Weld on Hubs

[smokeshow]

Anyone use A2 tool steel for weld on hubs? I got a few slabs for cheap. Im worried about it being too hard after welding.
 

[forty40]

In the interest of your safety and those associated with a pulling tractor, it is not recommended to use tool steel welded on hub adaptors. Welding tool steel in any dynamic application would not be recommended nor permitted by any code or specification, even if the entire assembly were completely re-heat treated and is asking for trouble. The carbon percent is high, 1.0%, then add the alloying elements of 0.6 Mn, 5.3 Cr, 1.1 Mo, and 0.2 V which brings the carbon equivalent, subsequent hardness, and crack sensitivity near that of arc welding cast iron. Normal steel with carbon % higher than .30 is considered enough to use a minimum of 175 deg F preheat and many application over 5/8” T require PWHT. Maybe luck would be involved and nothing would happen but the risk for catastrophic failure is much higher that could safely be recommended. Should a failure with injury occur, the insurance metallurgical investigation would readily show a lack of sound welding practice and the liability assessment would be astronomical.
Dave Miller
Sr. Welding Engineer, Dresser-Rand