Abstract
The article deals with the investigation of fracture reasons of zigzag springs made from patented and tempered hypereutectoid steel wires. Microscopy analysis was performed for identification of quality of springs’ material. It was specified that index i of non-metallic inclusions was the lowest according standard EN 10270-1:2011, i.e. i = 0.5 and surface defects such as decarburization and roughness examining twelve occasionally collected samples did not exceed the permissible limits. A number of wire rods with cleaned surface from phosphate coating were tempered: 1) in industrial furnace together with spring pallets, 2) in laboratory furnace with welded thermocouples for precise temperature determination. Comparison of colours of oxides films revealed that during tempering of spring pallets in industrial furnace they did not reach the required temperature of 300 °C. The average of temperature inside the chamber of industrial furnace reached just 200-240 °C. The tensile test of steel wires tempered at different temperatures heating for various durations allowed selection of the optimal regime of heat treatment of hypereutectoid steel springs. DOI: http://dx.doi.org/10.5755/j01.mech.22.5.15434
Highlights
The high strength springs usually are produced from hypereutectoid steel wires containing 0.7-0.9 % carbon [1,2,3,4,5]
Hypereutectoid steel wires have very fine pearlitic microstructure that is obtained by a special heat treatment process called patenting [5, 6]
Seeking to decrease the remained stresses and to increase elasticity and relaxation resistance of material, the coiled springs are tempered at 200-300 °C temperature
Summary
The high strength springs usually are produced from hypereutectoid steel wires containing 0.7-0.9 % carbon [1,2,3,4,5]. The case of fracture of spring (i) can be divided into the following several cases: volume defects, these can be defined as non-metallic inclusions directly related with material quality [8, 9]; surface defects as high roughness, decarburization because of heat treatment, scratches, cracks, corrosion affected areas, etc. These mentioned defects are monitored according requirements of standard documents [10,11,12]. The found decarburization did not exceed the permissible limits mentioned in standard EN 10270-1 but in spite of that it showed facilitated conditions of crack
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
