【摘要】：本文針對鐵鉻基釬料在鋼質(zhì)油冷器釬焊中的應用開展了試驗研究。通過對多種不同型號和結構的產(chǎn)品的試制,發(fā)現(xiàn)產(chǎn)品中存在虛焊、接頭強度低、安裝板釬縫經(jīng)壓平后開裂和母材過多溶解等問題。為研究虛焊產(chǎn)生的原因,對鐵鉻基釬料和純銅釬料的潤濕和填縫性能進行對比實驗。結果表明,鐵鉻基釬料填縫性能與純銅釬料相當,但潤濕性不如后者。此外,由于翅片尺寸精度不高,膏狀釬料涂覆過程中出現(xiàn)不均勻等缺陷,可能是虛焊產(chǎn)生的原因。分別采用T形試樣和楔形試樣研究了釬角和釬縫平行段的溶解情況。隨著釬料用量和釬焊溫度的提高,釬角溶解面積和溶解深度均增加。隨著間隙的增大,平行段溶解深度增大。溶解過程可能與釬料中的P向晶界擴散造成晶界優(yōu)先溶解有關。根據(jù)上述實驗,研究了14.4型油冷器中每個凸臺適宜的焊膏用量。對比研究了鐵鉻基釬料和純銅釬料不同間隙下釬焊304-304和304-Q235接頭的微觀組織和剪切強度。0-0.02mm間隙下,釬縫中只含有少量不連續(xù)磷化物。隨著間隙增大,釬縫中心逐漸形成連續(xù)的共晶區(qū),并且比例逐漸增大,接頭強度先下降后穩(wěn)定,斷裂形式由韌性逐步變?yōu)榇嘈�。升高溫度可以減少釬縫中的磷化物含量,但只在小間隙下才能提高接頭強度。通過重新設計芯片,使凸臺分布更密集,改善了翅片與芯片間加壓的均勻性,減小了裝配間隙,雖然仍有少量虛焊,但接頭強度提高,使產(chǎn)品達到所有可靠性試驗標準。通過改進釬料預置方式和焊模平面度,提高了產(chǎn)品強度和穩(wěn)定性。安裝板和隔圈使用純銅釬料,通道內(nèi)使用鐵鉻基釬料,可以一次完成釬焊,并解決安裝板釬縫壓平后開裂問題。對鐵鉻基釬料釬焊的鋼質(zhì)油冷器進行性能試驗和熱油腐蝕試驗,產(chǎn)品滿足規(guī)定的換熱性能要求和低銅要求。目前已將鐵鉻基釬料成功應用于14.4型油冷器中,實現(xiàn)了小批量生產(chǎn)。
[Abstract]:In this paper, the application of Fe-Cr based solder in steel oil cooler brazing has been studied. Through the trial production of many kinds of products of different types and structures, it is found that there are some problems in the products, such as virtual welding, low joint strength, cracking of the brazing joint of the mounting plate after pressing and excessive dissolution of the base metal. In order to study the causes of virtual welding, the wetting and filling properties of Fe-Cr based solder and pure copper solder were compared. The results show that the filler joint properties of Fe-Cr based solder are similar to those of pure copper solder, but wettability is not as good as that of pure copper filler metal. In addition, due to the inaccuracy of fin size and the inhomogeneity of paste solder coating process, it may be the reason of virtual welding. The dissolution of the brazing angle and the parallel section of the brazing seam were studied by using T-shaped specimen and wedge-shaped specimen respectively. With the increase of filler metal content and brazing temperature, the dissolved area and depth of soldering angle increase. With the increase of the gap, the dissolution depth of the parallel segment increases. The dissolution process may be related to the preferential dissolution of the grain boundary due to the diffusion of P to the grain boundary in the solder. According to the above experiments, the suitable amount of solder paste for each platform of 14.4 oil cooler was studied. The microstructure and shear strength of 304-304 and 304-Q235 joints brazed with iron-chromium based solder and pure copper solder with different gaps were studied. Only a small amount of discontinuous phosphates were found in the brazing joints. With the increase of the gap, a continuous eutectic zone is formed in the center of the brazing seam, and the ratio increases gradually. The strength of the joint decreases first and then stabilizes, and the fracture form changes from toughness to brittleness. The content of phosphates in brazing seam can be reduced by increasing temperature, but the strength of joint can be improved only in small gap. By redesigning the chip, the distribution of the punch is denser, the uniformity of pressure between the fin and the chip is improved, and the assembly gap is reduced. Although there is still a small amount of virtual welding, the strength of the joint is increased, which makes the product meet all the reliability test standards. The strength and stability of the product were improved by improving the preposition of solder and the flatness of the welding die. Using pure copper solder for mounting plate and ring, and iron and chromium base solder for channel, the brazing can be completed at one time, and the crack problem can be solved after the brazing joint of the mounting plate is flattened. The performance test and hot oil corrosion test of the steel oil cooler brazed with iron-chromium solder are carried out. The products meet the requirements of heat transfer performance and low copper. At present, Fe-Cr-based solder has been successfully applied in 14.4 oil cooler, and small batch production has been realized.
【學位授予單位】：哈爾濱工業(yè)大學
【學位級別】：碩士
【學位授予年份】：2015
【分類號】：TG454

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本文編號：2170220