cracks in 52100

[blacktailforge]

does anybody know why I'm getting tiny squiggly cracks in 52100 after forging? Am I letting temp get too cool?

 

[D.Crawford]

From Kevin Cashen:

"Recommended Working Sequence For 52100

Forging: Heat to 2100 °F (1150 °C) maximum, and do not forge after temperature of the forging stock has dropped below approximately 1700 °F (925 °C)

Normalizing: Heat to 1625 °F (885 °C) and cool in still air.

Annealing: For a predominately spheroidized structure which is generally desired for machining, heat to 1460 °F (795 °C) and cool rapidly to 1380 °F (750 °C), then continue cooling to 1250 °F (675 °C) at a rate not exceeding 10 °F (6 °C) per hour; or as an alternative technique, heat to 1460 °F (795 °C), cool rapidly to 1275 °F (690 °C) and hold for 16 hours.

Grinding or Machining

Hardening: Austenitize from 1475°F to 1550 °F (845 °C) and quench in oil. Lower austenitizing temperatures may be used depending upon the previous thermal treatments and resulting carbide conditions. If higher temperatures result in excess carbon in solution, retained austenite can become problematic.

Tempering: As-quenched hardness as high as 66 HRC. After quenching, parts should be tempered as soon as they have uniformly reached near ambient temperature."

 

[Rick Marchand]

You are forging too cold, my friend. Unfortunately, cracks are not fixable.

 

[mete]

Would be nice if you gave us photos of the cracks.

 

[blacktailforge]

Would be nice if you gave us photos of the cracks.

will get some pics soon, but I think rick is right although I do try to keep temp up while forging.

 

[mete]

The proper terms are 'hot short' for brittle at higher temps and 'cold short' for brittle when cool. Remember that each steel is different and must be handled with there own characteristics.