AT516453B1 - Metallic strips and their manufacturing processes - Google Patents

Abstract

The invention relates to a metallic strip which except Fe additionally 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 contains and a method of producing such strips with the steps - Providing a metallic strip material of predetermined thickness, width and length, - Heating up to a preheating temperature between 90 ° C and 150 ° C, - then uniform heating from the preheating temperature to a temperature between 5 ° C and 60 ° C below a predetermined target temperature within a time between 2 h - 4 h, the target temperature between 450 ° C and 700 ° C. - subsequent uniform heating to the target temperature within a period of 0.1 h - 1 h, - holding the target temperature for a period of 0.5 h - 2.5 h ("holding temperature") - cooling to an afterglow temperature between 200 ° C and 400 ° C within a time between 0.5 h - 2.5 h, - subsequent Abküh from the afterglow temperature to room temperature.

Description

Description: The invention relates to heat-treated metallic belts, in particular endless belts, and their production processes.

In this connection, US 4,420,347 discloses a method for producing an austenitic stainless steel sheet or strip. The material has 0.01-0.10% C; 0.45.0% Mn; 0.001-0.030% S; 5.0-10.0% Ni; 0.05-2.5% Cu; 0.01-0.6% Ti; 0.01-0.7% Nb; 0.2-1.3% Si; 0.003-0.045% P; 16.0-19.0% Cr; 0.05-2.4% Mo; 0.008-0.2% N and 0.01-0.3% AI.

Metallic belts are used for example for band presses or band saws. They comprise a metal sheet or a plurality of metal sheets, which may or may not be welded together. In the event that endless belts are present, which is a preferred form of use, the belts are cross-welded at their ends so that they form an endless belt. In the event that wide tapes are required, two or more tapes are often welded together at their longitudinal edges so that they form a wide tape.

In a belt press, here a double belt press, an upper and lower endless belt are moved at the same speed, with the endless belts running essentially parallel or at a small angle to one another along a working space. A small angle to each other may be necessary to compact the material to be pressed, but also due to a temperature-related change in volume.

In the work area, a pressing process takes place, the two belts being pressed together and transmitting this pressure to a workpiece passed between them during its movement.

Disadvantage of these devices is that the conventional belts have only a limited life, especially when heat acts on the belts during the pressing process, and must be replaced after a certain time.

The object of the present invention was to overcome the disadvantages of the prior art and to provide metallic strips and a production method for them, by means of which a user is able to achieve a long operating time.

This object is achieved by metallic strips and a manufacturing method according to the claims.

[0009] Weight% is indicated below with the% sign.

The metallic strips according to the invention contain, apart from Fe, which forms the residual mass, and unavoidable impurities [0011] 0.01% -0.2% C, [0012] 12% - 18% Cr, [0013] 4% - 8 % Ni [0014] 0% - 3.5% Cu [0015] 0% - 0.5% Ti [0016] 0% - 1.8% Si and [0017] 0% - 2% Mn.

The hardness [HV 10] of the heat-treated tape is between 400 and 600, preferably less than 500, and / or the tensile strength of the heat-treated tape is between 1300 N / mm ² and 1700 N / mm ² , in particular between 1450 N / mm ² and 1600 N / mm ² , and / or the yield strength 0.2% of the heat-treated strip is between 1300 N / mm ² and 1700 N / mm ² , in particular between 1400 N / mm ² and 1550 N / mm ² , and / or the bending fatigue strength of the heat-treated strip is between 600 N / mm ² and 800 N / mm ² , in particular / 6

AT516 453 B1 2018-02-15 Austrian

Patent office between 630 N / mm ² and 720 N / mm ² .

The tapes optionally contain at least 0.03% C.

Optionally, the bands contain 14% -17.5% Cr, [0021] Optionally, the bands contain 4% - 7.5% Ni, particularly preferably between 4% and 5% or between 6.5% and 7.5 %.

The tapes optionally contain 0% Cu or between 0.5% and 0.9% Cu or between 3% and 3.5% Cu.

