Abstract
Welding is usually avoided to apply for high carbon steel, however, in some cases welding is inevitable.
In the present paper, investigation has been made on the metallurgical effect of quenched and tempered high carbon steel on the fatigue property, by carrying out a heat treatment corresponding to the heat affected zone of welding.
The following results are obtained
(1) In a ferrite-pearlite structure, simulated heat affected and as-forged specimens have a low endurance ratio as in the past data. Normalized specimen has a ratio about 0.37 which is an ordinary value in high carbon steel.
(2) In a sorbite structure, the fatigue strength is higher than that of a ferrite-pearlite structure and also shows a higher endurance ratio.
(3) These results are explained by means of fatigue crack initiation behavior in high-cycle fatigue region which depends on macro-and micro-imhomogeneity of materials. Therefore, a sorbite structure has a constant endurance ratio because the fatigue strength is determined by the average strength of matrix. On the contrary, a ferrite-pearlite structure does not show the linear relationship between fatigue and tensile strength, because the fatigue crack initiation does not depend on the matrix strength but on the locally weakest position, i. e. ferrite phase.
