SI24902A - Metal strips and procedure of their manufacture - Google Patents

Abstract

The invention relates to a metal strip which in addition to Fe 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, and is made by the steps: - providing metal strip material of a predetermined thickness, width and length, - heating to achieve a pre-heating temperature of 90 degrees Celsius and 150 degrees Celsius, - then steady heating from the pre-heating temperature to a temperature between 5 degrees Celsius and 60 degrees Celsius under a predetermined target temperature for a period of between 2 h and 4 h, the target temperature being between 450 degrees Celsius and 700 degrees Celsius , - then steady heating to the target temperature for a time between 0.1 h - 1 h, - holding the target temperature for a time of 0.5 h - 2.5 h ("holding temperature"), - cooling to a fire temperature between 200 degrees Celsius and 400 degrees Celsius for a time between 0.5 h -2.5 h, - then cooling from the fire temperature to room temperature.

Description

METAL BANDS AND THEIR MANUFACTURING PROCEDURE

The invention relates to metal strips, in particular endless strips and the process of their manufacture.

Metal bands are used e.g. for band presses and band saws. They comprise a metal sheet or several metal sheets which, if necessary, are welded to one another. are welded to one another. In the case of the existence of an endless strip, which is the preferred form of use, the straps at their ends are welded transversely to form an endless strip. Where wide strips are required, two or more strips are often welded to one another along their longitudinal edges to form a wide stripe.

In the case of a belt press, here a two-line press, the upper and lower endless bands move at the same speed, with the endless bands running substantially parallel or at a smaller angle along the workspace. A smaller mutual angle may be required to solidify the material to be compressed, but also on the basis of temperature-dependent volume changes.

A compression process is carried out in the workspace whereby the straps are pressed together and this pressure is transferred to the workpiece between them during their movement.

The disadvantage of such a device is that conventional tapes have only a limited lifespan, especially if the heat is applied during the compression process and need to be replaced after a certain time.

It is an object of the present invention to address the disadvantages of the prior art and to provide metal strips and a manufacturing process for them that will enable the user to achieve a longer shelf life.

This task is solved with metal strips and a manufacturing process according to claims.

The process of manufacturing metal strips according to the invention comprises the steps of:

- the provision of metal strip material of a predetermined thickness, width and length,

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

- heating to achieve a pre-firing temperature between 90 ° C and 150 ° C,

- then uniform heating from pre-ignition temperature to a temperature between 5 ° C and 60 ° C, in particular to a temperature between 20 ° C and 40 ° C, below a predetermined target temperature between 2 h and 4 h, the target temperature being between 450 ° C and 700 ° C,

- then uniform heating to the target temperature over 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 a fire temperature of between 200 ° C and 400 ° C for a time between 0,5 h and 2,5 h,

- then cooling from fire temperature to room temperature,

- optional: joining the ends of the heat-treated strip material into an endless strip by welding (cross welding).

Preferably, the pre-ignition temperature is between 100 ° C and 140 ° C, in particular between 110 ° C and 130 ° C, with a temperature of 120 ° C (+/- 2 ° C) being particularly preferred. The time at which this occurs is not necessarily determined, but it is useful if the warm-up time is between 0.2 h and 1 h.

Preferably, heating from pre-ignition temperature to a temperature below a predetermined target temperature is carried out for 2.5 h - 4 h, especially 3 h (+/- 10 min).

Preferably, heating to the target temperature is carried out for 0.5 h (+/- 5 min).

• ·

Preferably, the target temperature is maintained for 1 h - 2 h, especially 1.5 h (+/- 10 min).

Preferably, the fire temperature is between 250 ° C and 350 ° C, especially at 300 ° C (+ / 10 ° C).

Preferably, the cooling to the fire temperature is carried out during 1 h - 2 h, in particular

1.5 h (+/- 10 min).

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

The heat treatment curve shows the strength function of the heat treated tape material (y-axis) as a function of the holding temperature (x-axis). This curve rises at a low holding temperature with increasing temperature, reaches a maximum, and drops again at further rising temperatures (negative gradient).

Preferably, the holding temperature is selected so that it is higher than the maximum curve temperature or. thus, it is chosen such that the function here has a negative drainage according to temperature.

This has the advantage of becoming a finished band, in the case of high temperatures, being softer and therefore more ductile. The probability of error due to the occurrence of fragility is thus reduced to the lowest value.

The following are the% weight%.

The metal strips of the invention are made by the process of the invention and, in addition to Fe, which forms the residual mass, and inevitable impurities contain 0.03% - 0.2% C,

14% - 18% Cr,

4% - 6% Ni,

0% - 3.5% Cu,

0% - 0.5% Ti,

0% - 0.8% Si in

0% - 1% Mn.

Preferably, the hardness [HV 10] of the base material (prior to heat treatment) is between 300 and 400. The hardness is indicated here and hereafter by Vickers.

Preferably, the hardness [HV 10] of the heat treated strip is between 400 and 500.