The strips optionally contain 0% Ti or between 0.3 and 0.5% Ti, [0024] The strips optionally contain 0% Si or between 0.6% and 0.8% Si.

The tapes optionally contain 0.6% -1.4% Mn, preferably at most 1% Mn.

The hardness [HV 10] of the base material (before a heat treatment) is preferably between 300 and 500, in particular less than 400. The hardness is specified here and below according to Vickers.

The tensile strength (Rm) of the base material (before heat treatment) is preferably between 1000 N / mm ² and 1450 N / mm ² , in particular between 1050 N / mm ² and 1200 N / mm ² .

The yield strength 0.2% (Rp-0.2) of the base material (before heat treatment) is preferably between 900 N / mm ² and 1400 N / mm ² , in particular between 950 N / mm ² and 1100 N / mm ^2nd

The alternating bending strength of the base material (before a heat treatment) is preferably between 400 N / mm ² and 600 N / mm ² , in particular between 450 N / mm ² and 550 N / mm ² .

The tensile strength (Rm) of the transverse weld seam of the base material (before heat treatment) is preferably between 800 N / mm ² and 1200 N / mm ² , in particular between 900 N / mm ² and 1100 N / mm ² .

[0031] The manufacturing method of such metallic strips according to the invention comprises the steps:

- Providing a metallic strip material according to the preceding statements with a predetermined thickness, width and length, [0033] - optional: connecting at least two metallic strip materials on the longitudinal edges to form a wider strip material by means of welding (longitudinal welding), [0034] - heating up until a preheating temperature between 90 ° C and 150 ° C is reached, then uniform heating from the preheating temperature to a temperature between 5 ° C and 60 ° C, in particular a temperature between 20 ° C and 40 ° C, below one predetermined target temperature within a time between 2 h - 4 h, the target temperature being between 450 ° C and 700 ° C, [0036] - subsequent uniform heating to the target temperature within a time of 0.1 h -1 h, [0037] - Maintaining the target temperature for a period of 0.5 h - 2.5 h ("holding temperature"), - cooling to an afterglow temperature between 200 ° C and 400 ° C inside half a time between 0.5 h - 2.5 h, [0039] - subsequent cooling from the afterglow temperature to room temperature, [0040] - optional: joining the ends of the heat-treated strip material to form an endless strip by means of welding (“transverse welding”).

The preheating temperature is preferably between 100 ° C. and 140 ° C., in particular between 2/6

AT516 453 B1 2018-02-15 Austrian

Patent Office see 110 ° C and 130 ° C, with a temperature of 120 ° C (+/- 2 ° C) being particularly preferred.

The time in which this happens does not necessarily have to be determined, but it has proven to be advantageous if the heating-up time is between 0.2 h and 1 h.

The heating from the preheating temperature to a temperature below a predetermined target temperature is preferably carried out within 2.5 h - 4 h, in particular within 3 h (+/- 10 min).

Preferably, the heating to the target temperature takes place within a time of 0.5 h (+ / 5 min).

The target temperature is preferably maintained within a time between 1 h - 2 h, in particular 1.5 h (+/- 10 min).

The afterglow temperature is preferably between 250 ° C and 350 ° C, in particular 300 ° C (+/- 10 ° C).

Cooling to an afterglow temperature is preferably carried out within a time between 1 h - 2 h, in particular 1.5 h (+/- 10 min).

The target temperature depends on the strip material used and is preferably between 450 ° C and 600 ° C. In a preferred embodiment, the target temperature is on the descending branch of the heat treatment curve, ie in the range in which the function of the strength of the heat-treated strip material has a negative gradient as a function of the holding temperature.

The heat treatment curve shows the function of the strength of the heat-treated strip material (Y axis) as a function of the holding temperature (X axis). At a low holding temperature, this curve rises with increasing temperature, reaches a maximum and falls again with increasing temperatures (negative gradient).

