SK288714B6 - Metal strips and method of their production - Google Patents

Abstract

A method for production of metal band is described, wherein the metal band in addition to Fe contains 0,01 % – 0,2 % of C, 12 % – 17 % of Cr, 4 % – 8 % of Ni, 0 % – 3,5 % of Cu, 0 % – 0,5 % of Ti, 0 % – 1,8 % of Si and 0 % – 2 % of Mn. The metal band is produced by the following steps: a) preparation of metal band material having in advance given thickness, width and length; b) heating up to the pre-annealing temperature between 90°and 150 °C; c) subsequent regular heating from the pre-annealing temperature up to the temperature, that is by a value between 5 °C and 60 °C lower than in advance defined target temperature during 2 hours – 4 hours, the target temperature is between 450 °C and 700 °C; d) subsequent regular heating to the target temperature during 0.1 to 1 hour; e) remaining at the target temperature during 0.5 to 2.5 hours; f) cooling to the post-annealing temperature between 200 °C and 400 °C during 0.5 hour to 2.5 hours and g) subsequent cooling from post-annealing temperature to the room temperature.

Description

Technical field

The invention relates to a method for producing metal strips, preferably endless strips.

BACKGROUND OF THE INVENTION

Metal bands are used, for example, for band presses or band saws. They consist of a sheet or several sheets which may be welded together or welded together. When they are endless belts, which is one preferred embodiment, these strips are transversely welded at their ends to form an endless belt. When wide strips are required, often two or more strips are welded together at their longitudinal edges to form a wide stripe.

In the case of a belt press, in this case a double belt press, the upper and lower endless belts move at the same speed, and in the working space these endless belts are guided substantially parallel or at a slight angle relative to each other. molded material, but also due to the change in volume depending on the temperature.

A pressing process takes place in the work space, the two belts being pressed against each other and transmitting this pressure on them between them during movement.

The disadvantage of these devices is that conventional belts have only a limited lifetime, especially when high temperatures are applied to the belt processing and must be replaced after some time.

The object of the present invention was to overcome the disadvantages of the prior art and to provide metal strips and a method for their production, by means of which the user would be able to obtain a longer service life in operation.

SUMMARY OF THE INVENTION

This object will be achieved by the production of metal strips according to the aforementioned patent claims.

The method for producing metal strips according to the invention comprises the following steps:

- preparing a metal strip material according to the foregoing interpretation with a predetermined thickness, width and length,

- optional: joining at least two metal strip materials along their longitudinal edges into a wider strip material by welding (also "longitudinal welding"),

- heating until reaching a pre-annealing temperature between 90 ° C and 150 ° C,

- subsequent uniform heating from the preheating temperature to a temperature which is between 5 ° C and 60 ° C, preferably between 20 ° C and 40 ° C lower than the predetermined target temperature for between 2 h - 4 h, whereby the target temperature is between 450 ° C and 700 ° C,

- subsequent uniform heating to the target temperature over 0,1 h - 1 h,

- endurance at the target temperature for 0,5 h - 2,5 h (hereinafter also referred to as "endurance temperature"),

- cooling to a blistering temperature between 200 ° C and 400 ° C within 0,5 h - 2,5 h,

- subsequent cooling from the annealing temperature to room temperature,

- optionally: joining the ends of the heat-treated sheet material to form an endless belt by welding (also "cross-welding").

The annealing temperature is preferably between 100 ° C and 140 ° C, preferably between 110 ° C and 130 ° C, with a temperature of 120 ° C (+/- 2 ° C) being particularly preferred. The time over which this occurs does not necessarily have to be determined, but has shown to be advantageous if the heating time is between 0.2 h and 1 h.

Heating from the preheating temperature to a temperature lower than the predetermined target temperature is preferably performed within 2.5 h - 4 h, particularly preferably within 3 h (+/- 10 min).

Suitably, heating to the target temperature occurs within 0.5 h (+/- 5 min).

Stability at the target temperature is preferably carried out between 1 h - 2 h, particularly preferably 1.5 h (+/- 10 min).

The annealing temperature s and preferably ranges between 250 ° C and 350 ° C, particularly preferably around 300 ° C (+/- 10 ° C).

The cooling to the annealing temperature is preferably carried out within 1 h - 2 h, particularly preferably 1.5 h (+/- 10 min).

