Steel alloys, articles of manufacture, and methods

Abstract

Steel alloys, articles of manufacture made from the steel alloys, and methods of welding weld studs to substrates are disclosed.

Description

[Technical Field]

[0001] Described herein are steel alloys and articles of manufacture made therefrom. Additionally, a method for welding a weld stud to a substrate is also described. [Background technology]

[0002] Many applications require joining elements. One such application is joining two elements by welding a fastening element, such as a weld stud, to a substrate, such as a steel plate, using a welding gun. A welding current is passed through the weld stud to liquefy the weld stud and substrate material. The weld stud is then immersed in the liquefied material before solidifying. One potential material for such fastening elements is steel with a certain amount of carbon. The amount of electrical energy used during the welding process (hereafter "welding energy") applied to a single weld stud is typically well over 10 kJ, but can be as low as less than 3 kJ in some applications.

[0003] One of the limitations of steel, especially when used in welding applications, relates to loss of strength due to embrittlement, which can be caused in some situations by carbon forming brittle regions in the steel, especially in low welding energy situations.

[0004] It would be beneficial to provide alternative designs that address some or all of the above limitations, or at least provide the public with options. Summary of the Invention [Means for solving the problem]

[0005] Throughout this specification, any reference to percent ("%") is to be understood as the proportion (weight percent) of the respective alloying element relative to the weight or mass of the total steel alloy.

[0006] According to one aspect, the constraint is: 0-0.08% carbon, 0-1% silicon, 0-2% manganese, 0 to 0.045% phosphorus, 0-0.03% sulfur, 16-20% chromium and 2.0-3.0% molybdenum, 8-14% nickel, 0-0.1% nitrogen, 0-0.7% titanium, the balance being iron and impurities, and incidental amounts of residual elements which do not adversely affect the basic and novel properties provided by the alloy; This is addressed by a steel alloy consisting essentially of:

[0007] Too high a carbon or sulfur content can result in undesirable levels of brittle phases after liquefaction of the steel, for example during welding processes, particularly during welding processes with low welding energy and / or low welding current (e.g., amperage less than 350 A). In a preferred embodiment, the steel alloy contains 0-0.03% carbon and / or 0-0.012% sulfur.

[0008] Silicon and titanium have been found to compensate for the deleterious carbon with respect to embrittlement. In a preferred embodiment, the steel alloy contains 0.5-0.75% silicon and / or 0.2-0.7% titanium. In another preferred embodiment, the amount of silicon and the amount of titanium together total at least 0.5%. In a further preferred embodiment, the amount of silicon and the amount of titanium are at least 0.5% greater than the amount of carbon. In another preferred embodiment, the ratio of the amount of titanium to the amount of carbon is greater than 6. That is, the amount of titanium is, for example, more than six times the amount of carbon to ensure the offset of the deleterious carbon. In a further preferred embodiment, the ratio of the amount of titanium to the amount of carbon is greater than 8, or greater than 10.

[0009] In another preferred embodiment, the steel alloy comprises 16-18% chromium and / or 2.0-2.5% molybdenum and / or 10-14% nickel.

[0010] In a currently preferred embodiment, manufactured articles such as fastening elements or weld studs are manufactured from the proposed steel alloys, which may be present in the bulk material of the article or may be added as elements pressed into a semi-finished product to manufacture the article or as a surface layer, e.g., a coating.

[0011] In another preferred embodiment, the article of manufacture forms a fastening element, in particular a weld stud.

[0012] According to another aspect, a method for welding a weld stud to a substrate includes providing a weld stud fabricated from a proposed steel alloy, passing a welding current through the weld stud between the weld stud and the substrate, partially liquefying the material of the weld stud and / or the substrate, solidifying the liquefied material of the weld stud and / or the substrate, and immersing the weld stud in the liquefied material of the weld stud and / or the substrate before the liquefied material solidifies. In a preferred embodiment, the amperage of the welding current is less than 350 A.

[0013] The specimens made from the above-mentioned materials showed excellent resistance to carbon-induced cracking, especially in the weld seam formed after the welding operation. Furthermore, the embedment depth of the weld stud in the substrate can be increased compared to weld studs made from common materials.

