I have the problem during the cooling after forging or rolling, above all in big sizes. I try to cool the bar as low as posible until it can be trasferred to a annealing furnace. But this is a very slow proceess.
DXM;
Are the bars suffering from visual cracks on the OD surface after cooling (quenching)? Sorry, but your post is still not very understandable to me. What is the actual problem with the bar and how are you processing the bar?
The bar is produced by forging of ingot. After forging cooled slowly to atmosferic temperature. There is no quenching.
The crack is big and longitudinal.
DXM;
Now we are getting somewhere. How slow are you cooling after forging is completed? Reference to ASM Handbook on Bulk Forming of 410 stainless steel forgings highly recommends very slow cooling (using an insulting medium) or temperature equalizing in a furnace to at least 1100 deg F because this material is air hardenable (concern is especially with higher carbon containing 410 forgings).
This is one of several possibilities. Next, I would review the chemical composition of the forging to ensure proper chemical specification requirements. Look at sulfur content.
Do these cracks run the full length of the bar? Or are they isolated to specific areas near the hot top end or near the bottom end? What size and shape of ingot are you forging, and what size bars are you making from these ingots? What is the method of furnace heating for forging? Are you ramp heating these ingots, or step heating them? If you are ramp heating them, what is the ramp rate?
