| 摘要 |
PURPOSE:To provide a satisfactorily carburization-hardened material which is free from intergranular cementite precipitation by subjecting the material to be carburization-hardened in a nonoxidative atmosphere chamber to high-temp. carburization with the high frequency in the carburizing atmosphere chamber then to diffusion by heating with the high frequency in the nonoxidative atmosphere chamber and cooling quickly said material. CONSTITUTION:A sealing plate 11 is opened and a material 1 to be carburization-hardened in a feed chamber 2 into which nonoxidative gaseous nitrogen 5 is blown is put by a rotating work lift 9 into a chamber 3 into which nitrogen contg. hydrocarbon is blown 14. Said material is quickly carburized and heated to about 1,100 deg.C by a high frequency coil 12. The carburized material 1 is put by the lift 9 into a chamber 4 into which nonoxidative nitrogen is blown 18. Said material is maintained at the same temp. as the temp. for carburization by a high frequency coil 16 and is thus subjected to diffusion. Said material at said temp. is pushed by an air cylinder 20 and is charged into a hardening vessel 21 where the material is hardened. The material is quickly carburized by the high frequency carburizing and heating and since the oxygen potential is low, there is no precipitation of intergranular cementite. |
