本文選題：鑄鐵　切入點：同質(zhì)焊材　出處：《蘭州理工大學(xué)》2016年碩士論文　論文類型：學(xué)位論文

【摘要】：由于鑄鐵的組織特點,鑄鐵自身具有極佳的抗震性能和耐磨性能,并且其生產(chǎn)成本較低,因此在機械領(lǐng)域鑄鐵是被使用最廣泛的合金材料。但是由于在整個鑄造過程中涉及的操作環(huán)節(jié)較多。同時,目前廣泛使用的砂型鑄造和澆注過程存在很多不確定性,因此鑄鐵產(chǎn)品的夾砂、夾渣和縮松等問題突出。如果這些缺陷不能被有效修復(fù),必將導(dǎo)致這些鑄件報廢,將直接導(dǎo)致鑄造成本的上升。因此對這些鑄件缺陷的修復(fù)就顯得尤為重要。本文研究了鑄鐵微合金同質(zhì)焊條和焊絲的焊接工藝,并分別在灰鐵和球鐵兩種材質(zhì)的試塊上,開展了不同焊接工藝(電弧冷焊、熱電弧焊和氧乙炔焊)的試驗,通過對電流、焊前預(yù)熱溫度和焊后預(yù)熱溫度的不斷調(diào)整,最終確定了最理想的焊接參數(shù)和工藝流程。并在某大型的船用和燃?xì)廨啓C鑄件上得到應(yīng)用。在電弧焊中,分別試驗了電流為160A、180A、200A和220A時,電流對焊縫熱影響區(qū)的白口化傾向和焊接缺陷的影響。得出了較為理想的焊接電流為180A。此時可以避免焊接缺陷的產(chǎn)生,又可以盡可能減小焊接區(qū)域的白口化傾向。在加熱電弧焊中,分別選擇了不同的電流(160A、180A、200A和220A)和不同的焊接前預(yù)熱溫度(300℃、400℃、500℃和600℃)進行試驗。最終得出較為合適的預(yù)熱溫度為500℃,焊接電流為180A。此時可以避免焊接區(qū)域的白口問題,同時又可以使得焊縫加工后的色澤與母材接近。在氣焊中,試驗了不同的保溫溫度(300℃、400℃、500℃和600℃)和不同的保溫時間(5min、10min、15min和20min)對焊接區(qū)域加工形貌、組織和性能的影響,焊接完畢后立即對焊接區(qū)域進行加熱處理,最終得出較理想的灰鐵較為理想的加熱溫度為500℃,烘烤持續(xù)時間為15min。球鐵較為理想的加熱溫度為600℃,烘烤持續(xù)時間為15min。此時可以獲得良好的焊縫質(zhì)量。
[Abstract]:Because of the structure characteristics of cast iron, cast iron itself has excellent seismic and wear resistance, and its production cost is relatively low. Therefore, cast iron is the most widely used alloy material in the mechanical field. However, because there are many operating links involved in the whole casting process, there are many uncertainties in the sand mold casting and pouring process, which are widely used at present. Therefore, the problems of sand inclusion, slag inclusion and shrinkage of cast iron products are prominent. If these defects cannot be repaired effectively, they will lead to the scrap of these castings. Therefore, it is very important to repair the defects of these castings. In this paper, the welding process of cast iron microalloyed homogeneous electrode and wire is studied, and it is applied to the test blocks of gray iron and ductile iron, respectively. The experiments of different welding processes (arc cold welding, hot arc welding and oxyacetylene welding) were carried out. By adjusting the current, preheating temperature before welding and preheating temperature after welding, Finally, the optimal welding parameters and technological process are determined and applied to a large marine and gas turbine castings. In arc welding, the electric current is 160 An 180 A 200 A and 220 A, respectively. The effect of current on the whitening tendency and welding defects in HAZ is obtained. The ideal welding current is 180 A. at this time, the welding defects can be avoided. In heating arc welding, the whitening tendency of welding area can be reduced as much as possible. The experiments were carried out with different electric current of 160An 180A 200A and 220A) and different preheating temperatures before welding (300 鈩，

本文編號：1594676