[0014] Further aspects and advantages of the steel alloy, article of manufacture, and welding method will become apparent from the following description, which is given by way of example only and which refers to the accompanying drawings. [Brief explanation of the drawings]

[0015] [Figure 1] FIG. 1 is a diagram illustrating a welding device. [Figure 2] FIG. 2 is a longitudinal cross-sectional view of a weld stud. [Figure 3] FIG. 2 is a longitudinal cross-sectional view of a weld stud. DETAILED DESCRIPTION OF THE INVENTION

[0016] FIG. 1 shows a schematic diagram of a welding apparatus 10 for welding a weld stud 20 to a substrate 30, such as structural steel. The materials of the weld stud 20 and the substrate 30 are electrically conductive. The welding apparatus 10 includes a welding gun 40 having a trigger switch 41 formed as a pushbutton switch, a welding unit 50, a first electric cable 61, a second electric cable 62 having a connection terminal 63, an electric supply cable 64 formed as, for example, a power cable, a telecommunication line 65, a gas reservoir 70 formed as a gas cylinder, a tubular gas supply line 71, and a gas hose 72. The first cable 61 serves to supply electric current to the weld stud 20 via the welding unit 50. The second cable 62 serves to electrically connect the substrate 30 to the welding unit 50 when the connection terminal 63 is clamped to the substrate 30. When the weld stud 20 comes into contact with the substrate 30, a circuit is closed, thereby allowing a welding current, for example, in the form of direct or alternating current, to be applied to the weld stud 20 by the welding unit 50. The gas supply line 71 and the gas hose 72 serve to supply inert gas from the gas reservoir 70 to the contact area between the weld stud 20 and the substrate 30 to protect the contact area from oxidation by oxygen from the surrounding area during the welding operation. To control the flow of gas to the contact area, the gas reservoir 70, the gas supply line 71, the welding unit 50, the gas hose 72 or the welding gun 40 include valves, in particular controllable valves, not shown.

[0017] The welding unit 50 has an input device 51 with an actuation element 52 and an output device 53 with a visual display element 54 and a wireless transmission unit. The input device 51 serves to input parameters of a welding method to be performed by the welding device 10 by a user of the welding device 10, such as, for example, voltage, current strength, power and duration of the welding current, position and speed of the stud, etc. The output device 53 serves to output information to the user, such as, for example, information about the parameters of the welding method, information about detected emissions of the welding method or other variables, information about the quality of the welding operation, information about measures for improving the welding operation, information about detected characteristics of the welding stud or information derived from the aforementioned variables, and / or recommendations or instructions for cleaning and / or maintaining the welding device 10, in particular the welding gun 40. A communication line 65 serves to communicate between the welding gun 40, in particular a control device of the welding gun 40 (not shown in FIG. 1 ), and the welding unit 50, in particular the control unit and / or the input device 51 and / or the output device 53. For example, this communication may effect the exchange of information regarding the parameters of the welding operation, for example to achieve or facilitate the synchronization of the welding current with the movement of the weld stud 20 .

[0018] The welding gun 40 has a housing 42 with an opening 46 from which a handle 43 having a trigger switch 41 protrudes. The welding gun 40 also has a stud holder 44, on which the weld stud 20 is held during the welding operation. For this purpose, the stud holder may include, for example, two, three, four, or more resilient arms (not shown in detail), between which the weld stud 20 is inserted and held by a clamping engagement. The welding gun 40 also has a welding current contact element, for example in the form of one or more resilient arms, integrated into the stud holder 44 for applying a welding current to the weld stud 20. The welding gun 40 also has a controller 99 for controlling various components and devices of the welding gun and the welding unit 50. The controller 99 is intended to control one or more parameters of the welding operation. For this purpose, the controller 99 comprises various electronic components, such as, for example, one or more microprocessors, one or more temporary or permanent data memories, etc.

