NO169398B - PROCEDURE FOR PERMANENT SUMMARY OF TWO CONSTRUCTION PARTS THROUGH USING AN ADJUSTABLE MOUNTING DEVICE, AND AN APPLICATION FOR USING THE PROCEDURE - Google Patents

Abstract

A method for joining two structural members by the aid of an ajustable fastening means (6), with said structural members consisting of a door or window frame (15) on one side and a surrounding stationary building structure (18) on the other side, which building structure (18) is displaced relative to said frame (15). The frame comprises a through hole, which is completely or partly threaded, and which comprises a threaded and, thus, adjustable fastening means (6) having a through hole (10) in its longitudinal direction, and which at one end projecting from the frame may be provided with a stop (12) for a screw head or the like. The mounting used is a disk (1) with cut-outs (2, 3) for passing through screws or the like to be attached with the building structure (18) and the disk (1) comprises in its end, which partly or completely projects from said building structure, a fastening member (4, 5) for the adjustable fastening means.

Description

Iron-nickel-chromium-molybdenum alloys.

There are many metals and alloys wherever you want

to achieve resistance to the corrosive effect of chlorides, including salt solutions, strongly oxidizing chloride solutions and sea atmosphere and sea water. The need for alloys that are resistant to such corrosion has increased significantly due to recent developments, e.g. in the area of desalination and seabed mining and drilling.

Metals and alloys commonly used for these purposes include austenitic stainless steels, carbon steels and alloys

steel, copper and copper alloys, including various types of brass, nickel alloys, titanium and titanium alloys. Depending on the particular application, however, these materials have one or

several disadvantages. E.g. austenitic stainless steels, such as AISI steels 304, 310 and 316 are easily machined and cost relatively little, but they have insufficient resistance to crevice corrosion. This disadvantage is even greater in carbon steel and low-alloy steels. Copper alloys and austenitic stainless steels are easily corroded when immersed in seawater that is still or flowing at a velocity less than about 1.5 m per second This increased fouling and corrosion when the velocity of seawater in which they are immersed decreases is characteristic of many materials.

Certain nickel alloys have been used extensively in such environments. One of the most used alloys contains approx. 17% chromium, 16% molybdenum and 4% tungsten; this alloy is expensive, partly because it is difficult to process and usually requires several annealing treatments during processing.

Titanium and titanium alloys are relatively expensive and certain titanium alloys corrode drastically.

The corrosion problem becomes further complicated as the alloys for certain applications should be resistant to chloride attack in the annealed state, while for other applications e.g. for submarine cables, it is more important that they both have a high strength and an exceptionally high resistance to chloride corrosion in the cold-rolled state.

The present invention relates to alloys which are cheap, can be hot and cold worked and which have an increased resistance to surface corrosion, crevice and intergranular corrosion and stress-corrosion cracking in chloride environments, and which can be used both in the annealed and in the cold-rolled state.

The essential components of alloys according to the invention are iron, nickel, molybdenum and chromium, and the alloys contain, by weight, 20-30% nickel, 6-10% molybdenum and 14-21% chromium. within these areas, the content of these three elements must be interdependent, and as, moreover, the properties of the alloys vary with the composition, suitable narrower areas should be chosen for each desired combination of properties.

The attached drawing shows the correlation between nod-

nickel and the molybdenum content. All alloys according to the invention have a nickel and molybdenum content that is mutually dependent and lies within the range BKJONDCB. In addition, the chromium content is at least 18% when the molybdenum content does not exceed 6.5%, and the chromium content is not greater than 20% when the molybdenum content is approx. 10%.

The nickel content of alloys must be at least 20%, as a lower content does not provide sufficient corrosion resistance and also causes the formation of delta ferrite. Even small but excessive amounts of delta ferrite can cause brittleness and poor machinability. For this reason, the alloys should consist of a single phase and be essentially austenitic and free of harmful phases, such as delta ferrite and sigma phase.

If the alloys are to have an optimal combination of resistance to crevice corrosion and good machinability, it is advantageous that. the nickel content is at least 23% and preferably at least 25%.

Very satisfactory results are not always achieved when the nickel content is in the lower part of the permitted range,

i.e. 20-2 3% nickel. Then the alloys have a lower resistance to crevice corrosion, especially in the cold-rolled state, if both the molybdenum-kg worm content is at the lower end of the respective ranges.

