Creep And Stress Relaxation Of0Cr18Ni9Stainless Steel Spring

Helical tension spring stress relaxation process is a slight deformation of thelong-term accumulation process produces very obvious, can not easily be found.During the spring creep stress is constant, the process of increasing strain, creep andstress relaxation can lead to failure of the spring. So for spring creep and stressrelaxation room service life prediction is necessary.Firstly, produced a dynamic mechanical testing machine. Creep tests which needto be able to maintain a constant load and thermal insulation; stress relaxation testsshould be able to ensure a constant load displacement, and can always monitor theload changes need to be able to simultaneously heat. Labview-based software,according to the above demand for test equipment for the design. Before creep andstress relaxation tests were first spring tensile tests conducted to determine thebeginning of creep and stress relaxation tests required to load and temperature. As thepilot of the small spring size and load, displacement sensor test and force sensors usedin high precision. While requiring no vibration test platform and confounding factorsas possible.Spring creep tests conducted on different temperatures, the test results show thatthe temperature have a greater impact on the spring creep process. When the absolutetemperature of443K creep strain limit of9.6884, steady creep rate of0.12807,;absolute temperature of343K when the creep strain limit of9.11069, steady creeprate of0.06643. As the temperature increases, the spring limit and steady creep creepstrain rate were increased. Conducted in the spring after the thermostat, variable loadand constant load, stress relaxation tests under variable temperature. First, the impactsof the spring load and temperature. Under certain conditions of temperature, withincreasing initial load, the spring load loss rate increases; early under certain loadconditions, the temperature rise will increase the rate of loss of load of the spring.Finally, based on the Arrhenius model for creep and stress relaxation spring servicelife at room temperature is predicted. Come to the spring at room temperature, creepsituation15years of service under the limit and the steady creep strain rate, stressrelaxation load loss rate.Established in the spring of finite element software Marc finite element analysismodel of thermal expansion, the analysis and experimental results obtained forcomparison, the length of the front spring creep tests under load and after heating.The ratio between the diameter and radius of the helix between the coefficient ofthermal expansion effects were studied, no linear relationship between the aspect ratioand the coefficient of thermal expansion of the spiral structure.