GB2158096A

GB2158096A - Steel alloy for bicycle frame tubing

Info

Publication number: GB2158096A
Application number: GB08509787A
Authority: GB
Inventors: Stefan Klatzer
Original assignee: Benteler Deustchland GmbH
Current assignee: Benteler Deustchland GmbH
Priority date: 1984-04-26
Filing date: 1985-04-17
Publication date: 1985-11-06
Also published as: DE3415526C2; IT1181766B; DE3415526A1; JPH044389B2; JPS60234951A; GB2158096B; GB8509787D0; FR2568845A1; IT8547766A1; FR2568845B1; IT8547766A0

Abstract

A steel alloy is disclosed for use in making bicycle frame tubing with very favourable static and dynamic loading properties for the intended use. The steel comprises from 0.14 to 0.18% carbon, from 0.15 to 0.30% silicon, from 1.6 to 1.8% manganese, from 1.9 to 2.1% chromium, from 0.45 to 0.60% molybdenum, at least 0.015% aluminium and iron. The alloy is prepared in known manner and first annealed at from 900 to 930 DEG C, then air-quenched, then tempered at temperatures between 500 and 650 DEG C. A material of this kind is particularly resistant to fatigue stress and therefore has a long life.

Description

SPECIFICATION Steel alloy for making bicycle frame tubing This invention relates to the use of a steel alloy for making bicycle frame tubing.

Sports bicycles in particular are subject to very heavy stressing, more particularly in the case of sports such as cross-country racing or bicycle ball.

Bicycle frames of light metal are found to be unsuitable for sports of this kind, as are as simple steels, Constructions are therefore known where in high-carbon quenched and tempered steels are used for bicycle frame tubing.

Steels of this kind must be hardened in oil or water.

A disadvantage of this approach is that the tubing becomes greatly distorted as early as the manufacturing stage and has to be realigned. The realignment in turn means that the known bicycle frame tubing has relatively substantial residual stress.

The conventional quenched and tempered steels are relatively difficult to weld satisfactory because of their relatively high carbon content.

When conventional steel bicycle frame tubing is welded or soldered together, microscopic cracks may arise and lead to rapid fracture of the bicycle frame when the same is subject to heavy stressing.

The yield point of the material used for known bicycle frame tubing is somewhere between 400 and 500 N/mm2 and materials of this kind have a iinear expansion of approximately from 8 to 10%.

Consequently, the working stress of a bicycle frame made of tubing of this kind is fairly low and, because of the disadvantages mentioned, such frames have a fairly short working life.

Relatively thick-walled tubes have previously been used in an endeavour to obviate these disadvantages, but increase the weight of the frame, a particular disadvantage when bicycles of this kind are required to be used for sporting activities.

It is an object of this invention to provide a steel alloy for use in making bicycle frame tubing, which alloy has very advantageous static and dynamic stress features for the intended use.

Accordingly, the invention provides bicycle frame tubing made from a steel alloy which comprises from 0.14 to 0.18% carbon, from 0.15 to 0.30% silicon, from 1.6 to 1.8% manganese, from 1.9 to 2,1% chromium, from 0.45 to 0.60% molybdenum, at least 0.015% aluminium and iron.

The invention further provides a bicycle frame made from bicycle tubing in accordance with the invention.

In another aspect, the invention provides a method of making a bicycle frame tubing, including forming the tubing from a steel alloy comprising from 0.14 to 0.18% carbon, from 0.15 to 0.30% silicon, from 1.6 to 1.18% manganese, from 1.9 to 2.1% chromium, from 0.45 to 0.60% molybdenum, at least 0.015% aluminium and iron, annealing at from 900 to 930 C, air-quenching and then tempering at tempertures between 500 and 650 C.

The advantages provided by the invention are mainly that a steel alloy embodying the invention can withstand severe static and dynamic stresses.

The yield point of material in accordance with the invention is around 600 to 800 N/mm2 with a linear expansion of around 12 to 20%.

A material of this kind is more particularly well able to withstand fatigue stress and so bicycle frame tubing made therefrom has a long life.

These properties of the material make it possible for bicycle frame tubing to be relatively thinwalled, so that a bicycle frame having correspondingly good properties is light in weight.

The conventional strengthening of bicycle frame tubing at joints becomes unnecessary thanks to the properties of the steel alloy used in accordance with the invention, so that not only is material saved but also a very elaborate and expensive manufacturing operation, previously necessary to thicken the tubing at joints, becomes unnecessary; previously the thickening operation involved mechanical deformation of the tubing by means of a conical mandrel or the like. Since a steel alloy in accordance with the invention is air-quenched, distortion of tubing constructed from the alloy is zero or negligibly small, so that realigning treatment is virtually unnecessary. Welding and soldering tubing of this kind does not lead to potential weakness at joints since the material in accordance with the invention can be welded and soldered without impairment of its properties.

The comparatively low carbon content of the steel alloy is advantageous, more particularly as regards welding of the material.

In short, therefore, use of a steel alloy in accordance with the invention to make bicycle frame tubing improves mechanical properties, reduces costs and, another important consideration, helps to reduce weight.

Consequently, a bicycle with a frame constructed from tubing of this kind is, as compared with conventional constructions, able to cope with heavier mechanical stressing, has a longer life, can be produced more cheaply and, because of its reduced weight, is more easily and readily controllable by an athlete.

