Optimized welding method for stainless steel composite plate

Abstract

The invention discloses an optimized welding method for a stainless steel composite plate, the stainless steel composite plate comprises a base material layer and a stainless steel composite material layer, and a transition layer is arranged at the bonding interface of the base material layer and the stainless steel composite material layer; the optimized welding method comprises the steps that a trapezoid groove is machined in the position, corresponding to the base material layer, of the welding section of the stainless steel composite plate; a V-shaped groove is formed in the position, corresponding to the transition layer and the stainless steel composite material layer, of the welding section of the stainless steel composite plate; welding the stainless steel composite material layer by adopting single tungsten electrode argon arc welding; welding the transition layer by adopting single tungsten electrode argon arc welding; and welding the base material layer by adopting single tungsten electrode argon arc welding. According to the method, the using amount of stainless steel welding materials is reduced, the welding cost is reduced, the welding efficiency is improved, and meanwhile the high strength of the connector is effectively guaranteed. In addition, the method adopted by the invention is low in equipment requirement, simple to operate, correspondingly low in assembly precision requirement and high in applicability in an engineering operation site.

Description

Technical Field

[0001] The invention relates to a welding method, in particular to a welding method for a stainless steel composite plate. Background Art

[0002] In engineering, a few multi-layer and multi-pass welding scenes of stainless steel composite plate components require a specific welding sequence, namely composite layer-transition layer-base material layer. At this time, if conventional welding processes are used (i.e. carbon steel welding materials are used for carbon steel in the base material layer and stainless steel welding materials are used for stainless steel in the composite layer), the carbon steel weld bead welded later can easily melt a large amount of alloy elements into the stainless steel welding materials, resulting in overall hardness and brittleness (the structure is transformed into martensite structure), which greatly reduces the mechanical properties of the joint.

[0003] However, this welding sequence has to be adopted in some production conditions in the project, such as the girth welding connection of small oil and gas pipelines. To solve this problem, technicians can only use stainless steel welding materials for the entire weld. For example, the national standard "Technical Requirements for Welding of Stainless Steel Composite Plates" (GB / T 13148-2008) explains the welding of composite plates under this welding sequence. At this time, the welding of the base material layer weld should use stainless steel welding wire with performance matching that of the composite layer.

[0004] However, this approach has several disadvantages. First, it greatly increases the amount of stainless steel filler metal, greatly increases welding costs and reduces welding efficiency; second, the yield strength of the weld will also decrease, which will increase the risk of failure of the stainless steel composite plate joint when subjected to large loads.

[0005] In addition, a Chinese patent document with publication number CN112122783A, publication date December 25, 2020, and titled "A method for laser butt welding of carbon steel-nickel alloy composite plates" proposes using laser self-melting or wire welding to achieve the connection of composite layers under conditions where construction space is limited and the composite layer must be welded first. However, it focuses on the problem that the composite plate cannot be welded on one side under this welding sequence, and does not pay attention to the performance changes of the mixed weld of nickel-based alloy and carbon steel.

[0006] In addition, a Chinese patent document with publication number CN113042895B, publication date April 26, 2022, and titled “A welding method for a nickel-steel composite structure” proposes that when the composite layer is welded first, laser autogenous welding is also used to complete the connection of the composite layer, and then cold metal transition welding is used to weld the adjacent welds, thereby completing the connection of the nickel-based alloy composite plate under this welding sequence. However, it mainly targets the problem of decreased corrosion resistance of the composite layer caused by element migration at the interface between the composite layer and the substrate layer, and also does not solve the problem of decreased toughness of the mixed weld of nickel-based alloy and carbon steel.

[0007] In addition, the above methods all use laser self-melting or wire welding when welding composite plates. This type of welding method has very high requirements on the assembly accuracy of components and is difficult to apply in on-site working environments. In addition, the equipment is expensive, the operation is cumbersome, and maintenance is difficult. Summary of the invention

[0008] The object of the present invention is to provide an optimized welding method for stainless steel composite plates. The method can significantly reduce the dilution rate of the first layer of weld bead that is in direct contact with the transition layer in the welding sequence of composite layer-transition layer-base material layer through a special groove design and based on a common tungsten inert gas arc welding method, thereby controlling the structure of the first layer of weld bead to be the parent material structure, thereby achieving reliable connection of the composite plate.

[0009] In order to achieve the above object, the present invention provides an optimized welding method for a stainless steel composite plate, wherein the stainless steel composite plate comprises a substrate layer and a stainless steel composite layer, and a transition layer is provided at the bonding interface between the substrate layer and the stainless steel composite layer; the optimized welding method comprises the steps of:

[0010] A stepped groove is processed at the position corresponding to the base material layer on the welding section of the stainless steel composite plate; a V-shaped groove is opened at the position corresponding to the transition layer and the stainless steel composite material layer on the welding section of the stainless steel composite plate;

[0011] The stainless steel composite layer is welded by single tungsten electrode argon arc welding;

[0012] The transition layer is welded by single tungsten-arc argon welding;

[0013] The base material layer is welded by single tungsten inert gas arc welding.