Low molybdenum contents result in less resistance to crevice corrosion. The molybdenum content must be at least 6% and even molybdenum content from 6 to 6.5% is insufficient when the chromium content is lower than 18%. In this molybdenum range, the chromium content is preferably at least 18.5%. Even when the molybdenum content is above 6.5

up to 7.5%, the chromium content must generally be greater than 17%, especially with a low nickel content. When the molybdenum content is from 7.5 to 8%, a chromium content of at least 15.5 or 16% is desirable. However, by using 8% or more molybdenum, especially when the chromium content is at least 17%, very satisfactory results can be obtained at higher nickel content. Nickel content above 30% increases costs unnecessarily.

The chromium gives the alloys corrosion resistance, but excessive amounts of chromium can lead to poor properties, particularly as it causes the formation of a multiple-phase structure, and consequently the chromium content must not exceed 21%.

The alloys may contain other constituents, one of which is cobalt in an amount of up to 1%.

In order to achieve very satisfactory properties, it is advantageous that all alloys according to the invention contain calcium, the amount of which can be up to 0.15%. Preferably the alloys contain at least 0.001% and preferably at least 0.01% calcium. Calcium gives the alloys a significantly better resistance to crevice corrosion both in the annealed and in the cold-worked state. Calcium is particularly advantageous for alloys in the cold-worked state and for alloys in which the molybdenum content does not exceed 7.5%. At least 0.001% calcium must be present in alloys containing no more than 7.5% molybdenum, and it is very advantageous that the molybdenum content does not exceed 7.5%. At least 0.001% calcium must be present in alloys containing no more than 7.5% molybdenum, and it is very advantageous that the molybdenum content does not exceed 8%, as resistance to crevice corrosion decreases in its absence even in the annealed state. Preferably, the calcium content of the alloys is 0.001 to 0.1%.

Calcium can be completely or partially replaced with magnesium. The alloys may also contain 0 to 0.2% carbon, 0 to 0.5% silicon, 0 to 1% manganese, the sum of the manganese and silicon content not exceeding 1.25%, 0 to 0.7% titanium, 0 to 0 .7% aluminum, 0 to 2% niobium, 0 to 1% vanadium, 0 to 1% copper,

0 to 1% tungsten and 0 to 2% tantalum. The rest except impurities iron.

The silicon and manganese content must be carefully regulated. The silicon content must not exceed 0.5%, as larger amounts have a detrimental effect on the heat-workability and weldability. The silicon content preferably does not exceed 0.25%. The manganese content must not exceed 1%. Higher manganese content causes a reduction of

the corrosion resistance. The manganese content preferably does not exceed 0.5%. The sum of the manganese and silicon contents must not exceed 1.25% and preferably not exceed 0.75%.

Although the amount of carbon in the alloys can be as high as 0.2%, increasing the carbon content above 0.1%, e.g. to 0.15%, a reduction in crevice corrosion resistance. In order to achieve a good resistance to both crevice corrosion and intergranular corrosion, it is advantageous that the carbon content does not exceed 0.05% or even 0.03%. However, carbon amounts of up to 0.1% are perfectly satisfactory if niobium is present to combine with carbon. The presence of niobium also makes a solution heating of welding pieces redundant.

Titanium and aluminum provide a particularly satisfactory hot workability. The alloys can be air-melted, thereby lowering their price, and under these circumstances the presence of both aluminum and titanium is very advantageous. Titanium stabilizes nitrites and thereby prevents the formation of pores in blocks. It is therefore preferred that at least one and preferably both metals aluminum and titanium are present in amounts of from 0.1 to 0.25 to 0.5% of each of them. Excessive amounts of these elements, e.g. 1.5% or more, are very disadvantageous as they reduce the hot workability without having a beneficial effect on the corrosion resistance.

Phosphorus, oxygen or sulfur present as pollutants should be kept to the lowest possible value. Sulfur is particularly harmful and must be carefully regulated. Nitrogen, which constitutes another pollutant, should be kept below 0.03% and preferably below 0.01%.

During the production of alloys, any added aluminium, titanium or calcium will usually not be fully recovered in the alloy. If it e.g. if a titanium or aluminum content of 0.15% is needed in alloys, 0.25% of the element should be added to the smelting. Calcium, which can be introduced in the form of a calcium-silicon addition, should be added in an amount two or three times greater than the amount ultimately desired in the alloy.

Alloy blocks can be heat worked at temperatures from 1205 to 1260°C and down to 980 and 870°C. The alloys can suitably be annealed at temperatures in the range of 1095 to 1260°C, e.g. 1205°C.

When it comes to the production of such products as strip, the alloys can be hot-rolled, annealed, pickled and cold-rolled. Intermediate annealing between the cold rolling steps can be carried out at temperatures from 1095 to 1205°C.

It is difficult to pick the alloys because of their excellent corrosion resistance.

In the following, some examples are given.

