Hot-rolled steel and method for producing the same

Abstract

Hot-rolled steel containing the following elements, namely, 5% ≤ nickel ≤ 16%, 0.5% ≤ aluminum ≤ 3%, 0.1% ≤ titanium ≤ 1%, 4% ≤ chromium ≤ 15%, 0.0001% ≤ carbon ≤ 0.03%, 0.002% ≤ phosphorus ≤ 0.02%, 0% ≤ sulfur ≤ 0.005%, 0% ≤ nitrogen ≤ 0.01%, 0% ≤ cobalt ≤ 7%, 0% ≤ molybdenum ≤ 6%, 0% ≤ niobium ≤ 0.1%, 0% ≤ vanadium ≤ 0.3%, 0% ≤ copper ≤ 0.5%, 0% ≤ manganese ≤ 2%, 0% ≤ silicon ≤ 1%, 0% ≤ boron ≤ 0.001%, 0% ≤ oxygen ≤ 0.004%, 0% ≤ magnesium ≤ 0.0010%, and having a composition in which the remaining composition is composed of iron and inevitable impurities generated by processing. The microstructure of the steel sheet contains, in area fraction, at least 95% martensite, 1% - 5% reverse-transformed austenite, and an intermetallic compound of aluminum, titanium, and nickel.

Description

Technical Field

[0001] The present invention relates to hot-rolled steel suitable for use in a corrosive environment, particularly an environment containing chlorides.

Background Art

[0002] Previous research and development in the field of high-strength and high-formability steels with corrosion resistance has led to several methods for steel, some of which are listed herein for a final understanding of the present invention.

[0003] US20100037994 claims a method of processing a workpiece of maraging steel, the method comprising receiving a workpiece of maraging steel having a composition containing 17 wt% to 19 wt% nickel, 8 wt% to 12 wt% cobalt, 3 wt% to 5 wt% molybdenum, 0.2 wt% to 1.7 wt% titanium, 0.15 wt% to 0.15 wt% aluminum, and the balance iron, and having a composition hot-mechanically processed at an austenite solutionizing temperature, and directly aging the workpiece of maraging steel at an aging temperature without intervening heat treatment between the hot-mechanical processing and the direct aging to form precipitates in the microstructure of the workpiece of maraging steel, the hot-mechanical processing and the direct aging including providing a workpiece of maraging steel having an average ASTM grain size of 10. However, US20100037994 does not guarantee corrosion resistance and only claims a method of economically processing maraging steel.

[0004] EP2840160 provides a maraging steel having excellent fatigue properties, which, expressed in mass%, contains C≦0.015%, Ni: 12.0 to 20.0%, Mo: 3.0 to 6.0%, Co: 5.0 to 13.0%, Al: 0.01 to 0.3%, Ti: 0.2 to 2.0%, O≦0.0020%, N≦0.0020%, and Zr: 0.001 to 0.02%, with the balance being Fe and inevitable impurities. EP2840160 provides the required appropriate strength but does not provide a steel having corrosion resistance in a chloride environment.

Prior Art Documents

Patent Document

[0005]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0006] The object of the present invention is to solve these problems by providing a hot-rolled steel having the following simultaneously. - Tensile strength of 1100 MPa or more, preferably exceeding 1200 MPa, - Hardness of 545 Hv or less, preferably 535 Hv or less, - Corrosion-resistant steel considered to have corrosion resistance when the thickness loss due to corrosion is less than 0.07 mm / year, preferably less than 0.06 mm / year

[0007] In a preferred embodiment, the steel according to the present invention may also exhibit a yield strength of 850 MPa or more.

[0008] Preferably, such steel can also have good weldability and coatability, as well as good compatibility with forming, particularly rolling.

[0009] Another object of the present invention is also to make available a method for manufacturing these plates that is stable against shifts in manufacturing parameters while being suitable for conventional industrial applications.

[0010] The hot-rolled steel sheet of the present invention may be coated as necessary to further improve its corrosion resistance.

Means for Solving the Problems

[0011] The above object and other advantages of the present invention will become more apparent by describing preferred embodiments of the present invention in detail.

[0012] The chemical composition of the hot-rolled martensitic steel contains the following elements, and each element is indicated by its presence expressed in weight percent.

