초록 ▼

A powder metallurgical process for producing dense low-alloy ferrous parts having selected carburized surface portions in which a metal powder of the desired composition is briquetted into a shape-retaining preform, the preform is masked, sintered, carburized whereafter the mask is removed and the r

A powder metallurgical process for producing dense low-alloy ferrous parts having selected carburized surface portions in which a metal powder of the desired composition is briquetted into a shape-retaining preform, the preform is masked, sintered, carburized whereafter the mask is removed and the resultant preform is forged to a desired final shape. The forged part is then quenched immediately following the forge operation for hardness or if desired it can be further heat treated in another manner to obtain other mechanical properties.

대표청구항 ▼

A process for obtaining a substantially fully dense, selectively and partially carburized, low-alloy ferrous, powder metal part comprising the sequential steps of: a. briquetting a low-alloy ferrous metal powder preform having a fixed uniform initial carbon content throughout both the case and inner

A process for obtaining a substantially fully dense, selectively and partially carburized, low-alloy ferrous, powder metal part comprising the sequential steps of: a. briquetting a low-alloy ferrous metal powder preform having a fixed uniform initial carbon content throughout both the case and inner core thereof, the briquetted preform having at least one first surface portion thereof which in the final forged form is required to be of a certain case depth and having at least a second surface portion which in final forged form is to be substantially uncarburized, b. sealing said at least one second surface portion from the carburizing atmosphere by applying masking means substantially completely enclosing in sealing engagement said at least one second surface portion, said masking means comprising a metal member having surfaces which interfittingly engage said preform to isolate selected regions thereof from its surroundings, c. sintering said preform, d. carburizing said preform to substantially increase the initial carbon content thereof in said case by providing a controlled carbon atmosphere of rich endothermic gas and maintaining said preform in said controlled atmosphere for a predetermined period of time sufficient to obtain a desired case depth of final carbon content at said at least one first surface portion substantially greater than said initial carbon content of the case as well as the final carbon content of said inner core and said at least one second surface portion, e. removing said masking means from said preform, and f. forging said preform.