1. Bicycle frame tubing made from a steel alloy which comprises from 0.14 to 0.18% carbon, from 0.15 to 0.30% silicon, from 1.6 to 1.8% manganese, from 1.9 to 2.1% chromium, from 0.45 to 0.60% molybdenum, at least 0.015% aluminium and iron.

2. Bicycle frame tubing substantially as hereinbefore described.

3. A bicycle frame made from tubing according to Claim 1 or 2.

4. A method of making a bicycle frame tubing, including forming the tubing from a steel alloy comprising 0.14 to 0.18% carbon, from 0.15 to 0.30% silicon, from 1.6 to 1.18% manganese, from 1.9 to 2.1% chromium, from 0.45 to 0.60% molybdenum, at least 0.015% aluminium and iron, annealing at from 900 to 930 C, air-quenching and

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **. SPECIFICATION Steel alloy for making bicycle frame tubing This invention relates to the use of a steel alloy for making bicycle frame tubing. Sports bicycles in particular are subject to very heavy stressing, more particularly in the case of sports such as cross-country racing or bicycle ball. Bicycle frames of light metal are found to be unsuitable for sports of this kind, as are as simple steels, Constructions are therefore known where in high-carbon quenched and tempered steels are used for bicycle frame tubing. Steels of this kind must be hardened in oil or water. A disadvantage of this approach is that the tubing becomes greatly distorted as early as the manufacturing stage and has to be realigned. The realignment in turn means that the known bicycle frame tubing has relatively substantial residual stress. The conventional quenched and tempered steels are relatively difficult to weld satisfactory because of their relatively high carbon content. When conventional steel bicycle frame tubing is welded or soldered together, microscopic cracks may arise and lead to rapid fracture of the bicycle frame when the same is subject to heavy stressing. The yield point of the material used for known bicycle frame tubing is somewhere between 400 and 500 N/mm2 and materials of this kind have a iinear expansion of approximately from 8 to 10%. Consequently, the working stress of a bicycle frame made of tubing of this kind is fairly low and, because of the disadvantages mentioned, such frames have a fairly short working life. Relatively thick-walled tubes have previously been used in an endeavour to obviate these disadvantages, but increase the weight of the frame, a particular disadvantage when bicycles of this kind are required to be used for sporting activities. It is an object of this invention to provide a steel alloy for use in making bicycle frame tubing, which alloy has very advantageous static and dynamic stress features for the intended use. Accordingly, the invention provides bicycle frame tubing made from a steel alloy which comprises from 0.14 to 0.18% carbon, from 0.15 to 0.30% silicon, from 1.6 to 1.8% manganese, from 1.9 to 2,1% chromium, from 0.45 to 0.60% molybdenum, at least 0.015% aluminium and iron. The invention further provides a bicycle frame made from bicycle tubing in accordance with the invention. In another aspect, the invention provides a method of making a bicycle frame tubing, including forming the tubing from a steel alloy comprising from 0.14 to 0.18% carbon, from 0.15 to 0.30% silicon, from 1.6 to 1.18% manganese, from 1.9 to 2.1% chromium, from 0.45 to 0.60% molybdenum, at least 0.015% aluminium and iron, annealing at from 900 to 930 C, air-quenching and then tempering at tempertures between 500 and 650 C. The advantages provided by the invention are mainly that a steel alloy embodying the invention can withstand severe static and dynamic stresses. The yield point of material in accordance with the invention is around 600 to 800 N/mm2 with a linear expansion of around 12 to 20%. A material of this kind is more particularly well able to withstand fatigue stress and so bicycle frame tubing made therefrom has a long life. These properties of the material make it possible for bicycle frame tubing to be relatively thinwalled, so that a bicycle frame having correspondingly good properties is light in weight. The conventional strengthening of bicycle frame tubing at joints becomes unnecessary thanks to the properties of the steel alloy used in accordance with the invention, so that not only is material saved but also a very elaborate and expensive manufacturing operation, previously necessary to thicken the tubing at joints, becomes unnecessary; previously the thickening operation involved mechanical deformation of the tubing by means of a conical mandrel or the like. Since a steel alloy in accordance with the invention is air-quenched, distortion of tubing constructed from the alloy is zero or negligibly small, so that realigning treatment is virtually unnecessary. Welding and soldering tubing of this kind does not lead to potential weakness at joints since the material in accordance with the invention can be welded and soldered without impairment of its properties. The comparatively low carbon content of the steel alloy is advantageous, more particularly as regards welding of the material. In short, therefore, use of a steel alloy in accordance with the invention to make bicycle frame tubing improves mechanical properties, reduces costs and, another important consideration, helps to reduce weight. Consequently, a bicycle with a frame constructed from tubing of this kind is, as compared with conventional constructions, able to cope with heavier mechanical stressing, has a longer life, can be produced more cheaply and, because of its reduced weight, is more easily and readily controllable by an athlete. CLAIMS

2. Bicycle frame tubing substantially as hereinbefore described.

3. A bicycle frame made from tubing according to Claim 1 or 2.

4. A method of making a bicycle frame tubing, including forming the tubing from a steel alloy comprising 0.14 to 0.18% carbon, from 0.15 to 0.30% silicon, from 1.6 to 1.18% manganese, from 1.9 to 2.1% chromium, from 0.45 to 0.60% molybdenum, at least 0.015% aluminium and iron, annealing at from 900 to 930 C, air-quenching and then tempering at temperatures between 500 and 6509C.

5. A method of making bicycle frame tubing substantially as hereinbefore desribed.

6. Any novel feature or combination of features described herein.