[0019] The welding gun 40 also has a stud lifting device formed as a first lift magnet, which, when activated, moves on the stud holder 44 with a force towards the opening 46 (upward in FIG. 1 ). The control device 99 communicates with the stud lifting device via signal lines, not shown, to control the stud lifting device and, in particular, to activate and deactivate it. The welding gun 40 also has a stud immersion device formed as a spring element or a second lift magnet, which, when activated, moves on the stud holder 44 with a force towards the opening 46 (downward in FIG. 1 ). The control device 99 communicates with the stud immersion device via signal lines, not shown, to control the stud immersion device and, in particular, to activate and deactivate it. If the stud immersion device takes the form of a spring element, this spring element is preferably tensioned when the stud holder is moved backward by the stud lifting device, so that the spring element moves the stud holder forward as soon as the stud lifting device is deactivated.

[0020] In a welding process using the welding apparatus 10, the substrate 30 and the stud 20 are first prepared. In a further step, for example, information regarding desired parameters of the subsequent welding operation is input by a user via an input device. In a further step, a welding current between the weld stud 20 and the substrate 30 is applied to the weld stud 20 by the welding unit 50 using the first cable 61 and the second cable 62. In a further step, the weld stud 20 is lifted off the substrate by a stud lifting device while maintaining the welding current flowing between the weld stud 20 and the substrate 30, forming an arc between the weld stud 20 and the substrate 30. Due to the heat generated by the arc, the material of the weld stud 20 and / or the substrate 30 is then partially liquefied. In a further step, the weld stud 20 is immersed in the liquefied material of the weld stud 20 or the substrate 30 by a stud immersion device. The liquefied material of the weld stud 20 or the substrate 30 then solidifies so that the weld stud 20 is connected to the substrate 30 in an integrally joined manner. The amount of electrical energy used during the welding process, applied to a single weld stud, can be as low as less than 3 kJ.

[0021] 2 shows an article of manufacture, namely a welding assembly 200, comprising a weld stud 220 and a stud holder 244. The weld stud 220 has a shank 240 defining a longitudinal direction 230 and provided with attachment means 250 designed as an external thread, a welding area 260 at its end to be liquefied during the welding process, and a retaining means 270 designed as a circumferentially extending recess, preferably a groove, and arranged in the longitudinal direction 230 between the welding area 260 and the attachment means 250. The stud holder 244 has a retaining device 280 designed as a circumferentially extending protrusion, in which the retaining device 270 engages for holding the weld stud 220 during the welding process, for example using the welding device 10 (FIG. 1).

[0022] The stud holder 244 is part of a welding gun (not shown) for welding the weld stud 220 to the substrate and may, for example, be of a similar design to the welding gun 40 (FIG. 1). The holding device 280 is arranged at the front end of the welding gun, so that the weld stud 220 is advanced towards the substrate when the stud holder 244 is advanced, for example by a stud immersion device. Behind the holding device 280, the welding gun, and in particular the stud holder 244, has a socket 290 designed essentially as a cavity for the attachment means 250 of the weld stud. This arrangement protects the attachment means 250 from damage by the holding device 280, while on the other hand, it ensures that the holding device 280 holds the weld stud in place regardless of the length of the shank 240 of the stud and / or the length of the attachment means 250. Furthermore, it is possible to use a single stud holder for weld studs with different attachment means, in particular attachment means of different sizes.

[0023] In Figure 3, a second welding assembly 300 is shown, which comprises a second weld stud 320 and the stud holder 244 of Figure 2. The second weld stud 320 likewise comprises a shank 340 defining a longitudinal direction 330 and provided with attachment means 350 designed as an external thread, a welding area 360 provided at the end to be liquefied during the welding process, and second retaining means 370 designed as a circumferentially extending recess, which is arranged in the longitudinal direction 330 between the welding area 360 and the attachment means 350 and which has the same shape and dimensions as the retaining means 270 of the weld stud 220 shown in Figure 2.

[0024] The attachment means 350 of the weld stud 320 has a smaller diameter than the attachment means 250 of the weld stud 220, so that when the weld stud 350 is held in engagement with the holding means 370 by the holding device 280, it is similarly received in the socket 290. The weld stud 220 and the second weld stud 320 are therefore part of a fastening system according to the present application. Here, the weld area 260 of the weld stud 220 is identical in shape and size to the weld area 360 of the second weld stud 320. This makes it possible to weld weld studs with different attachment means, in particular different sized attachment means, to a substrate using the same welding parameters, such as welding current strength, voltage, welding current duration, etc.

