A Study on The Effect Heat Treatment Tempretature On Mechanical Properties And Fatigue For Steel CK35


The aim of the research is to study the influence of heat treatment temperature onmechanical properties and limit fatigue of steel CK35. Tensile, impact and fatiguerotating bending tests with the mean stress estimated to zero. All the tests of heattreatment were conducted which include heating the steel to 840 ºC and then quenchingby water and after that tempering at temperature of (200, 400, 600) ºC and then cooling inair, show that the temperatures of heat treatment improve the mechanical properties andfatigue limit before and after heat treatment. The change in microstructure of steel beforeheat treatment (ferrite and pearlite) and after quenching martensite and martempering(Trostite or Sorbite) microstructures. Shown that structural barriers that may help indepriving the growth of the crack. The mechanical properties and fatigue limit wereimproved. The electronic microscope slides-scanner (SEM) of the fractured surfaceshowed the fatigue cracks growth which may be formed under the hard phases and thenreduction in growth in the plasticity region.