Certain alloys, namely alloys Nos. 1-17 according to the invention and two comparative alloys, R and S, were prepared by air melting. The nominal compositions of these alloys are given in table I. In addition to the elements shown, the alloys nominally contained 0.1% silicon, 0.15% manganese and, with the exception of alloy no. 15, 0.03% carbon. About. 0.06% calcium, as calcium-silicon, and 0.25% titanium and of aluminum were added to the melts. Blocks of the cast alloys were annealed at 1260°C and then hot rolled into ingots, the hot working temperature being 870 to 1260°C.

The hot-rolled alloys were annealed at 1175 to 1205°C for half an hour and then cold-rolled into strips with a thickness of 1.5 mm from a thickness of 6 mm after the hot rolling. The alloys were subjected to corrosion tests in a corrosive agent which is usually used for experimental purposes, namely in a 10% ferric chloride solution. Samples of the alloys were examined both in the cold rolled and in the annealed state. Cold-rolled samples with a surface of 25 cm^ were immersed in approx. 72 hours in the 10% ferric chloride solution. Rubber bands were wrapped around the samples to create cracks. The experiment is considered equivalent to an exceptionally long exposure to seawater. Other cold-rolled samples with the same surface size were annealed at 1175 to 1205°C for half an hour and then examined in the same manner as the cold-rolled samples.

The results of corrosion tests expressed in weight loss in mg

are also given in Table I.

The alloys should not show a weight loss greater than 15 mg and preferably 10 mg in the test with 10% ferric chloride. A weight loss of less than 5 mg is excellent. From the results in Table I, it thus appears Hart that the alloys 1-14 had a very satisfactory resistance to crevice corrosion. No surface corrosion was observed.

Alloy No. 15 contained 0.15% carbon as the composition

was otherwise the same as that of alloys no. 2 and 3. While the

ring No. 15 was satisfactory for casting and for use in annealing

that condition, the high carbon content causes a relatively high weight loss in case of crevice corrosion.

Although the resistance to crevice corrosion of alloys

No. 16 and 17 was good, it was a little difficult to heat treat these alloys. The alloys R and S were more difficult

which contained only 20% nickel and edge cracking was constant with these alloys. However, alloys No. 7 and 11 had

which had the same chromium content and molybdenum content, but a nickel content of over 2 3%, namely 25%, a good hot workability.

In further tests, both cold-rolled and annealed samples were

of alloys 3, 10 and 14 exposed to seawater at ambient temperature which flowed at a speed of 60 cm per second. Specimens were examined to determine crevice corrosion and U-bent specimens to determine stress corrosion cracking. Alloy No. 3 was subjected to the test for 430 days and the other alloys for 300 days, the tests being carried out periodically. All samples were free of signs of stress corrosion cracking. A very small and insignificant crevice corrosion was constant in the cold-rolled test

ve of alloy No. 3 after 90 days, but the corrosion did not progress further and it is possible that the machining prior to the corrosion test was not perfect. In general, the samples behaved very strangely.

For the sake of comparison, certain additional alloys were

gers outside the invention, namely alloys A to P and four alloys according to the invention, namely alloys 26-29 sub-

tested by means of the ferric chloride test in the same way as the alloys in Table I. The compositions (mainly nominal) of these alloys are given in Table II together with the results of corrosion tests. Unless otherwise stated, the alloys contained no more than 0.03% carbon, 0.1% silicon and 0.15% manganese. No calcium, titanium or aluminum was added to alloys E, F and H to P, or to alloys no. 27, 28 and 29. Experiments were also

performed with samples of commercially produced stainless steels AISI 310 and 316. The results for alloys 3, 5, 9 and 13 are also included in Table II for the sake of comparison.

Table II shows that the alloys A to D with a molybdenum content of only 4% had a poor corrosion resistance despite increasing the nickel content. Alloys E and F are representative of previously known alloys and are free of calcium, titanium and aluminium. The crevice corrosion resistance of these alloys was extremely poor. Alloy G, which had a chromium content of only 16% together with a molybdenum content of only 6%, also had poor corrosion resistance, although it contained calcium, titanium and aluminium. However, alloy 26 according to the invention and with the same nominal composition as alloy G, but with 20% chromium, had a satisfactory corrosion resistance. This shows that when the molybdenum content is lower than 6.5%, the chromium content must be at least 18%. Alloy H had such poor hot workability that corrosion tests in the cold-rolled and annealed state were not carried out. This alloy contained 1.1% silicon and 2% titanium and a high combined silicon and manganese content of 1.8%. In marked contrast to that

are the alloys no. 13 and 9 according to the invention.