Preferably, the hardness [HV 10] of the heat treated strip is increased by a value between 100 and 200 relative to the base material.

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

Preferably, the tensile strength of the heat treated strip is between 1300 N / mm ² and 1700 N / mm ² , in particular between 1450 N / mm ² and 1600 N / mm ² .

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

Preferably, the stretching limit of 0.2% (Rp-0.2) of the base material (before heat treatment) is between 900 N / mm ² and 1400 N / mm ² , in particular between 950 N / mm ² and 1100 N / mm ² .

Preferably, the stretching limit of 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 .

Preferably, the stretching limit of 0.2% of the heat-treated strip is increased by a value between 350 N / mm and 500 N / mm relative to the base material, in particular between 380 N / mm and 430 N / mm ² .

Preferably, the flexural strength of the base material (before heat treatment) is between 400 N / mm ² and 600 N / mm ² , in particular between 450 N / mm ² and 550 N / mm ² .

Preferably, the durable flexural strength of the heat treated strip is between 600 N / mm ² and 800 N / mm ² , in particular between 630 N / mm ² and 720 N / mm ² .

Preferably, the durable flexural strength of the heat treated strip relative to the base material is increased by a value between 100 N / mm and 300 N / mm, in particular between 180 N / mm and 220 N / mm ² .

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

Preferably, the tensile strength of the cross weld of the heat treated strip is 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-welded heat treated strip relative to the transverse weld in the base material is increased by a value between 20 N / mm and 150 N / mm, in particular between 30 N / mm ² and 110 N / mm ² .

Preferably, the tensile strength of the longitudinal weld of the heat treated strip is between 1200

N / mm ² and 1700 N / mm ² , in particular between 1310 N / mm ² and 1550 N / mm ² .

The hardness, tensile strength, tensile strength, and permanent flexural strength of the base material in the existence of the heat-treated material itself can be easily determined after the chemical composition has been established by professional literature or by the subsequent fabrication of the base material without heat treatment.

The metal strips of the invention are manufactured by the process of the invention and, in addition to Fe, which forms the residual mass, and inevitable impurities contain 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.

Optionally, the strips contain 0.6% - 1.4% Mn and 0.15% - 0.35% Si.

Preferably, the hardness [HV 10] of the base material (before heat treatment) is between 300 and 500. The hardness is given here and hereafter by Vickers.

Preferably, the hardness [HV 10] of the heat treated strip is between 400 and 600.

Preferably, the hardness [HV 10] of the heat treated strip is increased by a value between 100 and 200 relative to the base material.

Preferably, the tensile strength (Rra) of the base material (before heat treatment) is between 1000 N / mm ² and 1450 N / mm ² , in particular between 1200 N / mm ² and 1420 N / mm ² .

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

Preferably, the stretching limit of 0.2% (Rp-0.2) of the base material (before heat treatment) is between 900 N / mm ² and 1400 N / mm ² , in particular between 950 N / mm ² and 1350 N / mm ² .

Preferably, the stretch limit is 0.2% of the heat treated tape relative to the base

2 2 increases the material by a value between 350 N / mm and 500 N / mm, in particular between 380 N / mm and 430 N / mm ² .

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

Preferably, the durable flexural strength of the heat treated strip relative to the base material is increased by between 100 N / mm ² and 300 N / mm ² , in particular between 180 N / mm ² and 220 N / mm ² .

Preferably, the tensile strength (Rm) of the transverse weld of the base material (before heat treatment) is between 900 N / mm ² and 1200 N / mm ² , in particular between 950 N / mm ² and 1150 N / mm ² .

Preferably, the tensile strength of the thermal weld of the heat treated strip relative to the transverse weld in the base material is increased by a value between 20 N / mm ² and 150 N / mm ² , in particular between 30 N / mm ² and 110 N / mm ² .

The hardness, tensile strength, tensile strength, and permanent flexural strength of the base material in the existence of the heat-treated material itself can be easily determined after the chemical composition has been established by professional literature or by the subsequent fabrication of the base material without heat treatment.

The heat treatment of the strips is preferably carried out in an oven. The tape is preferably wound on a reel (Coil) during the heat treatment process. During the winding of the reel, an additional metal foil, e.g. copper foil. This has the advantage that the layers of the strip material are not scattered.

According to a preferred embodiment, the straps have a length between 20 m and 190 m, preferably between 40 m and 170 m. In the case of endless bands, this means the length of the circumvention of the entire strip. This represents the preferred band lengths for forestry and conveyor belts.

In the case that the finished strips are in the form of endless strips, the heat treatment in the preferred embodiment is carried out before welding into the infinite strips.

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

The following are examples of preferred embodiments of the tapes of the invention.

Example 1

The metal strip material consists of not more than 0.09% C, 15% Cr, 7% Ni, 0.7% Cu, 0.4% Ti and the rest of Fe. Its tensile strength is 1150 N / mm ² and its hardness [HV 10] 360.