[0013] Nickel is present in the steel at 5% to 16%. Nickel is an essential element in the steel of the present invention in order to form an intermetallic compound with aluminum and titanium during heating before tempering and impart strength to the steel. Also, nickel is effective in suppressing the formation of the ferrite phase and increasing the proportion of the martensite phase, thereby improving corrosion resistance. Nickel also plays an extremely important role in the formation of reverse transformation austenite during tempering and limits the hardness of the steel to 550 Hv. However, less than 5% nickel cannot impart strength due to a decrease in the formation of intermetallic compounds, while if nickel is present in excess of 16%, it forms more than 10% reverse transformation austenite, which is also harmful to the tensile strength of the steel. The preferred content of nickel in the present invention is 6% to 15%, and more preferably can be maintained at 6.5% to 14%.

[0014] Aluminum is an essential element constituting 0.5% to 3% of the steel of the present invention. Aluminum increases the strength of the steel of the present invention by forming an intermetallic compound with nickel and titanium during tempering. Aluminum is an essential element for imparting corrosion resistance to the steel of the present invention. Further, the steel of the present invention is cleaned by adding aluminum to the molten steel to remove oxygen present in the molten steel and prevent oxygen from forming a gas phase. The preferred limit of aluminum is 0.8% to 2.5%, more preferably 0.9% to 2%.

[0015] The titanium content of the steel of the present invention is 0.1% to 1%. Titanium forms an intermetallic compound and imparts strength to the steel. If titanium is less than 0.1%, the required effect is not achieved. The preferred content for the present invention is 0.1% to 0.9%, more preferably 0.2% to 0.8%.

[0016] Chromium is an essential element that constitutes 4% - 15% of the steel of the present invention. Chromium is an important element for ensuring corrosion resistance, i.e., stress corrosion cracking resistance, in a harsh corrosion environment. Furthermore, chromium helps to effectively transform the steel microstructure into martensite during cooling after annealing. To obtain these effects, at least 4% of Cr must be contained. However, when the content exceeds 15%, ferrite is likely to be formed in the metal structure of the steel, and it becomes difficult to obtain a martensite structure by quenching. Therefore, the preferred chromium content is 5% - 14%, and a more preferred range is 6% - 12%.

[0017] Carbon is present in the steel in an amount of 0.0001% - 0.03%. Carbon is a residual element and is derived from processing. Impurity carbon less than 0.0001% is impossible due to process limitations, and the presence of carbon exceeding 0.03 must be avoided as it reduces the corrosion resistance of the steel.

[0018] The phosphorus component of the steel of the present invention is 0.002% - 0.02%. Phosphorus reduces spot weldability and hot workability, and in particular, reduces spot weldability and hot workability due to its tendency to segregate at grain boundaries or co-segregation. For these reasons, its content is limited to 0.02%, preferably less than 0.015%.

[0019] Sulfur is not an essential element, but may be contained as an impurity in the steel. From the perspective of the present invention, it is preferable that the sulfur content is as low as possible, but from the perspective of manufacturing cost, it is 0.005% or less. Furthermore, when more sulfur is present in the steel, it combines to form sulfides, reducing its beneficial effect on the steel of the present invention, and therefore less than 0.003% is preferred.

[0020] Nitrogen is limited to 0.01% to avoid aging of the material. Nitrogen forms nitrides that impart strength to the steel of the present invention through precipitation strengthening with vanadium and niobium. However, whenever the presence of nitrogen exceeds 0.01%, there is a possibility of forming a large amount of aluminum nitride, which is harmful to the present invention. Therefore, the preferred upper limit of nitrogen is 0.005%.

[0021] Cobalt is an optional element of the steel of the present invention and is present in an amount of 0% to 7%. The purpose of adding cobalt is to help impart ductility to the steel. In addition, cobalt also serves to form intermetallic compounds of nickel by reducing the proportion of nickel and forming a solid solution. However, when cobalt is present in an amount greater than 7%, it forms excessive reverse-transformed austenite, which is harmful to the strength of the steel. The preferred content of cobalt for the present invention can be maintained at 0 to 6%, more preferably 0 to 5%.

