Master alloy for producing sinter hardened steel parts and process for the production of sinter hardened parts

1. A master alloy for sinter hardened steel parts, the master alloy comprising a composition of

iron;

at least 4.5 to less than about 7 weight % C in the master alloy,

5.39 to less than about 20 weight % Mn in the master alloy,

5.40 to less than about 20 weight % Cr in the master alloy,

no Si, with the exception of Si possibly present as an inevitable impurity,

no Ni, with the exception of Ni possibly present as an inevitable impurity,

wherein the master alloy is in the form of water atomized particulates having a total oxygen content below about 1 weight %, and

wherein the master alloy comprises a microstructure including a mixture of austenite and cementite and the austenite microstructure is composed of a solid solution of the manganese, chromium, and carbon, the microstructure comprising at least 60 volume % austenite;

wherein the carbon is pre-alloyed in the master alloy, and the hardness of the master alloy is less than 900 Vickers.

2. The master alloy of claim 1 , wherein the particulate size of the water atomized particulates is controlled by atomization and grinding.

3. The master alloy of claim 1 , wherein the water atomized particulates have a d 50 from 5 μm to 30 μm and a d 90 from 20 μm to 60 μm.

4. The master alloy of claim 1 , wherein the composition further comprises less than 10 weight % Mo in the master alloy.

5. The master alloy of claim 1 , wherein the composition further comprises less than 10 weight % Cu in the master alloy.

6. The master alloy of claim 1 , wherein the composition further comprises less than 5 weight % V, less than 5 weight % W, less than 5 weight % Nb, less than 1 weight % P, less than 0.1 weight % B in the master alloy, and wherein the remainder of the composition is iron and inevitable impurities.

7. The master alloy of claim 1 , wherein the master alloy comprises at least 60 weight % of iron.