Fe-Cr-Ni alloy for wear-resistant loom parts

An Fe-Cr-Ni alloy used for parts of an automatic loom such as a heald (7) and reed (12) consisting of from 13 to 20% of Cr, from 4 to 15% of Ni, the balance being Fe and unavoidable impurities, and having a microstructure that is 60% or more strain-induced martensite. Wear resistance of the parts is improved, so that neither fluff nor rupture of yarn occurs during loom operation.

BACKGROUND OF INVENTION 
1. Field of Invention 
The present invention relates to an Fe-Cr-Ni alloy useful for a part of an 
automatic loom as well as a wear-resistant part of an automatic loom. More 
particularly, the present invention relates to an Fe-Cr-Ni alloy with 
improved wear-resistance against yarn. 
2. Description of Related Arts 
Parts of an automatic loom, which are brought into contact with yarn, 
include a reed and a heald as described below. 
Referring to FIG. 1, a plurality of neck yarn 2 is moved upward or downward 
according to the information in a Jacquard paper, by means of a Jacquard 
driving mechanism 1. A plurality of harness cords 3 are connected to the 
lower ends of the neck cord and pass through a plurality of apertures 5 of 
a comber board 6. The lower ends of the harness cords 3, which pass 
through the comber board 6, are secured to a heald 7. The weft (not shown) 
pass through the apertures 7a of the heald 7. The heald 7 lifts up 
successively and vertically displaces the weft. As a result, a reed hole 
is formed between a number of wefts and allows a shuttle, in which warps 
are mounted, to pass therethrough. Restoring springs 8 are connected to 
the bottom of the heald 7 at one end thereof and a the fixing bed 9 at the 
other end. 
Referring to FIG. 2, a reed apparatus 10 is located in front of the heald 7 
and comprises a reed chamber 11 in the form of a trapezoidal frame and 
reed wires 12. Warp 16 passes through between the reed blades 12 and then 
through the apertures 7a of the heald. 
Conventionally, the reed 12 and heald 7 are made of a hardsteel sheet or 
hard-steel wire. The reed 12 and heald 7 are replacable parts liable to 
wear out due to sliding contact with the yarn. When these parts wear out, 
minute grooves, referred to as yarn passes, are formed on the parts with 
the result that such anomalies as fluff and rupture of yarn arise. 
Operation of an automatic loom will thus be interrupted or its parts must 
be replaced by new parts, resulting in inconvenience in the operation of 
the automatic loom. In the worst case, defects are formed on the product. 
Furthermore, along with an increase of speed of newer automatic looms, 
their parts are brought into contact with much longer length of yarn as 
compared with conventional looms. 
Accordingly, fluff and yarn ruptures occur in very short periods of 
operation that would not occur in a conventional automatic loom. Level of 
wear-resistance required for parts of an automatic loom have become 
therefore more stringent than that of conventional parts. In addition, 
since new textile materials have been developed, the parts of an automatic 
loom must exhibit wear-resistance against such materials also. 
SUMMARY OF INVENTION 
Mere increase in hardness of parts of an automatic loom cannot successfully 
prevent the fluff and yarn rupture due to the formation of yarn passage on 
such parts. 
It is an object of the present invention to provide an Fe-Cr-Ni alloy which 
has a microstructure capable of improving wear-resistance against yarn. 
It is also an object of the present invention to provide a sliding part 
having highly enhanced wear resistance with respect to yarn. 
In accordance with the objects of the present invention, there is provided 
an Fe-Cr-Ni alloy for use as a part of an automatic loom, which part will 
be in sliding contact with yarn, characterized in that the Fe-Cr-Ni alloy 
consists of, by weight percentage, from 13 to 20% of Cr, from 4 to 15% of 
Ni the balance being Fe and unavoidable impurities, and has a 
microstructure such that 60% or more, preferably 70% or more based on the 
matrix is a strain-induced martensite. 
In accordance with the objects of the present invention, there is provided 
a part of an automatic loom, which part will be in sliding contact with 
yarn and consisting of the Fe-Cr-Ni alloy mentioned above.