Preferably, the holding temperature is chosen so that it is higher than the temperature of the maximum of the curve, or so that it is selected so that the function there has a negative derivative with respect to the temperature.

This has the advantage that the finished strip, if it experiences high temperatures in use, becomes softer and thus more ductile. This minimizes the likelihood of failure due to brittleness.

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

Preferably, the tensile strength of the heat-treated strip compared to the base material has increased between 350 N / mm ² and 500 N / mm ² , in particular between 380 N / mm ² and 450 N / mm ² .

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

Preferably, the fatigue strength of the heat-treated strip compared to the base material has increased between 100 N / mm ² and 300 N / mm ² , in particular between 180 N / mm ² and 220 N / mm ² .

The tensile strength of the cross weld seam of the heat-treated strip is preferably between 1000 N / mm ² and 1300 N / mm ² , in particular between 1180 N / mm ² and 1250 N / mm ² .

Preferably, the tensile strength of the cross weld seam of the heat-treated strip compared to the cross weld seam in the base material has increased between 20 N / mm ² and 150 N / mm ² , in particular between 30 N / mm ² and 110 N / mm ² .

The tensile strength of the longitudinal weld seam of the heat-treated strip is preferably between 1200 N / mm ² and 1700 N / mm ² , in particular between 1310 N / mm ² and 1550 N / mm ² .

3.6

AT516 453 B1 2018-02-15 Austrian Patent Office [0058] The hardness, tensile strength, yield strength and ability to change bends of the base material

The presence of the heat-treated material alone can be determined simply by determining the chemical composition using the specialist literature or by subsequently producing the

Base material can be determined without heat treatment.

The heat treatment of the strips is preferably carried out in an oven. The strip is preferably wound into a coil during the heat treatment. While the roll is being wound up, an additional metal foil, for example a copper foil, can be rolled up together with the strip material. This has the advantage that the layers of a roll of the strip material do not scratch each other.

According to a preferred embodiment, the strips have a length between 20 m and 190 m, preferably between 40 m and 170 m. In the case of endless belts, this means the length of one revolution over the entire belt. This is an advantageous belt length for wooden and conveyor belts.

In the event that the finished strips should be in the form of endless strips, the heat treatment is carried out in a preferred embodiment before welding to form the endless strip.

In the event that two or more strips are to be longitudinally welded to form a wide strip, in a preferred embodiment the heat treatment is preferably carried out after the welding. According to a further preferred embodiment, the heat treatment takes place before the welding.

Examples of preferred embodiments of the tapes according to the invention are shown below.

Example 1 A metal strip material consists of max. 0.09 C, 15% Cr, 7% Ni, 0.7% Cu, 0.4% Ti and balance Fe. Its tensile strength is 1150 N / mm ² and its hardness [HV 10] 360.

After the heat treatment by the inventive method with a holding temperature of 540 ° C - 570 ° C, its tensile strength is 1550 N / mm ² , and its hardness [HV 10] 480.

Example 2 A metallic strip material consists of 0.03 C, 14.5% Cr, 4.5% Ni, 3.3% Cu and the rest Fe. Its tensile strength is 1050 N / mm ² and its hardness [HV 10] 330.

After the heat treatment according to the inventive method with a holding temperature of 470 ° C - 520 ° C, its tensile strength is 1450 N / mm ² , and its hardness [HV 10] 460.

In the examples it can clearly be seen that the heat treatment increases the tensile strength and the hardness of the materials. This increase is caused by the elimination of the respective precipitation-hardening element from the thermodynamically released state. The separated elements form phases that hinder the displacements and thereby increase the hardness and strength.

In Examples 1 and 2, an element is usually removed from the crystal composite during the heat treatment without leaving the strip material (precipitation-hardening element). The respective material is thus still chemically present in the material, but is no longer part of the basic structure. The materials listed in Examples 1 and 2 are both martensitic materials. In Example 1, Ti is the precipitation hardening alloy element, in Example 2 Cu is the precipitation hardening alloy element.