[0022] Molybdenum is an optional element that constitutes 0% to 6% of the steel of the present invention. Molybdenum increases the strength of the steel of the present invention by forming intermetallic compounds with nickel and titanium during heating for tempering. Molybdenum helps to achieve the corrosion resistance characteristics of the steel of the present invention. However, the addition of molybdenum excessively increases the cost of adding alloying elements. For economic reasons, its content is limited to 6%. The preferred limit of molybdenum is 0 to 5%, more preferably 0 to 4%.

[0023] Niobium is an optional element of the present invention. The niobium content may be present in the steel of the present invention in an amount of 0% to 0.1% and is added to the steel of the present invention to form carbides or carbonitrides so as to impart strength to the steel of the present invention through precipitation strengthening.

[0024] Vanadium is an optional element that constitutes 0% to 0.3% of the steel of the present invention. Vanadium is effective in increasing the strength of steel by forming carbides, nitrides or carbonitrides, and the upper limit is 0.3% for economic reasons. These carbides, nitrides or carbonitrides are formed during the second and third stages of cooling. The preferred limit of vanadium is 0% to 0.2%.

[0025] By adding copper as an optional element in an amount of 0% to 0.5%, the strength of the steel can be increased and the corrosion resistance can be improved. In order to obtain such an effect, at least 0.01% of copper is required. However, if the content exceeds 0.5%, the surface morphology may deteriorate.

[0026] The manganese content of the steel of the present invention is 0% to 2%. This element is gammagenous. Manganese provides solid solution strengthening, suppresses the ferrite transformation temperature, reduces the ferrite transformation rate, and thus helps the formation of martensite. However, when the manganese content exceeds 2%, adverse effects such as delaying the transformation from austenite to martensite during cooling after annealing occur. A manganese content exceeding 2% may segregate excessively in the steel during solidification, impairing the homogeneity inside the material and causing surface cracks during the hot working process. The preferred limit for the presence of manganese is 0% to 1%.

[0027] The silicon content of the steel of the present invention is 0% to 1%. Silicon is an element that contributes to the strength improvement by solid solution strengthening. Silicon is a component that can delay the precipitation of carbides during cooling after annealing, and thus silicon promotes the formation of martensite. However, silicon is also a ferrite former and raises the Ac3 transformation point, which pushes the annealing temperature into a higher temperature range. This is the reason why the silicon content is maintained at a maximum of 1%. A silicon content exceeding 1% can also enhance embrittlement. The preferred limit for the presence of silicon is 0% to 0.5%, more preferably 0% to 0.4%.

[0028] Other elements such as boron, oxygen or magnesium can be added individually or in combination in the following weight ratios, i.e., boron ≤ 0.001%, oxygen ≤ 0.004%, magnesium ≤ 0.0010%. Up to the maximum content levels shown, these elements enable the refinement of the crystal grains during solidification.

[0029] The remainder of the steel composition consists of iron and inevitable impurities resulting from processing.

[0030] The microstructure of the steel includes the following.

[0031] Martensite constitutes at least 95% of the microstructure in area fraction and is the matrix microstructure of the steel of the present invention. The martensite of the present invention can include both fresh martensite and tempered martensite. However, fresh martensite is an optional minor component preferably limited in the steel in an amount of 0% to 4%, preferably 0% to 2%, and even more preferably equal to 0%. Fresh martensite can occur during cooling after tempering. Tempered martensite is formed from martensite formed during the second stage of cooling after annealing, particularly after Ms temperature, more specifically after Ms - 10°C to 20°C. Such martensite is then tempered while being held at a tempering temperature Temper of 450°C to 680°C. The martensite of the present invention imparts ductility and strength to such steel. Preferably, the content of martensite is 96% to 99%, more preferably 96% to 98%.

[0032] Reverse transformation austenite is present in the steel of the present invention in an area fraction of 1% to 5%. Reverse transformation austenite is formed by the transformation of martensite to austenite during tempering of the steel and is simultaneously enriched and stabilized with nickel. The reverse transformation austenite of the steel of the present invention imparts both hardness and corrosion resistance. Preferably, the content of reverse transformation austenite is 1% to 4%, more preferably 1% to 3%.

