New Fe-P-based and Mn-Fe-P-based filler metals for brazing of non-alloy and low-alloys steels were developed, characterized and tested in this research. They have relatively low solidus and liquidus temperatures as well as narrow melting ranges and are cheap to produce. After a short deliberation about optimal chemical compositions with the help of already existent phase diagrams and a metallurgical analysis, 22 new alloys from 12 different alloy system were cast. 19 alloys from 9 systems were chosen to continue the research with after a preliminary check. These had their microstructures analysed, solidus and liquidus temperatures as well as melting ranges determined by DSC analysis, chemical compositions measured and microhardnes measurements performed. In the scope of wettability test, these alloys were first tested on C22 carbon steel at 1080 °C in both argon as well as nitrogen + hydrogen atmospheres. Data given by these tests was used to make a final selection of 7 of the best performing filler metals. Wettability tests at 1000 °C, 1040 °C in Ar on C22 and 15CrNiS6 steels as well as at 1080 °C on 15CrNiS6 in both atmospheres followed. These samples had their microstructures analysed and microhardnesses measured. Brazing with new alloys in nitrogen + hydrogen atmosphere was performed next. Diffusion brazing of joints created by aforementioned process for 2 h and 8 h in Ar was also performed. Brazed joints were microstructurally analysed with optical and electron microscopes as well as an EDS detector. Interactions between filler metals and base materials were examined and microhardnesses in the joints measured. In the end, joints had their shear strengths measured. Created brazed joints were also preliminarily used for diffusion brazing under 20 MPa of compressive load. These were torch brazed for 10 minutes. The tests have proven, that new Fe-P-based and Mn-Fe-P-based filler metals are suitable to be used for brazing of carbon and low-alloy steels, as they form a good joint without any intermetallic phases in the base metals due to the diffusion of P, B, C and Si. Shear strengths are in upper two thirds of usual values found in the literature. Diffusion brazing has improved Fe-P-based joints and made them ductile. Joints made with Mn-Fe-P-based brazes have shown no improvement after diffusion brazing. In general, it was proven that new materials are suitable to be used as brazes.
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