The effect of solid solution treatment at 1000-1200 °C for 1-3 h

quenching or air cooling on δ- ferrite transformation in 200 mm x 1 250 mm casting slab of ultra-low carbon austenite stainless steel 00Cr24Ni13 (/% ： ≤ 0.02C

23-25Cr

13-14Ni) has been studied. Results show that with increasing solid solution temperature and extending holding time the amount of 8- ferrite in slab decreases ； with increasing solid solution temperature the network of δ-ferrite in casting slab is broken and coarsened ； air cooling promotes the grown 8-ferrite at higher temperature transforming to smaller granular structure

and as casting slab sample solid solution treats at 1 200 ℃ for 3 h and cools in air the network 8-ferrite in slab sample completely transforms to dispersed less than 10 μm granular ferrite structure and the 8-ferrite phase proportion also decreases from 14.3% to 7.3%. Relative to granular ferrite the two phase interface of austenite and ferrite for network δ-ferrite structure is easily to form crack during rolling.