DESCRIPTION OF PREFERRED EMBODIMENTS 
The Fe-Cr-Ni alloy according to the present invention exhibits an 
exceedingly high wear-resistance against yarn sliding thereon at a high 
speed, so that the fluff and rupture of yarn can successfully be 
minimized. Corrosion resistance of the Fe-Cr-Ni alloy is excellent. The 
inventive alloy has excellent formability to be shaped into parts of an 
automatic loom. 
The alloying components of the Fe-Cr-Ni alloy according to the present 
invention are first described. 
Cr: The parts of an automatic loom are required to have corrosion 
resistance because the automatic loom is used under various circumstances. 
For example, parts may come in contact with water which is used in some 
types of automatic looms. The corrosion resistance of Fe-Cr-Ni can be 
attained by adjusting the Cr content within an appropriate range. When the 
Cr content is less than 13%, the corrosion resistance is poor. On the 
contrary, when the Cr content is more than 20%, the formability of the 
Fe-Cr-Ni alloy is impaired. The Cr content is therefore from 13 to 20%. A 
preferred Cr content is from 15 to 19%. 
Ni: Ni contributes to improving the corrosion resistance as does Cr. When 
the Ni content is less than 4%, the corrosion resistance is impaired. In 
addition, when the Ni content is less than 4%, since Ni is an 
austenite-former, the austenite phase is formed with difficulty. It then 
becomes then difficult to induce the required amount of martensite phase 
by means of working. On the other hand, when the Ni content is more than 
15%, since Ni is an austenite-stabilizing element, the required amount of 
strain-induced martensite becomes difficult to obtain. In addition, the 
materials costs are increased when the Ni content exceeds 15%. The Ni 
content is therefore from 4 to 15%. A preferred Ni content is from 5 to 
13%. The elements other than those mentioned above, such as C, P and S are 
detrimental to the corrosion resistance. Such elements other than the 
above mentioned ones such as Mn, Al and Si are incidental elements which 
are not particularly effective for attaining the objects of the present 
invention. These elements are inevitably included in the Fe-Cr-Ni alloy as 
impurities, when the alloy is produced by melting the ordinary 
raw-materials. The content of the impurities is preferably not more than 
3.5% in total amount. 
It was discovered by the present inventors that the wear resistance of an 
Fe-Cr-Ni alloy with respect to yarn is greatly dependent upon the amount 
of the strain induced martensite, even though the composition and hardness 
of the Fe-Cr-Ni alloy remains constant. For example, when an Fe-Ni-Cr 
alloy (A) having a strain induced martensite of 50 %, an austenite of 50%, 
and hardness Hv of 500 is compared with an Fe-Cr-Ni alloy (B) having the 
same composition as alloy (A) and having a strain induced martensite of 
60%, an austenite of 40%, and hardness of Hv=500, the wear resistance of 
(B) is better than that of (A). 
Since the desired wear resistance is not attained by a strain induced 
content of less than 60%, its weight percentage is specified to be 60% or 
more. A preferred amount of the strain induced martensite is 70% or more. 
The strain induced martensite herein indicates that a complete austenitic 
structure is once formed and is then subjected to working to induce the 
martensitic transformation in order to convert the gamma phase to an alpha 
phase. The complete austenitic structure means that the essential elements 
of the present invention, i.e., Fe, Cr and Ni, form an austenitic matrix, 
and, further, the impurities are present in the form of minority phases 
such as carbides and sulfides. The minority phases should be present in 
such a trace amount that the presence exerts an influence upon the 
measured valued of the strain induced martensite only within a range of 
measurement error. The amount of strain induced martensite is obtained by 
applying external density with an intensity of 199000 A/m (i.e., 2.5 kOe) 
to an Fe-Cr-Ni alloy, measuring the magnetic flux density B (T), 
multiplying the magnetic flux density with 100 (i.e., the result) and 
dividing 100B by 1.6 T. 
The Fe-Cr-Ni alloy and a part of an automatic loom according to the present 
invention can be produced by the following process. 
The alloying components satisfying the above mentioned range are melted, 
cast and subsequently subjected to hot-forging or rolling. The wrought 
product is, if necessary, subjected to solution heat-treatment. 
Cold-rolling and subsequent annealing are carried out at least once. 
Finally, the cold-rolling, which induces martensitic transformation, is 
carried out, while reducing the thickness from to 0.1 down to 0.3 mm. The 
obtained rolled sheets are blanking worked by means of, for example, a 
press machine, to provide the shape for parts of an automatic loom. In the 
case of producing a wire, a process similar to that used in producing a 
sheet is carried out. 
The present invention is hereinafter described by way of an example. 
EXAMPLE 
The alloys having a composition as shown in Table 1 were melted and cast 
into ingots. The ingots were then hot-rolled to form 3 mm thick sheets and 
then solution heat-treated at 1050.degree. C. for 30 minutes. The 
resultant structure was completely austenitic. The 3 mm thick hot-rolled 
sheets were cold-rolled at a reduction of from 50 to 90% and then annealed 
at 1050.degree. C. This cold-rolling and subsequent annealing were in some 
cases repeated twice. The resultant 0.3 mm thick sheets had hardness of Hv 
540 and various amounts of strain induced martensite. 
In order to investigate the wear resistance of the obtained materials, 
samples having a width of 10 mm were taken. Twenty four filaments with 75 
denier were suspended from the sample and a tension of 30 gram was applied 
to the filaments. The filaments were caused to slide on the sample at a 
speed of 40 cm/minute. The worn of portions of the samples brought into 
contact with the filaments were observed. The results are shown in Table 
1, below. 
TABLE 1 
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Chemical Strain 
Composition 
Induced State 
(wt %) Marten- Hardness of 
Cr Ni Fe site (%) 
(Hv) Wear 
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In- 1 15.8 5.2 Bal 91 554 Extremely 
ven- Slight 
tive 2 16.3 6.5 Bal. 85 663 Extremely 
Alloys Slight 
3 17.5 7.2 Bal. 73 570 Slight 
4 18.2 5.8 Bal. 76 542 Slight 
5 18.8 6.1 Bal. 62 557 Slight 
6 16.4 6.8 Bal. 77 558 Slight 
7 17.3 5.7 Bal. 84 561 Slight 
Compar- 
8 16.0 6.2 Bal. 63 557 Medium 
ative 9 17.6 5.9 Bal. 48 542 Great 
Alloys 10 16.4 6.0 Bal. 55 568 Medium 
11 18.4 7.6 Bal. 41 540 Great 
12 17.8 6.5 Bal. 50 546 Great 
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Criterion for judging the wear was as follows. 
Great: clear yarn marks and fluff were recognized. 
Medium: clear yarn marks were recognized. 
Slight: some yarn marks were recognized. 
Extremely slight: very slight yarn passage was recognized. 
As is clear from Table 1, although the hardness of the inventive examples 
is approximately the same as that of the comparative samples, the wear of 
the former from yarn is less than that of the latter. The wear resistance 
is therefore improved by the present invention.