No calcium, titanium or aluminum was added to melts of alloys H to P and Nos. 27, 28 and 29. Alloys J to M, 27, 28 and 29 and also alloy No. 5 can be compared. Alloys J, K and L had a poor corrosion resistance both in the cold rolled and in the annealed state. Alloys Nos. 27, 28 and 29 were, however, satisfactory in the annealed state and are therefore within the scope of the invention. It is interesting to compare alloy No. 5 (which contained calcium and also titanium and aluminium) with alloys Nos. 27, 28 and 29. The difference "of results is startling. The standard stainless steels AISI 310 and 316 as well as the known alloys N and P misbehaved during these trials.

The alloys according to the invention have high tensile strengths, e.g. 17,576 kg/cm and more, when they were cold drawn into threads. An alloy containing 25% nickel, 20% chromium, 8% molybdenum and less than 0.04% carbon, the rest iron, had a tensile strength of approx. 18,560 kg/cn<r> as well as good bending and breaking ductility when drawn into wire with a 94% cross-sectional reduction.

Alloys according to the invention can be used for vessels, ship hulls and structures and components used in contact with seawater or sea atmosphere. The alloys are particularly useful for e.g. pumps and parts (including blades and impellers), propellers, tubes, valves, holders, pipelines, including heat exchanger tubes and tube sheets, water tanks, seawater evaporators, including sheets, shafts and marine components, e.g. brake pads, lashers, pulleys, forgings, linings, buoys, floating platforms and oil well equipment.

Other applications of the alloys are equipment for chemical factories

for the treatment of oxidizing acids and salts, and containers and pressure vessels for the storage and transport of various chemicals

scythe. The alloys can be used in conventional factory forms, e.g.

e.g. in the form of plates, strips, bars and rods.

Claims (14)

1. Iron/nickel/chromium/molybdenum alloys with good corrosion resistance, particularly good corrosion resistance equal to for chlorides and chemicals, characterized in that the alloy contains from 20 to 30% nickel, from 6 to 10% molybdenum, the nickel and molybdenum content being in such a mutual ratio that it falls within the range BKJONDCB on the attached drawing, from 14 to 21% chromium, the chromium content being at least 18% when the molybdenum content does not exceed 6.5% and the chromium content not greater than 20% when the molybdenum content is 10%, from 0 to 0.2% carbon, from 0 to 0.5% silicon, from 0 to 1% manganese, the sum of the manganese and silicon content not exceeding 1.25%, from 0 to 0.7% titanium, from 0 to 0.7% aluminium, from 0 to 0.15% calcium and /or magnesium, as calcium or the magnesium content is at least 0.001% when the molybdenum content does not exceed 7.5%, from 0 to 12% cobalt, from 0 to 2% niobium, from 0 to 1% vanadium, from 0 to 1% copper, from 0 to 1% tungsten and from 0 to 2% tantalum, while the rest apart from impurities is iron. 2. Alloy as stated in claim 1, characterized in that it contains from 6 to 6.5% molybdenum and that the chromium content is at least 18.5%. 3. Alloy as stated in claim 1 or 2, characterized in that it contains from 6 to 8% molybdenum and at least 0.001% calcium. 4. Alloy as specified in claim 1, characterized in that it contains at least 23% nickel. 5. Alloy as stated in claim 1, characterized in that the chromium content and the molybdenum content are so mutually matched that at least 15.5% chromium is present when the molybdenum content is 7.5 to 8% and that at least 17% chromium is present when the molybdenum content is 6, 5 to 7.5%. 6. Alloy as stated in claims 1-5, characterized in that the nickel and molybdenum contents are mutually matched in such a way that they fall within the range B K J H B and that it contains from 14 to 20% chromium. 7. Alloy as stated in claim 6, characterized in that the nickel and molybdenum content is such that they fall within the range G K J H G and that it contains from 15 to 20% chromium. 8. Alloy as stated in one of claims 1-7, characterized in that it contains at least 0.001% calcium, preferably at least 0.01% calcium. 9. Alloy as specified in claim 8, characterized in that the calcium content does not exceed 0.1%. 10. Alloy as stated in one of claims 1-9, characterized in that it contains titanium and/or aluminum in an amount of 0.05 to 0.6% of each of these elements. 11. Alloy as stated in claim 10, characterized in that it contains 0.1 to 0.5% of each of the elements titanium or aluminium. 12. Alloy as stated in one of the preceding claims, characterized in that it contains no more than 0.25% silicon and no more than 0.5% manganese. 13. Alloy as stated in one of the preceding claims, characterized in that it contains no more than 0.1% carbon, preferably no more than 0.05% carbon. 14. Alloy as stated in one of the preceding claims, characterized in that it contains no more than 0.1% carbon and small amounts of niobium in an amount up to 2%.