[0033] Intermetallic compounds of nickel, titanium and aluminum are present in the steel of the present invention. These intermetallic compounds are formed during heating up to the tempering temperature and during the tempering process. The intermetallic compounds formed are both intergranular and intragranular intermetallic compounds. The intergranular intermetallic compounds of the present invention are present in both martensite and reverse-transformed austenite. The shape of these intermetallic compounds of the present invention can be cylindrical or spherical. The intermetallic compounds of the steel of the present invention are formed as Ni3Ti, Ni3Al or Ni3(Ti,Al) intermetallic compounds. The intermetallic compounds of the steel of the present invention impart strength and particularly corrosion resistance to the steel of the present invention in a chloride environment. However, Ti6Si7Ni 16 If G-phase intermetallic compounds such as Mn6Si7Ni16 are present in the steel, they increase the hardness of the steel beyond 550 Hv and are also harmful to the corrosion resistance characteristics of the steel of the present invention. The G-phase also embrittles the steel. Therefore, the steel of the present invention is maintained to be free of G-phase intermetallic compounds.

[0034] In addition to the above microstructure, the microstructure of the hot-rolled steel sheet does not contain microstructure components such as ferrite, bainite, pearlite and cementite, although they may be found in trace amounts. Some trace iron intermetallic compounds such as iron-aluminum and iron-nickel may be present, but their presence does not significantly affect the properties of the steel during use.

[0035] The steel of the present invention can be formed into seamless tube-shaped products or steel sheets, and further into structural parts or operating parts used in industries in severe environments containing chlorides or any other industries in corrosive environments.

[0036] In a preferred embodiment for the illustration of the present invention, the steel sheet according to the present invention can be manufactured by the following method. The preferred method is to provide a semi-finished casting of steel having the chemical composition according to the present invention. The casting can be in the form of an ingot, billet, bar, or can be carried out continuously in the form of a thin slab or thin strip, i.e., with a thickness ranging from about 220 mm for a slab to several tens of millimeters for a thin strip.

[0037] For example, the slab having the above chemical composition is manufactured by continuous casting, and the slab is optionally subjected to direct soft reduction during the continuous casting process to avoid central segregation. The slab provided by the continuous casting process can be used directly at a high temperature after continuous casting, or can be first cooled to room temperature and then reheated for hot rolling.

[0038] The temperature of the slab to be subjected to hot rolling should preferably be at least 1150°C and must be less than 1300°C. If the temperature of the slab is less than 1150°C, an excessive load will be applied to the rolling mill. Therefore, it is preferred that the temperature of the slab is high enough to complete hot rolling within the 100% austenite range. Reheating at a temperature exceeding 1275°C causes a loss of productivity and is also industrially expensive. Therefore, the preferred reheating temperature is 1150°C to 1275°C.

[0039] Thereafter, the reheated slab is hot rolled. The hot rolling finishing temperature of the present invention is 800°C to 975°C, preferably 800°C to 950°C.

[0040] Next, the hot rolled steel strip thus obtained is cooled from the hot rolling finishing temperature to a cooling stop temperature CS1 which is 10°C to Ms. The preferred CS1 temperature range is 15°C to Ms - 20°C. The cooling rate CR1 from the hot rolling finishing temperature to CS1 is preferably 1°C / second to 100°C / second. In a preferred embodiment, CR1 for cooling after the hot rolling finishing temperature is 1°C / second to 80°C / second, more preferably 1°C / second to 50°C / second.

[0041] Thereafter, the hot-rolled steel strip is heated to an annealing temperature TA which is from Ae3 to Ae3 + 350°C. The hot-rolled steel strip is held at the annealing temperature for a duration of 30 minutes or more. In a preferred embodiment, TA is from Ae3 + 20°C to Ae3 + 350°C, more preferably from Ae3 + 40°C to Ae3 + 300°C. The heating starts from CS1 at a heating rate HR1 of at least 1°C / second until it reaches the TA temperature. In a preferred embodiment, the heating rate HR1 for such heating is at least 5°C / second, more preferably at least 10°C / second or more.

[0042] Then, after being held at the annealing temperature, the hot-rolled steel strip is cooled preferably at a cooling rate CR2 of 1°C / second to 100°C / second. In a preferred embodiment, the cooling rate CR2 for the cooling after being held at the annealing temperature is 1°C / second to 80°C / second, more preferably 1°C / second to 50°C / second. The hot-rolled steel strip is cooled to a temperature range CS2 which is from 10°C to Ms after annealing, and preferably, the CS2 temperature is from 15°C to Ms - 20°C. During this cooling process, fresh martensite is formed, and the cooling rate CS2 must exceed 1°C / second to ensure that the hot-rolled strip is essentially completely martensite.

