EP0380630B1

EP0380630B1 - Use of a high damping capacity, two-phase fe-mn-al-c alloy

Info

Publication number: EP0380630B1
Application number: EP89908610A
Authority: EP
Inventors: Chi-Meen Wan
Original assignee: Famcy Steel Corp
Current assignee: Famcy Steel Corp
Priority date: 1988-07-08
Filing date: 1989-07-06
Publication date: 1994-11-30
Anticipated expiration: 2009-07-06
Also published as: JPH03500305A; WO1990000629A1; ATE114736T1; AU3981589A; EP0380630A4; DE68919672D1; AU610429B2; DE68919672T2; EP0380630A1; CA1336364C

Abstract

Carbon steels and other hot-and cold-workable ferrous alloys generally have poor damping capacity as compared to that cast iron (gray cast iron, malleable cast iron and ductile cast iron). This is because the graphite in cast irons helps to absorb the damping force and depresses the damping wave. But cast iron can not be rolled into strip of sheet. By controlling the correlated concentrations of manganese, aluminum and carbon, Fe-Mn-Al-C based alloys are made to be alpha + gamma two-phase alloy steel with different alpha and gamma volume fractions. With particular ferrite volumes, workable Fe-Mn-Al-C based alloys have equivalent and better damping capacity than that of cast irons especially in the high frequency side. Such alloys suppress the vibration noise that comes from machine rooms, motors, air conditioners, and etc. Chromium and other minor amount of elements can be added to this alloy system to improve the corrosion resistance.

Description

This invention relates to a high damping capacity, two-phase Fe-Mn-Al-C alloy.
Previously, alpha-gamma two-phase alloys have been developed by adding molybdenum and cobalt to the Fe-Ni-Cr alloy system for the purpose of making alloys having both better stress corrosion and hydrogen embrittlement resistance. However, none of these alloys was designed for the purpose of higher damping capacity. The iron-based materials that have been used for high damping capacity are the cast irons. The graphite in gray cast irons is the most important factor for absorbing the high frequency vibration wave. But cast irons generally are not workable, making them of limited value in high damping applications.
According to the present invention, there is provided use of a ferrite-austenite two-phase alloy for high damping capacity applications, said alloy having a composition comprising of 10 to 45 wt% manganese, 4 to 15 wt% aluminum, up to 12 wt% chromium, 0.01 to 0.7 wt% carbon and optionally containing 0 to 4.0 wt% molybdenum, 0 to 4.0 wt% copper, 0 to 2.0 wt% nickel, 0 to 3.5 wt% niobium, up to 500 ppm boron, up to 0.2 wt% nitrogen, 0 to 3.5 wt% titanium, 0 to 2.0 wt% cobalt, 0 to 3.5 wt% vanadium, 0 to 3.5 wt% tungsten, 0 to 2.0 wt% zirconium, up to 2.5 wt% silicon, the balance iron and impurities, the composition being such that the ferrite phase of said alloy comprises 25% to 75% by volume of the alloy, the remainder being essentially austenite, said alloy having a damping capacity of about the same level as that of ductile iron.
For a better understanding of the invention, and to show how the same may be carried into effect, reference will now be made, by way of example only, to the accompanying drawings, in which:-

Figure 1 depicts the damping capacity curve for an alloy in accordance with the present invention; and
Figure 2 depicts the damping capacity curve for ductile iron.

In Fe-Mn-Al-C alloys, manganese and carbon are gamma-phase formers and aluminum is an alpha-phase former. By suitable compositional arrangement, Fe-Mn-Al-C alloys can be designed to be fully gamma phase, such as Fe-29Mn-7A1-1C. Reduction of the manganese or carbon or both of them and the increase of aluminum can promote the appearance of alpha phase, and make the alloy an alpha+gamma two-phase steel. The volume fraction of alpha phase can be controlled by changing the amount of manganese or aluminum or carbon or other ferrite-forming elements.

