| Title |
A study on the Improvement of Mechanical Properties in Cr - Mo Low alloy Steel by Cyclic Heat Treatment |
| Authors |
최병영(Byung Young Choi); 김상주(Sang Joo Kim) |
| Abstract |
An investigation was carried out on the effect of cyclic heat treatment on the strength and toughness of Cr-Mo low alloy steel. Specimens were soaked at 820℃, just above the region of austenite for 1∼3½minutes and the number of cycling was 1∼4 cycles. Alternate cyclic heat treatment in the region of austenite and (austenite＋ferrite) was also applied. Experimental results showed that the yield strength, tensile strength and impact toughness were remarkably improved by refining prior sustenite grain size from ASTM #6 to #9. But the rate of improvement in the mechanical properties was reduced with increasing number of cycle. In the condition of alternate cyclic heat treatment, the impact toughness was remarkably increased as high as 12㎏·m/㎠. The improvements in the strength and toughness by cyclic heat treatment were attributed to the grain refinement, fine carbide precipitation and the increase of lath martensite in the matrix due to carbide precipitation at lath boundary. |