In order to evaluate the joining between steels and the powder rolling sheets, the bonding conditions considering the role of the porosity, were investigated as functions of sintering temperature, sintering time and bonding pressure under the condition of dissociated ammonia gas atmosphere. Results obtained were as follows:
(1) As a constant sintering time, the tensile strength of the joints increased at elevated bonding pressure. However, no particular change was recognized for the hardness of crystalline in the matrix phase.
(2) The growth of crystallines and the increasing of pores between graphite and matrix phase were restrained with increasing the bonding pressure.
(3) During tensile test, the specimens were broken outside the joint area in cases of sintering temperatures of 1150 K, 1200 K and 1250 K at the bonding pressure of 0.15 MPa. The increase of temperature and time during the sintering reduced porosities in the contact area, and in addition, the extension of diffusion layers were observed by EPMA.