[0014] Furthermore, in the optimized welding method for stainless steel composite plates described in the present invention, the angle between the inclined portion of the trapezoidal groove and the vertical direction is consistent with the angle between the inclined portion of the V-shaped groove and the vertical direction.

[0015] Furthermore, in the optimized welding method for stainless steel composite plates described in the present invention, the angle between the inclined portion of the V-shaped groove and the vertical direction and the angle between the inclined portion of the trapezoidal groove and the vertical direction are both α, and the value range is 15-25°.

[0016] In this embodiment, in order to take into account the operability of the tungsten inert gas welding torch and the groove filling amount and filling efficiency, the angle between the inclined portion of the trapezoidal groove and the vertical direction and the angle α between the inclined portion of the V-shaped groove and the vertical direction can be controlled between 15-25°.

[0017] Furthermore, in the optimized welding method for stainless steel composite plates of the present invention, the distance b3 between the step plane of the trapezoidal groove and the bonding interface between the substrate layer and the stainless steel composite layer is 1-1.5 mm.

[0018] Furthermore, in the optimized welding method for stainless steel composite plates described in the present invention, the single-side width of the step of the trapezoidal groove w1≥1.5((b2+b3)×tanα+w2 / 2), where b2 represents the distance between the surface of the stainless steel composite layer and the bonding interface between it and the substrate layer, and its unit parameter is mm, α represents the angle between the inclined portion of the trapezoidal groove and the vertical direction, and w2 represents the assembly gap.

[0019] In this embodiment, the distance b3 between the step plane of the groove and the bonding interface between the substrate layer and the stainless steel composite layer can be controlled to be between 1-1.5 mm, and the step single-side width w1 of the groove is ≥ 1.5 ((b2+b3)×tanα+w2 / 2), which can ensure that the ratio of the width of the subsequent first layer of weld bead directly contacting the transition layer to its molten width is less than 40%, which will help to control the low dilution rate of each weld bead in this layer. In addition, the step design of the groove also has a good flatness on the surface to be welded while obtaining a low dilution rate, which will be conducive to the good formation of the weld.

[0020] Furthermore, in the optimized welding method for stainless steel composite plates described in the present invention, the assembly gap w2 is 1-3 mm.

[0021] Furthermore, in the optimized welding method for stainless steel composite plates described in the present invention, in the step of welding the stainless steel composite layer using single tungsten electrode argon arc welding: a solid stainless steel welding wire matching the stainless steel composite layer is used, and pure argon gas (purity not less than 99%) is used for protection, the welding voltage is controlled to be 9.0-11V, the welding current is 60-90A, the welding speed is 75-100mm / min, and the wire feeding speed is 0.6-0.9m / min.

[0022] Furthermore, in the optimized welding method for stainless steel composite plates described in the present invention, in the step of welding the transition layer using single tungsten electrode argon arc welding: a solid stainless steel welding wire matching the stainless steel composite layer is used, and pure argon gas (purity not less than 99%) is used for protection, the welding voltage is controlled to be 10-13V, the welding current is 100-130A, the welding speed is 80-110mm / min, and the wire feeding speed is 0.5-0.8m / min.

[0023] In this embodiment, the welding process is adopted to ensure that the transition layer weld has good welding forming, and the flat surface to be welded will be beneficial to the forming control of the first layer weld bead in contact with the transition layer.

[0024] Furthermore, in the step of welding the substrate layer by single tungsten electrode argon arc welding in the optimized welding method for stainless steel composite plates of the present invention:

[0025] First, weld the first layer of weld bead that contacts the transition layer: this layer is welded in two equal passes, the shielding gas is argon + CO2 mixed gas, and a flux-cored wire that matches the base material layer is used;

[0026] Complete the welding of other welds of the base material layer: the shielding gas adopts pure argon gas (purity not less than 99%), and the welding wire adopts solid carbon steel welding wire matching the base material layer.

[0027] In this embodiment, the overlap rate between each weld and the transition layer weld can be controlled to be 50%.

[0028] Furthermore, in the optimized welding method for stainless steel composite plates described in the present invention, when welding the first layer of the base material layer: the welding voltage is controlled to be 14-15.5V, the welding current is 140-160A, the welding speed is 120-140mm / min, and the wire feeding speed is 2.5-2.8m / min.

[0029] Furthermore, in the optimized welding method for stainless steel composite plates described in the present invention, when welding other welds of the substrate layer: the welding voltage is controlled to be 14-16V, the welding current is 250-280A, the welding speed is 150-180mm / min, and the wire feeding speed is 2.6-3.0m / min.

[0030] Furthermore, in the optimized welding method for stainless steel composite plates described in the present invention, when welding the first layer of welds: the distance between the center of the welding gun and the step edge of the trapezoidal groove in the width direction is controlled to be (w1+(b2+b3)tanα+w2 / 2) / 2 during each welding, wherein b2 is the distance between the surface of the stainless steel composite layer and the bonding interface between it and the substrate layer, b3 is the distance between the step plane of the trapezoidal groove and the bonding interface between the substrate layer and the stainless steel composite layer, w1 is the single-side width of the step of the trapezoidal groove, w2 is the assembly gap, and the unit parameters are all mm, and α represents the angle between the inclined portion of the trapezoidal groove and the vertical direction.