[0025] The manufactured goods are 0-0.03% carbon, 0.5 to 0.75% silicon, 0-2% magnesium, 0 to 0.045% phosphorus, 0 to 0.012% sulfur, 16-18% chromium and 2.0-2.5% molybdenum, 10-14% nickel, 0-0.1% nitrogen, 0.2-0.7% titanium, the balance being iron and impurities, and incidental amounts of residual elements; The weld studs 200, 300 are manufactured from a steel alloy consisting essentially of the above-proposed steel alloy. In particular, the entire weld stud 200, 300 may consist of the above-proposed steel alloy. Alternatively, the weld region 260, 360 may consist of the above-proposed steel alloy, while the remaining parts of the weld studs 200, 300 may comprise a different material, for example a steel material containing a small amount of silicon and / or titanium. In another embodiment, pellets or similar elements made of a steel alloy may be added to a semi-finished weld stud made of a different material, especially in the weld region. In yet another embodiment, a surface layer, for example a coating, made of a steel alloy may be added to a semi-finished weld stud made of a different material, especially in the weld region.

[0026] The foregoing exemplary embodiments of the present invention have been presented for purposes of illustration and description. This description is not intended to be exhaustive or to limit the invention to the precise form disclosed, as modifications and variations are possible in light of the above teachings or may be acquired from practice of the invention. The described functionality may be distributed among modules differing in number and distribution of functionality from that described herein. In addition, the order of performing the functions may vary depending on the embodiment. The embodiments were chosen and described as practical applications of the invention in order to explain the principles of the invention and to enable those skilled in the art to utilize the invention in various embodiments and with various modifications as suited to the particular uses intended. The scope of the invention is intended to be defined by the claims appended hereto and their equivalents.

Claims

1. 0 to 0.08% carbon; 0-1% silicon, 0-2% manganese, 0 to 0.045% phosphorus; 0 to 0.03% sulfur; 16-20% chromium, 2.0 to 3.0% molybdenum; 8 to 14% nickel, 0 to 0.1% nitrogen; 0 to 0.7% titanium, the balance being iron and impurities, and incidental amounts of residual elements; A steel alloy consisting essentially of:

2. 10. The steel alloy of claim 1, wherein the sum of the amount of silicon and the amount of titanium is at least 0.5%.

3. 3. The steel alloy of claim 2, wherein the sum of the amount of silicon and the amount of titanium is at least 0.5% greater than the amount of carbon.

4. 4. A steel alloy according to any one of claims 1 to 3 containing 0 to 0.03% carbon.

5. 5. A steel alloy according to any one of claims 1 to 4, containing 0.5 to 0.75% silicon.

6. 6. A steel alloy according to any one of claims 1 to 5 containing 0 to 0.012% sulphur.

7. 7. A steel alloy according to any one of the preceding claims containing 16-18% chromium.

8. 8. A steel alloy according to any one of the preceding claims containing 2.0 to 2.5% molybdenum.

9. 9. A steel alloy according to any one of the preceding claims containing 10-14% nickel.

10. A steel alloy according to any one of the preceding claims containing 0.2 to 0.7% titanium.

11. An article of manufacture made from the steel alloy of any one of claims 1 to 10.

12. The article of manufacture of claim 11 , wherein the bulk material of the article comprises the steel alloy.

13. 13. An article of manufacture according to claim 11 or 12, wherein a surface layer or coating of said article consists of said steel alloy.

14. An article of manufacture according to any one of claims 11 to 13, which is a fastening element or a welded stud.

15. 1. A method for welding a weld stud to a substrate, comprising: a) providing a weld stud according to claim 14; b) passing a welding current through the weld stud between the weld stud and the substrate; c) partially liquefying the material of the weld stud and / or the substrate; d) solidifying the liquefied material of the weld stud and / or the substrate; and e) dipping the weld stud into the liquefied material of the weld stud and / or the substrate before the liquefied material solidifies; A method comprising:

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