Example 1

This example illustrates the effect of the element compositions on the change of a volume fraction in the Fe-Mn-Al-C based alloys. Manganese and carbon are austenite phase stabilizers and aluminum is a ferrite phase former. The effect of the carbon content on the ferrite fraction of the Fe-Mn-Al-C based alloys is shown in Table I, in which the chemical composition of aluminum and manganese are essentially constant and the carbon content decreases from 0.5 wt% to 0.11 wt%. With the decreasing of carbon content, the ferrite phase volume fractions of the alloys increases from 0% to 36%. With the change of manganese, carbon and aluminum contents, the volume fractions of ferrite phase and balanced γ phase is controlled to be from 25% to 75%. Within this ferrite fraction range, excellent damping capacity is always found in the Fe-Mn-Al-C based alloy. Table I

composition alloy No. Mn (wt%) Al (wt%) C (wt%) ferrite vol%

1 26.0 7.4 0.5 0

2 26.3 7.6 0.34 11.9

3 25.8 7.4 0.11 36.0

Example 2.

This example illustrates the good damping capacity of the said α + γ two-phase Fe-Mn-Al-C based alloys which have been measured and determined with comparison to ductile cast iron. The test sample of the invention contained 19.7Mn-5.84Al-5.74Cr-0.19C. The ferrite volume fraction is about 65% balanced with γ phase. The damping capacity curves of the damping capacity tests of the Fe-Mn-Al-C based alloy and ductile cast iron are shown in Fig. 1 and Fig. 2. It is seen that the damping capacities of the two alloys are almost equivalent.

Example 3.

This example illustrates the good workability of α+γ two-phase Fe-Mn-Al-C based alloys. The alloys listed in Table II were cast into ingot; homogenized at 1200°C; cut and hot forged at 1200°C; further annealed at 1150°C and descaled. The alloys were cold rolled into 2.0 mm thick strip and annealed. The ferrite volume percentages of these strips were measured and are listed in Table III. The mechanical properties of these annealed strips are also listed in Table III. It is seen that the alloys of the invention have good workability and excellent mechanical properties.

Table II

alloy no.	Mn	Al	C	Cr	Other
#109	25.1	6.7	0.287	5.6	200ppmN₂
#108	30.3	6.3	0.244	5.8	----
#320	21.6	6.8	0.11	0	----
#317	20.0	6.1	0.4	5.5	0.92Mo
#129	33.4	10.3	0.47	2.1	0.2Ti
#116	29.5	10.2	0.4	0	0.1Nb

Table III

sample no.	0.2% proof stress (ksi)	ultimate tensile stress (ksi)	% elongation	hardness (Rb)	ferrite %
#109	45	103	42	84	45
#108	39	94	44	80	28
#320	41	98	43	82	67
#317	44	101	41	83	75
#129	61	112	38	86	65
#116	59	109	37	85	73
1 ksi = 6.895 MPa

Claims

Use of a ferrite-austenite two-phase alloy for high damping capacity applications, said alloy having a composition comprising of 10 to 45 wt% manganese, 4 to 15 wt% aluminum, up to 12 wt% chromium, 0.01 to 0.7 wt% carbon and optionally containing 0 to 4.0 wt% molybdenum, 0 to 4.0 wt% copper, 0 to 2.0 wt% nickel, 0 to 3.5 wt% niobium, up to 500 ppm boron, up to 0.2 wt% nitrogen, 0 to 3.5 wt% titanium, 0 to 2.0 wt% cobalt, 0 to 3.5 wt% vanadium, 0 to 3.5 wt% tungsten, 0 to 2.0 wt% zirconium, up to 2.5 wt% silicon, the balance iron and impurities, the composition being such that the ferrite phase of said alloy comprises 25% to 75% by volume of the alloy, the remainder being essentially austenite, said alloy having a damping capacity of about the same level as that of ductile iron.