[0043] Next, the annealed hot-rolled steel strip is heated to the tempering temperature Ttemper at a heating rate HR2 of 0.1 °C / second to 100 °C / second, preferably 0.1 °C / second to 50 °C / second, and even more preferably 0.1 °C / second to 30 °C / second. During this heating and tempering, intermetallic compounds of nickel, titanium, and aluminum are formed. The intermetallic compounds formed during this heating and tempering are both intragranular and intergranular, and are formed as Ni3Ti, Ni3Al, or Ni3(Ti,Al) intermetallic compounds. The tempering temperature Ttemper is 450 °C to 700 °C, and the steel is tempered for a duration of 30 minutes to 72 hours. In a preferred embodiment, Ttemper is 490 °C to 690 °C, more preferably 500 °C to 680 °C. During the tempering hold, the fresh martensite converted to tempered martensite not only due to the presence of nickel, but also some amount of fresh martensite underwent reverse transformation to form reverse transformation austenite. The reverse transformation austenite formed during tempering, within the tempering temperature range of the present invention, some of the intermetallic compounds formed during heating dissolve, enriching the austenite with nickel, and this nickel-enriched reverse transformation austenite is stable at room temperature, so it is enriched with nickel.

[0044] Thereafter, the hot-rolled steel strip is cooled to room temperature to obtain hot-rolled steel.

Examples

[0045] The following tests, examples, illustrative examples, and tables presented in this specification are essentially non-limiting and are to be considered for illustrative purposes only and show the advantageous features of the present invention.

[0046] Steel plates made of steels with different compositions are summarized in Table 1, with each element shown by its presence in weight percent and the balance being iron and other process impurities, and the steel is manufactured according to the process parameters specified in Table 2 respectively. Thereafter, the microstructures of the steels obtained during the trials are summarized in Table 3, and the results of evaluating the obtained properties are summarized in Table 4.

[0047]

Table 1

[0048] For all steel samples, Ms is calculated according to the following formula. Ms = 764.2 - 302.6C - 30.6Mn - 16.6Ni - 8.9Cr + 2.4Mo - 11.3Cu + 8.58Co + 7.4W - 14.5Si In the formula, the element content is expressed in weight percent.

[0049] On the other hand, Ae3 (°C) is calculated according to the following formula. Ae3 = 955 - 350C - 25Mn + 51Si + 106Nb + 100Ti + 68Al - 11Cr - 33Ni - 16Cu + 67Mo In the formula, the element content is expressed in weight percent.

[0050] Table 2 Table 2 summarizes the process parameters implemented for the steel in Table 1.

[0051]

Table 2

[0052] Table 3 Table 3 illustrates the results of tests conducted according to standards on different microscopes such as a scanning electron microscope for determining the microstructure of both the steel of the present invention and the reference steel.

[0053] The surface fraction of the phases in the microstructure is determined by the following method. The sample is cut from the steel plate, polished, and etched with a reagent known per se to reveal the microstructure. The determination of reverse transformation austenite is performed by XRD, and for martensite, a dilatometry test was conducted according to the publication of S.M.C. Van Bohemen and J. Sietsma, Metallurgical and materials transactions, Vol. 40A, May 2009 - 1059.

[0054] The results are defined in this specification.

[0055]

Table 3

[0056] Table 4 illustrates the mechanical properties of both the steel of the present invention and the reference steel. To determine the tensile strength and hardness, tests are carried out on type A25 specimens in accordance with the NBN EN ISO 6892-1 standard.

[0057] The corrosion resistance test is carried out in accordance with the accelerated chloride corrosion resistance test, where the thickness of the steel specimen is measured in millimeters (mm), and then such a steel specimen is immersed in a chloride solution having a chloride concentration of 1000 ppm at a temperature of 20 °C for one week. Then, the steel specimen is taken out after one week. Thereafter, the thickness of the steel specimen is measured again. The difference in the thickness of the steel specimen indicates the loss of steel due to corrosion, expressed in mm / year. Therefore, the thinner the steel becomes, the more easily it corrodes, and the less the thinning, the more corrosion resistant it is.

[0058] Summarize the results of various mechanical tests conducted in accordance with the standards.

