As you heat the part it will begin to turn a straw color. Carbon Fiber HTPLA can make very accurate parts particularly when heat treating, demonstrating less distortion of form and dimension change after heat treating compared to other HTPLAs. [Hardenability is a direct function of carbon content in this case]. Fire extinguisher. can be accommodated. Heat Treat Ovens and Accessories. Image on the flat screen is a polished and etched, through hardened, medium carbon, manganese-chromium alloy steel transverse section (cut perpendicular to steel rolling direction). …