FIELD OF INVENTION
This invention relates to a Direct-Forging Process for the production of iron phosphorus (Fe-P) based magnetic laminations. Specifically but without implying any limitation there-to the invention relates to production of Fe-P, Fe-P-Si and Fe-P-Cr magnetic laminations with phosphorus content in the range of 0.01% to 1.5%.
PRIOR ART
Fe-P sintered alloy components containing around 0.4% Phosphorus are commercially developed for soft magnetic applications in electrical and electronic machines, equipment and devices. These are thick single piece components and higher than 0.4% P content in the alloy results in excessive dimensional shrinkage associated with sintering process. However, it has been established that magnetic characteristics and strength both increase with increase in phosphorus content in the alloy, Fe-P based high density laminations are not known in the art so far. Even higher phosphorus than 0.45% P in these alloys pose difficulty in forming owing to the limitations of compaction and sintering process as stated above. Thin laminations of such alloy have lower energy losses in transformer applications.
Fe-P alloys are therefore known in the art to be prepared by cold compacting and sintering alone. However, there is no process for preparation of Fe-P based alloys by direct forging route. The present invention has evolved this

Yet further object of the present invention is to propose a process for the production of Fe-P based magnetic materials, which overcomes the forming problems of hot/cold shortness which adversely affect the magnetic properties of these materials.
Even further object of the present invention is to propose a process for the production of Fe-P based magnetic materials wherein the process offers flexibility in alloy designing to suit specific application oriented magnetic and electrical properties.
STATEMENT OF INVENTION
According to this invention there is provided a Direct-Forging Process for the production of iron phosphorus (Fe-P) based magnetic laminations particularly Fe-P, Fe-P-Si and Fe-P-Cr laminations having 0.0.1-1.5%P, 0.0-2.0 Si ,or 0.0-0.5%Cr wherein the process comprises steps of:
(a) preparation of Fe-P powder mix by mixing commercially available iron powder, and Fe-P master alloy for production of Fe-P alloy and additionally a material selected from Ferro-silicon and Ferro-Chrome powder for production of alloy Fe-P-Si, Fe-P-Cr respectively; taking 0.4% to 60.0% of Fe-P master alloy containing 2.5%P and balance commercial iron powder for production of Fe-P alloy and additionally 0.1% to 2.78% of Fe-Si containing 72% Si, and 0.1% to 0.78% Fe-Cr powder containing 64% Cr; wherein quantities of ingredients would change accordingly when the said Fe-P master alloy, Fe-Si alloy and Fe-Cr alloy have phosphorus, Si and Cr content other than 2.5% P, 72% Si and 64% Cr respectively,

(b) hot forging the powder mix thus obtained by step (a) by encapsulating
in a mild steel tube, passing dry hydrogen gas and heating at
temperature of 1000 to 1050°C,
(c) homogenizing the hot forged slab obtained by step (b) by heating at
1050-1350°C for 1-2 hours followed by hot pressing and air-cooling,
(d) Subjecting the homogenized sample to hot rolling at 850-1050°C
followed by cold rolling,
(e) subjecting the laminations obtained by step (d) to either annealing at
850-900°C for 20-30 minutes or stress relieving at 850-900°C for 2-5
min, depending upon whether higher magnetic or higher mechanical
properties are required, in the laminations.
DESCRIPTION OF FIGURES
In the accompanying drawings in Fig 1 shows the flow chart of the process of the present invention.
DESCRIPTION OF INVENTION
According to the present invention, Fe-P based magnetic laminations are prepared by the process comprising of:-
(a) Preparation of Fe-P powder mixture

phosphorus from 0-0.7% and Chromium from 0-0.4% by weight are found to possess density in the range of 7.3 gm/cc to 7.5 gm/cc. The tensile strength and elongation for the alloy with 0.35%P and 0.4% Cr (rest is the iron) are 340MN/m2 and 13% respectively. Although the maximum induction for this Fe-P-Cr powder forged alloy at 100'Ωe is only about 9.2 kilogauss. It can be inferred that these alloys have a great potential for use as structural materials in soft magnetic applications.
On the basis of forming characteristics, density, electrical resistivity mechanical and magnetic properties of binary Fe-P and ternary Fe-P-Si and Fe-P-Cr powder forged alloys, it is inferred that these highly dense alloys in the form laminations, may suit to varying requirements for many diversified magnetic applications.

We Claim;
1. A Direct-Forging Process for the production of iron phosphorus (Fe-P) based magnetic laminations particularly Fe-P, Fe-P-Si and Fe-P-Cr laminations having 0.01-1.5%P, 0.0-2.0 Si or 0.0-0.5%Cr wherein the process comprises steps of:
(a) preparation of Fe-P powder mix by mixing commercially available iron
powder, and Fe-P master alloy for production of Fe-P alloy and
additionally a material selected from Ferro-silicon and Ferro-Chrome
powder for production of alloy Fe-P-Si, Fe-P-Cr respectively; taking
0.4% to 60.0% of Fe-P master alloy containing 2.5%P and balance
commercial iron powder for production of Fe-P alloy and additionally
0.1% to 2.78% of Fe-Si containing 72% Si, and 0.1% to 0.78% Fe-Cr
powder containing 64% Cr; wherein quantities of ingredients would
change accordingly when the said Fe-P master alloy, Fe-Si alloy and
Fe-Cr alloy have phosphorus, Si and Cr content other than 2.5% P,
72% Si and 64% Cr respectively,
(b) hot forging the powder mix thus obtained by step (a) by encapsulating
in a mild steel tube, passing dry hydrogen gas and heating at
temperature of 1000 to 1050°C,
(c) homogenizing the hot forged slab obtained by step (b) by heating at
1050-1350°C for 1-2 hours followed by hot pressing and air-cooling,
(d) Subjecting the homqgenized sample to hot rolling at 850-1050°C
followed by cold rolling,
(e) subjecting the laminations obtained by step (d) to either annealing at 850-900 °C for 20-30 minutes or stress relieving at 850-900°C for 2-5 min, depending upon whether higher magnetic or higher mechanical properties are required, in the laminations.
2. A process as claimed in claim 1, wherein direct hot forging is carried
out at 1040-1 050°C for 20-40 minutes.
3. A Direct-Forging Process for the production of iron phosphorus (Fe-P)
based magnetic laminations, substantially as described and
exemplified herein.