The exemplary embodiments describe possible design variants, it being noted at this point that the invention is not restricted to the specially illustrated design variants, but rather also various combinations of the individual design variants

AT516 453 B1 2018-02-15 Austrian patent office are possible among each other and this possibility of variation due to the teaching of technical action through objective invention in the ability of this technical

Area of professional activity.

Furthermore, individual features or combinations of features from the different exemplary embodiments shown and described can also represent independent, inventive or inventive solutions.

The object on which the independent inventive solutions are based can be found in the description.

All information on ranges of values in the present description should be understood to include any and all subranges thereof, e.g. the indication 0% to 1% is to be understood in such a way that all sub-areas are included, starting from the lower limit 0% (not included) and the upper limit 1%, i.e. all sub-areas start with a lower limit of 0% or larger and end with an upper limit of 1% or less, e.g. 0% to 0.7%, or 0.1% to 1%, or 0.5% to 0.9%.

Above all, the individual designs can form the subject of independent solutions according to the invention.

5.6

AT516 453 B1 2018-02-15 Austrian

Patent Office

Claims (8)

claims 1. Metallic strip, which is heat-treated, characterized in that, in addition to Fe, which forms the residual mass, and unavoidable impurities, it is additionally 0.01% - 0.2% C, 12% - 18% Cr, 4% - 8% Ni , 0% - 3.5% Cu, 0% - 0.5% Ti, 0% - 1.8% Si and 0% - 2% Mn (% signs correspond to% by weight) and its hardness [HV 10 ] between 400 and 600 and / or its tensile strength between 1300 N / mm ² and 1700 N / mm ² and / or its yield strength 0.2% between 1300 N / mm ² and 1700 N / mm ² and / or its flexural fatigue strength between 600 N / mm ² and 800 N / mm ² . 2. Metallic strip according to claim 1, characterized in that the strip has a length between 20 m and 190 m, preferably between 40 m and 170 m. 3. Metallic strip according to one of the preceding claims, characterized in that it has a cross weld and / or a longitudinal weld, preferably the tensile strength of the cross weld between 1000 N / mm ² and 1300 N / mm ² , in particular between 1180 N / mm ² and 1250 N / mm ² and / or the tensile strength of the longitudinal weld seam is between 1200 N / mm ² and 1700 N / mm ² . 4. Method of manufacturing metallic strips according to one of the preceding claims, comprising the steps: Provision of a metallic strip material of predetermined thickness, width and length, - heating up to a preheating temperature between 90 ° C and 150 ° C, - subsequent uniform heating from the preheating temperature to a temperature between 5 ° C and 60 ° C below a predetermined target temperature within a time between 2 h - 4 h, the target temperature being between 450 ° C and 700 ° C, - subsequent uniform heating to the target temperature within a period of 0.1 h - 1 h, - maintaining the target temperature for a period of 0.5 h - 2.5 h ("holding temperature"), Cooling to an afterglow temperature between 200 ° C and 400 ° C within a time between 0.5 h - 2.5 h, - then cooling from the afterglow temperature to room temperature. 5. The method according to claim 4, characterized in that at least two metallic Strip materials are joined together at the longitudinal edges to form a wider strip material by means of welding (longitudinal welding), in particular before the heat treatment and / or that the ends of the heat-treated strip material are connected to form a strip by means of welding (“transverse welding”), in particular after the heat treatment. 6. The method according to any one of claims 4 or 5, characterized in that the Heating from the preheat temperature to a temperature between 20 ° C and 40 ° C below the target temperature. 7. The method according to any one of claims 4 to 6, characterized in that the target temperature is between 450 ° C and 600 ° C and / or that the target temperature is in the range in which the function of the strength of the heat-treated strip material depending on the holding temperature has a negative gradient. 8. The method according to any one of claims 4 to 7, characterized in that the heat treatment of the strips is carried out in an oven, wherein the strip is preferably wound into a coil during the heat treatment.