The carbon in the media will diffuse in microstructure, which not only embrittles the tubes, but also produces the residual stresses on their surface.

• 当炉管长期在高温下工作时,介质中的碳会渗入到显微组织中,这不仅使材料脆化,而且使渗碳表面产生残余应力,导致炉管开裂。