The target temperature depends on the sheet material used and is preferably between 450 ° C and 600 ° C. In one preferred embodiment, the target temperature lies on the " descending branch " of the heat treatment curve, that is, in the area in which the strength function of the heat treated web material has a negative gradient depending on the holding temperature.

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The heat treatment curve shows the function of the heat-treated strip material (y-axis) as a function of the holding temperature (x-axis). This curve increases at low hold temperatures with increasing temperature, then reaches a maximum and decreases again as the temperature rises (negative gradient).

The holding temperature is preferably chosen to be higher than the maximum temperature of said curve or the temperature of said curve. such that it is chosen such that at that point said function has a negative derivative with respect to temperature.

This has the advantage that if the finished web is to be subjected to high temperatures in operation, it should soften and thus obtain greater ductility. This minimizes the likelihood of failure due to brittleness.

In the following, the percentages are percentages by weight.

The metal strips of the present invention contain in addition to Fe, which constitutes the remainder of the weight, and the necessary impurities

0.03% - 0.2% C,% -17% Cr,% - 6% Ni,% - 3.5% Cu,% - 0.5% Ti,% - 0.8% Si and 0% - 1% Qty.

The hardness [HV 10] of the base material (prior to the heat treatment) is preferably between 300 and 400. The hardness of the satin and referred to below is according to Vickers.

The hardness of the heat treated strip with and preferably ranges between 400 and 500.

The hardness [HV 10] of the heat treated strip preferably increased by between 100 and 200 compared to the base material.

The tensile strength (R m) of the base material (prior to heat treatment) is preferably between 1000 N / m ² and 1,450 N / m ² , preferably between 1,050 N / m ² and 1,200 N / m ² .

The tensile strength of the heat treated strip is preferably between 1,300 N / m 2 and 1,700 N / mm ² , particularly preferably between 1,450 N / mm ² and 1,600 N / m 2.

The tensile strength of the heat treated strip preferably increased by between 350 N / m 2 and 500 N / mm ² , particularly preferably between 380 N / mm ² and 450 N / mm ² , compared to the base material.

The yield strength of 0.2% (Rp - 0.2) of the base material (prior to heat treatment) is preferably between 900 N / mm ² and 1,400 N / mm ² , preferably between 950 N / mm ² and 1,100 N / m 2. .

The yield strength of 0.2% of the heat treated strip is preferably between 1,300 N / m 2 and 1,700 N / mm ² , particularly preferably between 1,400 N / m 2 and 1,550 N / m 2.

The yield strength of 0.2% of the heat treated strip has preferably increased by between 350 N / mm ² and 500 N / mm ² , particularly preferably between 380 N / mm ² and 430 N / m ² compared to the base material.

The AC bending fatigue strength of the base material (prior to heat treatment) is preferably between 400 N / mm ² and 600 N / m 2, preferably between 450 N / mm ² and 550 N / mm ² .

The AC bending fatigue strength of the heat treated strip is preferably between 600 N / mm ² and 800 N / m 2, particularly preferably between 630 N / mm ² and 720 N / m 2.

The AC bending fatigue strength of the heat treated strip has preferably increased by between 100 N / mm ² and 300 N / mm ² , particularly preferably between 180 N / mm ² and 220 N / mm ² compared to the base material.

The tensile strength (Rm) of the transverse weld of the base material (prior to heat treatment) is preferably between 800 N / mm ² and 1200 N / m 2, preferably between 900 N / mm ² and 1 100 N / m 2.

The transverse tensile strength of the heat treated strip is preferably between 1000 N / m ² and 1300 N / mm ² , particularly preferably between 1 180 N / mm ² and 1250 N / mm ² .

The tensile strength of the transverse weld of the heat treated strip preferably increased by between 20 N / mm ² and 150 N / m 2, especially between 30 N / mm ² and 110 N / mm ² , relative to the transverse weld in the base material.

The tensile strength of the longitudinal weld of the heat treated strip is preferably between 1,200 N / m 2 and 1,700 N / m 2, particularly preferably between 1,310 N / m 2 and 1,550 N / mm ² .

If only a heat-treated material is available, the hardness, tensile strength, yield point and fatigue limit at alternating bending stress of the base material can be determined simply by determining the chemical composition based on the literature or by additional production of the base material without heat treatment.

The metal strips of the present invention contain in addition to Fe, which constitutes the remainder of the weight, and the necessary impurities

0.01% - 0.2% C,% - 17% Cr,% - 8% Ni,

S K 288714 B6% - 3.5% Cu,% - 0.5% Ti,% -1.8% Si and 0% - 2% Mn.