After heat treatment according to the process of the invention with a holding temperature of 540 ° C to 570 ° C, its tensile strength is 1550 N / mm ² , and its hardness [HV 10] is 480.

Example 2

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

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

In the cases it is clearly shown that the heat treatment increases the tensile strength and the hardness of the material. This increase is caused by the separation of the respective separating hardening element from the thermodynamically released state. The eliminated elements form phases that prevent movement and thus increase the hardness and strength.

In cases 1 and 2, as a rule, one element is generally removed from the crystal structure during heat treatment without leaving the strip material (separating hardening element). Thus, the individual material is still chemically present in the material, but is no longer part of the basic structure. The materials derived from Examples 1 and 2 are martensite materials. In example 1, Ti is a curing legume element, in case 2, Cu is a curing alloy element.

Embodiments describe possible embodiments, and it should be noted that the invention is not limited to specially presented embodiments, but many different combinations of individual embodiments are possible, and these modifications are possible based on the technical operation of the present invention and knowledge expert in the technical field.

Further, individual characteristics may also be depicted ah combinations of features from the various embodiments shown and described for independent, inventive solutions and / or inventions. the solutions according to the invention.

The task underlying the independent solutions of the invention may be taken from the description.

The entire data for the value areas in the present description should be understood to cover any and all partial areas, e.g. the indication of 0% to 1% should be understood to mean that the entire partial areas are between the lower limit of 0% (not contained) and the upper limit of 1%, ie. the entire partial areas start from the lower limit 0% ah higher and end at the upper limit 1% ah lower, e.g. 0% to 0.7% ah 0.1% to 1% ah 0.5% to 0.9%.

In particular, the individual embodiments can form an object with independent solutions according to the invention.

Claims (9)

Patent claims A method of manufacturing metal strips, comprising the steps of: - the provision of metal strip material of a predetermined thickness, width and length, - heating to achieve a pre-firing temperature between 90 ° C and 150 ° C, - then uniform heating from the pre-ignition temperature to a temperature between 5 ° C and 60 ° C, below a predetermined target temperature for a time between 2 h and 4 h, with a target temperature between 450 ° C and 700 ° C, - then uniform heating to the target temperature over a period of 0,1 h - 1 h, - maintaining the target temperature, ie holding temperature for a period of 0.5 h 2.5 h, - cooling to a fire temperature of between 200 ° C and 400 ° C for a time between 0,5 h and 2,5 h, - then cooling from fire temperature to room temperature. A method according to claim 1, characterized in that at least two metal strip materials along the longitudinal edges are interconnected into a wider strip material by means of longitudinal welding, especially before heat treatment and / or to connect the ends of the heat treated strip material to endless tape by cross welding, especially after heat treatment. Method according to any one of the preceding claims, characterized in that, when heated from a pre-ignition temperature to a temperature between 20 ° C and 40 ° C, it is heated below the target temperature. Method according to any one of the preceding claims, characterized in that the target temperature lies between 450 ° C and 600 ° C and / or that the target temperature lies on the falling branch of the heat treatment curve, in the region in which the heat-treated strength function strip material, depending on the holding temperature, negative gradient. Method according to any one of the preceding claims, characterized in that the heat treatment of the strips is carried out in a furnace, the strip being preferably wound on a reel during the heat treatment. Metal strip manufactured by the method according to any one of the preceding claims, characterized in that it additionally contains 0.01% - 0.2% C, 12% - 17% in addition to Fe forming the residual mass and unavoidable impurities Cr, 4% - 8% Ni, 0% - 3.5% Cu, 0% - 0.5% Ti, 0% - 1.8% Si and 0% - 2% Mn. Metal strip according to claim 6, characterized in that the strip has a length between 20 m and 190 m, preferably between 40 m and 170 m. Metal strip according to claim 6 or 7, characterized in that the base material has a hardness of HV 10 between 300 and 500 and / or a tensile strength Rm of between 1000 N / mm ² and 1450 N / mm ² and / or a boundary prior to heat treatment. elongation 0,2% Rp-02 between 900 N / mm ² and 1400 N / mm ² and / or permanent flexural strength between 400 N / mm ² and 600 N / mm ² and / or the tensile strength Rm of the cross weld between 800 N / mm ² and 1200 N / mm ² and / or the tensile strength of the longitudinal weld between 1200 N / mm ² and 1700 N / mm ² . Metal strip according to any one of claims 6 to 8, characterized in that the hardness of the HV 10 heat-treated endless strip is increased by a value between 100 and 200 and / or a tensile strength by a value between 350 N / mm relative to the base material. ² and 500 N / mm ² and / or a tensile limit of 0.2% for a value between 350 N / mm ² and 500 N / mm ² and / or permanent flexural strength for a value between 100 N / mm ² and 300 N / mm ² and / or the tensile strength of the transverse weld for a value between 20 N / mm ² and 150 N / mm ² .