業(yè)的轉型對重載齒輪鋼的質量要求。本文在20Cr2Ni4鋼的化學成分基礎上,用元素V和Nb對20Cr2Ni4鋼微合金化,制備了包括母合金(20Cr2Ni4)在內的四種試驗鋼,研究了微合金化對齒輪鋼晶粒長大規(guī)律的影響。通過對比試驗鋼的整體強化后的組織與力學性能、淬透性和滲碳處理后的性能,研究了微合金元素對齒輪鋼的強化作用。對試驗鋼顯微組織的觀察研究表明,由于V和Nb的微合金化,試驗鋼G1、G2、G3的顯微組織中出現了它們的碳化物和氮化物。在奧氏體化的加熱過程中,這些化合物并未完全溶解,它們阻礙奧氏體晶界遷移,細化了奧氏體晶粒。在加熱溫度為880℃～960℃,保溫時間為10小時的實驗條件下,試驗鋼G1、G2、G3顯微組織中的奧氏體晶粒度隨溫度的升高變化不大,而未添加微合金元素的試驗鋼G4中奧氏體晶粒明顯長大。同一溫度下,G1、G2、G3鋼的奧氏體晶粒度等級比G4鋼高3～5級。其中添加了復合微合金元素Nb和V的G2鋼晶粒度等級最高,晶粒尺寸最小。試驗鋼經900℃淬火和180℃回火2小時后的綜合力學性能最好。對比發(fā)現,經微合金化的G1、G2、G3鋼的抗拉強度明顯高于G4鋼,其中G2鋼的強度最高,抗拉強度和屈服強度分別達到1567MPa和1325MPa。四種試驗鋼低溫回火后的延伸率差別不大,均在10%左右。微合金化處理也提高了鋼的沖擊韌性和硬度�？傮w上說,V和Nb復合微合金化對提高合金綜合力學性能的效果更顯著。淬透性測試結果顯示,添加微量V的G1鋼與母合金G4鋼的淬透性相當,而添加了 Nb的G2鋼與G3鋼的淬透性相當。作為微合金化元素,Nb對提高鋼淬透性的作用比V更顯著。滲碳處理后,四種試驗鋼表層碳濃度在0.7%～0.9%之間。添加微量V或Nb的試驗鋼表層碳濃度和滲碳后表面硬度均高于母合金。此外,微合金化也提高了試驗鋼的有效滲碳層厚度。四種試驗鋼的滲碳淬火組織都是由細小針狀馬氏體和少量的殘余奧氏體組成,心部組織都為低碳板條馬氏體。微合金化細化了試驗鋼淬火和回火組織中的馬氏體。此外,表層組織中的殘余奧氏體百分數也由于微合金化元素的加入而減少,這有利于抗疲勞和耐磨損性能的改善。磨損試驗結果顯示,V和Nb的微合金化還在一定程度上提高了齒輪鋼的耐磨損性能。無論在干磨損還是油潤滑磨損條件下,經微合金化處理的試驗鋼的耐磨損性能均好于母合金。
[Abstract]:20Cr2Ni4 is a kind of common heavy-duty gear steel. Although it is widely used in industrial system at present, it still has some problems, such as poor production and processing performance and short service life, etc. It can not meet the quality requirements of heavy duty gear steel in the transformation of modern industrial industry in China. Based on the chemical composition of 20Cr2Ni4 steel, four kinds of experimental steels, including master alloy (20Cr2Ni4), were prepared by microalloying 20Cr2Ni4 steel with elements V and Nb. The effect of microalloying on grain growth of gear steel was studied. By comparing the microstructure, mechanical properties, hardenability and Carburizing properties of the whole strengthened steel, the effect of microalloying elements on the strengthening of gear steel was studied. The observation of the microstructure of the test steel shows that due to the microalloying of V and Nb, the carbides and nitrides appear in the microstructure of the test steel G1G2G3. In the process of austenitizing, these compounds are not completely dissolved, and they hinder the migration of austenite grain boundaries and refine the austenite grains. Under the experimental conditions of heating temperature 880 鈩，

本文編號：2370172