The bands optionally contain 0.6% - 1.4% Mn and 0.15% - 0.35% Si.

The hardness [HV 10] of the base material (prior to heat treatment) is preferably between 300 and 500. The hardness of the satin and referred to below is according to Vickers.

The hardness [HV 10] of the heat treated strip with and preferably ranges between 400 and 600.

The hardness [HV 10] of the heat treated strip preferably increased by between 100 and 200 compared to the base material.

The tensile strength (Rm) of the base material (prior to heat treatment) is preferably between 1,000 N / mm ² and 1,450 N / mm ² , preferably between 1,200 N / mm ² and 1,420 N / mm ² .

The tensile strength of the heat treated strip is preferably between 350 N / mm ² and 500 N / mm ² , particularly preferably between 380 N / mm ² and 450 N / mm ² .

The yield strength of 0.2% (Rp - 0.2) of the base material (prior to heat treatment) is preferably between 900 N / mm ² and 1400 N / mm ² , preferably between 950 N / mm ² and 1350 N / mm ² .

The yield strength of 0.2% of the heat treated strip has preferably increased by between 350 N / mm ² and 500 N / mm ² , particularly preferably between 380 N / mm ² and 430 N / mm ² compared to the base material.

The AC bending fatigue strength of the base material (prior to heat treatment) is preferably between 400 N / mm ² and 600 N / mm ² , preferably between 450 N / mm ² and 550 N / mm ² .

The AC bending fatigue strength of the heat treated strip has preferably increased by between 100 N / mm ² and 300 N / mm ² , particularly preferably between 180 N / mm ² and 220 N / mm ² compared to the base material.

The tensile strength (Rm) of the transverse weld of the base material (prior to heat treatment) is preferably between 900 N / mm ² and 1200 N / mm ² , preferably between 950 N / mm ² and 1150 N / mm ² .

The tensile strength of the transverse weld of the heat treated strip preferably increased by between 20 N / mm ² and 150 N / mm ² , more preferably between 30 N / mm ² and 110 N / mm ² , compared to the transverse weld in the base material.

If only a heat-treated material is available, the hardness, tensile strength, yield point and fatigue limit at alternating bending stress of the base material can be determined simply by determining the chemical composition based on the literature or by additional production of the base material without heat treatment.

The heat treatment of the strips is preferably carried out in an oven. In this case, the strip is preferably wound into a coil (also coil) during the heat treatment. During the winding of the coil, another metal foil, for example a copper foil, may be wound together with the web material. This has the advantage that the coil layers of the sheet material do not scratch each other.

According to one preferred embodiment, the strips have a length of between 20 m and 190 m, preferably between 40 m and 170 m. This represents an advantageous length for wood belts and conveyor belts.

In the event that the belt is to be available in the form of endless belts, the heat treatment is carried out in one preferred embodiment before welding into the endless belt.

If two or more strips are to be longitudinally welded into one wide strip, the heat treatment is carried out in one preferred embodiment, preferably after welding. According to a further preferred embodiment, the heat treatment is carried out before welding

Hereinafter, preferred embodiments of the inventive belts will be presented.

An embodiment of the invention

Example 1

The metal strip material consists of max. 0.09% C, 15% Cr, 7% Ni, 0.7% Cu, 0.4% Ti and the remainder Fe. Its tensile strength is 1 150 N / mm ² and its hardness [HV 10] 360.

After heat treatment according to the method of the present invention with a holding temperature of 540 ° C - 570 ° C, it has a tensile strength of 1,550 N / mm ² and a hardness [HV 10] of 480.

Example 2

The metal strip material consists of 0.03% C, 14.5% Cr, 4.5% Ni, 3.3% Cu and the remainder Fe. Its tensile strength is 1,050 N / mm ² and its hardness [HV 10] 330.

After heat treatment according to the method of the present invention with a holding temperature of 470 ° C - 520 ° C, it has a tensile strength of 1,450 N / mm ² and a hardness [HV 10] of 460.

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The examples clearly show that heat treatment increases the tensile strength and hardness of the materials. This increase is due to the exclusion of the respective dispersion curing element from the thermodynamically relaxed state. The excluded elements form phases which prevent displacements and thereby increase hardness and strength.

