Impact of Tin and Nickel on the Brazing Properties of Silver Filler Metals and on the Strength of Brazed Joints Made of Stainless Steels

Abstract

The research involved vacuum tests of brazing properties of silver filler metals, containing tin as well as tin and nickel, and used in brazing of chromium X6Cr17 and chromium-nickel X6CrNiTi18-10 stainless steels. The research also involved testing the strength and structural properties of brazed joints made of these steels. The tests were conducted on filler metals (silver brazing alloys) B-Ag68CuSn-730/755 (Ag68Cu28Sn4) and B-Ag65CuSnNi-740/767 (Ag65Cu28Sn5Ni2) and also, for comparative purposes, on the filler metal B-Ag72Cu-780 (Ag 272 according to PN-EN ISO 17672), most commonly applied in the vacuum brazing of high alloyed stainless steels.The brazing properties of the filler metals were tested by determining their wettability by means of the spreadability method. The strength of brazed joints made of the stainless steels was examined in a shear test. Research-related structural tests involved light and electron microscopy with an energy dispersive spectrometer (EDS).The comparative analysis of the properties of the filler metals revealed the positive impact of tin and nickel on the spreadability and wettability of the silver brazing alloys as well as on the quality and the shear strength of brazed joints.Keywords: brazing, silver brazing alloys with tin and nickel, brazing properties, strength of brazed joints, stainless steel Przeprowadzono badania właściwości lutowniczych w próżni spoiw srebrnych do lutowania twardego zawierających cynę oraz cynę i nikiel dla stali nierdzewnych -chromowej X6Cr17 oraz chromowo-niklowej X6CrNiTi18-10 oraz wytrzymałości i właściwości strukturalnych połączeń lutowanych tych stali. Badaniom poddane zostały spoiwa B-Ag68CuSn-730/755 (Ag68Cu28Sn4) i B-Ag65CuSn Ni-740/767 (Ag65Cu28Sn5Ni2) oraz w celu porównawczym, najczęściej stosowane dotychczas w procesach próżniowego lutowania wysokostopowych stali nierdzewnych spoiwo B-Ag72Cu-780 (Ag 272) [18].Właściwości lutownicze spoiw badano określając ich zwilżalność metodą rozpływności. Wytrzymałość połączeń lutowanych ze stali nierdzewnych badana była w próbie ścinania. W badaniach strukturalnych zastosowano mikroskopy świetlny i elektronowy -skaningowy z spektrometrem dyspersji energii (EDS). Analiza porównawcza wykazała korzystny wpływ cyny i niklu na rozpływność i zwilżalność spoiw oraz na jakość i wytrzymałość na ścinanie połączeń lutowanych.

Combined Effect of In and Ce on Microstructure and Properties of Ag10CuZnSn Low-Silver Brazing Filler Metals

“…The corresponding fracture morphology of a brazed joint is shown in Figure 7, and combined with the EDS results shown in Table 4, it can be concluded that the A region was composed of the Cu 4 In and Ag 9 In 4 IMCs and the B region was composed of the Ce 2 Sn 3 IMC. As the IMCs are brittle, they can easily crack under stress, which decreases the shear strength of the joint [27]. According to the microstructure and shear strength, it is concluded that the optimal addition amounts of the In and Ce in the Ag10CuZnSn-xIn-yCe filler metal are 1.5 wt% and 0.15 wt%, respectively.…”

Study on Microstructure and Properties of 12Ag–Cu–Zn–Sn Cadmium-Free Filler Metals with Trace In Addition

“…Silver brazing filler metals are well known as one of the most suitable filler materials for joining copper, mild steel, stainless steel, and other alloys due to its virtue of the high strength, thermal conductivity, electrical conductivity, oxidation resistance, and suitable melting point [1,2]. Among a number of silver-based brazing filler metals, Cd-containing filler metals with silver content of 20-45% are extensively used for brazing high-precision joints of austenitic stainless steel and copper.…”

Brasagem de Aços Inoxidáveis Martensíticos Utilizando Pasta à Base de Níquel em Forno a Vácuo

“…No entanto, existe uma temperatura na qual passa a haver um efeito nocivo da difusão do metal de adição no metal base, levando à menor resistência mecânica da junta brasada. Diversos autores investigaram este fenômeno e evidenciaram que, normalmente, a resistência mecânica da junta brasada passa a diminuir a partir do momento em que se formam compostos intermetálicos frágeis ou mesmo quando existe a penetração intergranular do metal de adição no metal base [3,8,14,19].…”