發(fā)布時間：2018-01-03 14:40

  本文關(guān)鍵詞：堆焊硬面合金中碳氮化物質(zhì)點(diǎn)對其組織和性能的影響　出處：《華中科技大學(xué)》2015年碩士論文　論文類型：學(xué)位論文

  更多相關(guān)文章： 馬氏體不銹鋼 藥芯焊絲 碳氮化物 組織 性能

【摘要】：現(xiàn)廣泛使用的硬面藥芯焊絲主要是利用碳與鉻、鈦、鋁、釩、鈮等形成碳化物硬質(zhì)點(diǎn),來提高硬面合金的硬度和耐磨性。由于藥芯焊絲中含碳量較高、合金元素較多,導(dǎo)致堆焊層的碳當(dāng)量較高,使其產(chǎn)生裂紋的趨勢明顯升高,再加上高碳硬面藥芯焊絲堆焊層中的碳化物常呈板條狀,這些板條狀碳化物容易在晶界聚集,造成其成分的分布不均勻,使堆焊層硬面合金的塑性降低,使用過程中容易剝落,使得與其本應(yīng)該起的作用背道而馳。本課題針對傳統(tǒng)硬面合金的不足,結(jié)合堆焊工藝,以Cr13馬氏體不銹鋼為研究對象,提出用氮代替部分碳進(jìn)行氮合金化,獲得足夠多數(shù)量彌散分布的碳氮化物硬質(zhì)相質(zhì)點(diǎn)。利用這些彌散分布的碳氮化物硬質(zhì)相來提高機(jī)械零件耐磨粒磨損性能和耐高溫磨損性能。通過優(yōu)化焊接工藝規(guī)范,在Q235鋼板上堆焊5道4層。用化學(xué)成分分析儀分析堆焊層熔敷金屬成分及含量,用高溫攝影儀觀察熔敷金屬在加熱和冷卻過程中組織變化規(guī)律,對截取試樣在450℃~600℃不同溫度下回火熱處理,用洛氏硬度計測量硬度,用金相顯微鏡觀察顯微組織,用自制磨粒磨損試驗機(jī)測量磨損失重,用高溫磨損試驗機(jī)測量試樣在500℃高溫下磨損失重,用掃描電鏡觀察堆焊層微觀組織和磨損形貌,用電子探針對第二相粒子和磨屑進(jìn)行能譜點(diǎn)分析,研究結(jié)果如下:(1)所研制的硬面藥芯焊絲堆焊層組織為馬氏體+殘余奧氏體,同時在基體和晶界分布著均勻細(xì)小的碳氮化物(Nb、V、Cr)x(C、N)y,且硬面合金組織隨著氮化鉻和氮化物形成元素釩、鈮的加入而細(xì)化,當(dāng)?shù)t添加量超過一定值時,堆焊層將形成氮?dú)饪住?2)藥芯焊絲中僅添加氮化鉻,堆焊層硬度變化不大,當(dāng)添加釩、鈮后,焊態(tài)下堆焊層硬度隨著氮化鉻含量的增加而增加。對堆焊層金屬進(jìn)行回火熱處理時,當(dāng)回火溫度在450℃以下時,堆焊層硬度幾乎沒有變化;當(dāng)回火溫度為480℃時,堆焊層硬度略有下降;繼續(xù)提高回火溫度,堆焊層硬度先回升后降低。(3)在藥芯焊絲中添加2%鈮鐵、2%釩鐵和5%氮化鉻,焊態(tài)下堆焊層耐磨粒磨損性能比碳合金化硬面合金提高約30%。采用合適的熱處理方案,氮合金化硬面合金堆焊層耐磨粒磨損性能比未熱處理時提高約15%,比碳合金化硬面合金堆焊層的耐磨粒磨損性能提高約35%。(4)高溫磨損的主要失效形式為高溫氧化皮的剝落、摩擦磨損和磨粒磨損,藥芯焊絲中添加釩鐵、鈮鐵和氮化鉻可有效提高堆焊層焊態(tài)下的耐高溫磨損性能。在磨損環(huán)境溫度為500℃時,500℃以下回火熱處理對堆焊層耐高溫磨損性能影響不大,500℃以上回火熱處理,碳合金化硬面合金堆焊層耐高溫磨損性能不斷下降,而氮合金化硬面合金堆焊層耐高溫磨損性能先提高后降低。
[Abstract]:The hard cored wire which is widely used now mainly uses carbon and chromium, titanium, aluminum, vanadium, niobium and so on to form carbide hard spots, to improve the hardness and wear resistance of hard face alloy, because of the high carbon content in the flux cored wire. With more alloy elements, the carbon equivalent of the surfacing layer is higher, and the tendency of cracks is obviously increased. In addition, the carbides in the surfacing layer of high carbon hard cored wire are often in the shape of sheet. These carbides are easily accumulated at grain boundaries, resulting in the uneven distribution of the composition, which reduces the plasticity of hardfacing alloys in the surfacing layer and is easy to peel off in the process of use. This subject aims at the shortage of traditional hard alloy, combined with surfacing welding technology, taking Cr13 martensitic stainless steel as the research object. Nitrogen is used instead of carbon for nitrogen alloying. A sufficient number of carbon and nitride hard phase particles were obtained, which were used to improve the wear resistance and high temperature wear resistance of mechanical parts. By optimizing the welding process rules, the wear resistance and wear resistance of mechanical parts were improved. Van. The composition and content of cladding metal were analyzed by chemical composition analyzer. The microstructure of deposited metal during heating and cooling was observed by high temperature photography. The samples were annealed at 450 鈩，

本文編號：1374347