In Examples 1 and 2, in the heat treatment, usually one element is excreted from the crystal structure without leaving the sheet material (dispersion curing element). Thus, the substance is still chemically present in the material, but is no longer part of the underlying microstructure. Both materials of Examples 1 and 2 are martensitic materials. In Example 1, the dispersion curing alloy element is Ti, in Example 2 the dispersion curing alloy element is Cu.

These exemplary embodiments describe possible embodiments, and it has been noted at this point that the present invention is not limited to the specific embodiments described, but that, in addition, different combinations of the individual embodiments are possible and this variation possibility results from the technical knowledge of according to the present invention within the skills of a person skilled in the art.

Furthermore, the individual features or combinations of features of the various embodiments illustrated and described may also be separate inventive solutions or solutions of the invention.

The role of separate inventive solutions may be inferred from this description.

All data relating to the ranges of values in this specification is to be understood in the sense that these data simultaneously include any and all sub-ranges, e.g. an indication of 0% to 1% is to be understood as including all sub-ranges, based on the lower 0% (which is not included) and the 1% upper limit, at the same time. j. all sub-ranges start with a lower limit of 0% or higher and end with an upper limit of 1% or lower, for example 0% to 0.7%, or 0.1% to 1%, or 0.5% to 0.9%.

In particular, the individual embodiments may form the subject of separate solutions according to the invention.

Claims (9)

PATENT CLAIMS A method of manufacturing metal strips, comprising the steps of: providing a metal strip material of a predetermined thickness, width and length; heating to a pre-annealing temperature between 90 ° C and 150 ° C; subsequently uniform heating from the pre-heating temperature to a temperature between 5 ° C and 60 ° C below the predetermined target temperature for between 2 h - 4 h, the target temperature being between 450 ° C and 700 ° C; subsequent uniform heating to the target temperature for a time between 0.1 h -1 h; holding at target temperature for 0.5 h - 2.5 h; cooling to a blending temperature between 200 ° C and 400 ° C for a period between 0.5 h - 2.5 h and subsequent cooling from the blending temperature to room temperature. Method according to claim 1, characterized in that the at least two metal strip materials are joined together by welding along the longitudinal edges into a wider strip material, preferably before the heat treatment, and / or that the ends of the heat treated strip material are joined to the strip by welding , preferably after heat treatment. Method according to any one of the preceding claims, characterized in that it is heated to a temperature between 20 ° C and 40 ° C lower than the target temperature when heated from the preheating temperature. Method according to any one of the preceding claims, characterized in that the target temperature is between 450 ° C and 600 ° C and / or that the target temperature lies on the downward branch of the heat treatment curve, in an area in which the heat treated strength function the strip material has a negative gradient depending on the holding temperature. Method according to one of the preceding claims, characterized in that the heat treatment of the strips takes place in an oven, the strip being wound into a roll during the heat treatment. Method according to any one of the preceding claims, characterized in that a metal strip material is used which, in addition to Fe, constituting the rest of the weight and the necessary impurities, additionally contains 0.01% - 0.2% C, 12% - 17% Cr, 4% - 8% Ni, 0% - 3.5% Cu, 0% - 0.5% Ti, 0% - 1.8% Si and 0% - 2% Mn. Method according to claim 6, characterized in that a metal strip material is used which has a length between 20 m and 190 m, preferably between 40 m and 170 m. Method according to either of Claims 6 or 7, characterized in that a metal strip material having a hardness [HV 10] of between 300 and 500 and / or a tensile strength (Rm) of between 1000 N / m 2 is used and 1450 N / mm ² , and / or the yield strength 0.2% (Rp - 0.2) between 900 N / mm ² and 1400 N / mm ² , and / or the fatigue limit at alternating bending stresses between 400 N / mm ² and 600 N / mm ² , and / or tensile strength R m of the transverse weld between 800 N / mm ² and 1 200 N / mm ² , and / or tensile strength of the longitudinal weld between 1200 N / mm ² and 1 700 N / mm ² . Method according to one of Claims 6 to 8, characterized in that, in the heat-treated strip, the hardness [HV 10] has been increased by between 100 and 200 and / or the tensile strength by between 350 N / mm ² and 500 N / mm ² , and / or the yield strength of 0.2% by between 350 N / mm ² and 500 N / mm ² , and / or the fatigue limit at alternating bending stress by between 100 N / mm ² and 300 N / mm ² , and / or the transverse weld tensile strength of between 20 N / mm ² and 150 N / mm ² .