What material is used for the inner frame of the paving bricks? Is it 16MnCr5 (German board) or Q355B (domestic board)? Can both achieve a carburizing strength of 58-62 HRC? According to information found on Chatgpt, the former can achieve a carburizing strength of 58-62 HRC, but the latter is around 55-60 HRC. If a customer inquires, it will cause distrust and doubt.