In Situ Observation of Martensite Lath Growth Behaviors in the Coarse Grained Heat-Affected Zone of 1.25Cr-0.5Mo Heat-Resistant Steel During Simulated Welding

In the present work, the nucleation and growth of martensite laths in the coarse grained heat-affected zone of 1.25Cr-0.5Mo steel have been systematically studied by high-temperature confocal scanning laser microscope. It is found that martensite laths preferentially nucleate on, in an increasing order of difficulty, grain boundaries, inclusions, and grain interior. However, their growth rates are governed by the degree of supercooling, and vary over a wide range from 9.4 to 162.4 μm/s.