[0059]

Table 4

Claims

1. A hot-rolled steel comprising the following elements expressed in weight percent, namely, 5% ≤ nickel ≤ 16% 0.5% ≤ aluminum ≤ 3% 0.1% ≤ titanium ≤ 1% 4% ≤ chromium ≤ 15% 0.0001% ≤ carbon ≤ 0.03% 0.002% ≤ phosphorus ≤ 0.02% 0% ≤ sulfur ≤ 0.005% 0% ≤ nitrogen ≤ 0.01% and including one or more of the following optional elements, namely, 0% ≤ cobalt ≤ 7% 0% ≤ molybdenum ≤ 6% 0% ≤ niobium ≤ 0.1% 0% ≤ vanadium ≤ 0.3% 0% ≤ copper ≤ 0.5% 0% ≤ manganese ≤ 2% 0% ≤ silicon ≤ 1% 0% ≤ boron ≤ 0.001% 0% ≤ oxygen ≤ 0.004% 0% ≤ magnesium ≤ 0.0010% wherein the remaining composition has a composition composed of iron and inevitable impurities generated during processing, and the microstructure of the steel sheet includes, in area fraction, at least 95% martensite, 1% - 5% reverse-transformed austenite, and intermetallic compounds of aluminum, titanium, and nickel, a hot-rolled steel.

2. The hot-rolled steel according to Claim 1, wherein the composition contains 6% - 15% nickel.

3. The hot-rolled steel according to Claim 1 or 2, wherein the composition contains 0.8% - 2.5% aluminum.

4. The hot-rolled steel according to any one of Claims 1 - 3, wherein the composition contains 5% - 14% chromium.

5. The hot-rolled steel according to any one of Claims 1 - 4, wherein the composition contains 0.1% - 0.9% titanium.

6. The intermetallic compounds of aluminum, titanium, and nickel are Ni ３ Ti, Ni ３ Al or Ni ３ The hot-rolled steel according to any one of claims 1 to 5, which is at least one or more selected from (Ti, Al).

7. The hot-rolled steel according to any one of Claims 1 - 6, wherein the reverse-transformed austenite is 1% - 4%.

8. The hot-rolled steel according to any one of Claims 1 - 7, having a tensile strength of 1100 MPa or more and a hardness of 545 Hv or less.

9. A method for manufacturing a hot-rolled steel including the following continuous steps. - A step of providing a steel composition according to any one of Claims 1 - 5, - A step of reheating the semi-finished product to a temperature of 1150°C - 1300°C, - A step of rolling the semi-finished product in the austenite range, obtaining a hot-rolled steel strip with a hot-rolling finishing temperature of 800°C - 975°C, - Then, a step of cooling the hot-rolled steel strip to a temperature CS1 that is 10°C - Ms. - Thereafter, heating the hot-rolled steel strip at a heating rate HR1 of at least 1 °C / sec to an annealing temperature TA of Ae3 to Ae3 + 350 °C, and holding the hot-rolled strip at the TA temperature for at least 30 minutes; - Next, cooling the hot-rolled steel strip at a rate of 1 °C / sec to 100 °C / sec to a temperature CS2 in a temperature range of 10 °C to Ms; - Thereafter, reheating the hot-rolled steel strip at a heating rate HR2 in the range of 0.1 °C / sec to 100 °C / sec to a tempering temperature Ttemper of 450 °C to 700 °C, and holding the hot-rolled steel strip in the tempering temperature range for 30 minutes to 72 hours; - Next, cooling the hot-rolled steel strip to room temperature to obtain hot-rolled steel.

10. The method according to claim 9, wherein the annealing temperature TA is Ae3 + 20 °C to Ae3 + 350 °C.

11. The method according to claim 9 or 10, wherein the tempering temperature Ttemper is 490 °C to 690 °C.

12. The method according to any one of claims 9 to 11, wherein the heating rate HR2 for tempering is 0.1 °C / sec to 50 °C / sec.

13. The method according to any one of claims 9 to 12, wherein the hot-rolled finishing temperature is 800 °C to 950 °C.

14. Use of the steel according to any one of claims 1 to 8 or the steel manufactured according to the method according to any one of claims 9 to 13 for the manufacture of industrial structural parts or operating parts in a harsh environment.

15. A seamless tube, pipe or part according to claim 14.

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