SE378260

1491726 Sintered alloy steels HOGANAS AB 28 Nov 1974 [29 Nov 1973] 51685/74 Heading C7D A powder mixture which is pressed and sintered to form alloy steel articles consists of two powders, (1) an atomized pre-alloyed steel powder, and (2) a finely comminuted powder containing alloying elements, wherein powder (2) contains all of the alloying elements whose oxides have a free energy of formation (#G) of > 120 kcal/mole 02 at 1000‹C (e.g. Cr, Mn, Al, Ti, Si, V) and powder (1) contains substantially all of the alloying elements whose oxides have a #G < 120 kcal/mole 02 at 1000‹C (e.g. Cu, Mo, Ni, Co), the remainder (less than 0.4%) being contained in powder (2). The mixture preferably comprises 80-99 wt. per cent of powder (1) and 1-20 wt. per cent of powder (2). Powder (1) is preferably formed by wateratomization, and powder (2) by cooling and crushing a melt. Powder (2) may contain up to 10%C as alloying element, and up to 1% of graphite and/ or zinc stearate as lubricant. The Examples refer to sintering a mixture of a water-atomized Mo steel powder and a ferro alloy containing Mn and Cr (Example 1), and mixtures of a water-atomized steel containing Ni and Mo, and Fe-Cr (Example 2).