[0031] In this embodiment, the dilution level of the base material layer weld bead relative to the composite material layer weld can be lower than 4.0%, thereby ensuring that the structure of the weld bead does not produce martensite and still maintains good plasticity and toughness.

[0032] The optimized welding method of the stainless steel composite plate of the present invention has the following advantages and beneficial effects compared with the prior art:

[0033] The welding method of the present invention can significantly reduce the dilution rate of the first layer of weld bead that is in direct contact with the transition layer in the welding sequence of composite material layer-transition layer-base material layer, thereby controlling the structure of the first layer of weld bead to be the structure of the base material, thereby achieving reliable connection of the composite plate.

[0034] In addition, in the preferred embodiment of the present invention, due to the use of mixed welding materials for filling, compared with the prior art, the use of stainless steel welding materials is reduced, the welding cost is reduced, and the welding efficiency is improved, while the high strength of the joint is effectively guaranteed.

[0035] In addition, the method adopted by the present invention has low equipment requirements, simple operation, and correspondingly low requirements for assembly accuracy, and has strong applicability in engineering operation sites. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 The schematic diagram of the groove used in the optimized welding method of the stainless steel composite plate of the present invention is schematically shown.

[0037] Figure 2 The cross-sectional morphology of the welded joint prepared by the optimized welding method of Example 1 of the present invention is shown.

[0038] Figure 3 The microstructure photograph of the first layer weld interface of the transition layer / carbon steel substrate layer in the weld joint prepared by the optimized welding method of Example 1 of the present invention is shown. DETAILED DESCRIPTION

[0039] The optimized welding method of the stainless steel composite plate of the present invention will be further explained and illustrated below in conjunction with specific embodiments and the accompanying drawings of the specification. However, such explanation and illustration do not constitute an improper limitation on the technical solution of the present invention.

[0040] Figure 1 Shows two joined stainless steel composite panels A and B. Figure 1 The dotted line O in the figure represents a joint. The stainless steel composite plate comprises a carbon steel substrate layer 1 and a stainless steel composite material layer 2, and a transition layer is provided at the bonding interface between the carbon steel substrate layer 1 and the stainless steel composite material layer 2. Figure 1 The symbol "b1" represents the distance between the surface of the carbon steel substrate layer and the bonding interface between it and the stainless steel composite layer, and the symbol "b2" represents the distance between the surface of the stainless steel composite layer and the bonding interface between it and the carbon steel substrate layer.

[0041] In a specific embodiment, a stainless steel composite plate with a grade of SUS304 / Q235 can be used, that is, the base material is Q235, and the stainless steel composite material is SUS304. The thickness of the stainless steel composite plate is 10 mm, wherein b1 of the stainless steel composite plate is 8 mm, and b2 is 2 mm.

[0042] In some embodiments, an optimized welding method for stainless steel composite plates may include the steps of:

[0043] 100: Processing at the welding position of two spliced ​​stainless steel composite plates A and B as follows Figure 1The groove shown. Wherein, a trapezoidal groove is processed at a position corresponding to the carbon steel substrate layer on the welding section of the stainless steel composite plate, and the trapezoidal groove includes an inclined portion 7 and a step 8 of the trapezoidal groove arranged in sequence, wherein the single-side width of the step 8 of the trapezoidal groove is represented by w1. In some more specific embodiments, the single-side width w1 of the step 8 of the trapezoidal groove is ≥1.5((b2+b3)×tanα+w2 / 2).

[0044] The distance between the plane of the step 8 of the trapezoidal groove and the bonding interface between the substrate layer and the stainless steel composite layer is Figure 1 In some more specific embodiments, the distance b3 between the plane of the step 8 of the trapezoidal groove and the bonding interface between the substrate layer and the stainless steel composite layer can be controlled to be between 1 and 1.5 mm.

[0045] By controlling the single-side width w1 of the step of the trapezoidal groove and the distance b3 between the step plane of the trapezoidal groove and the bonding interface between the base material layer and the stainless steel composite layer, it can be ensured that the ratio of the width of the subsequent first layer of weld bead directly in contact with the transition layer to its molten width is less than 40%, which will help control the low dilution rate of each weld bead in this layer. In addition, the step design of the groove also has a good flatness on the surface to be welded while obtaining a low dilution rate, which will be conducive to the good formation of the weld.

[0046] A V-shaped groove is formed on the welding section of the stainless steel composite plate at positions corresponding to the transition layer and the stainless steel composite layer, and the V-shaped groove has an inclined portion 9. The angle between the inclined portion 7 of the trapezoidal groove and the vertical direction and the angle between the inclined portion 9 of the V-shaped groove and the vertical direction are both α. In some more specific embodiments, the value range of α can be 15-25° to improve the operability of the tungsten inert gas arc welding torch and the groove filling amount and filling efficiency.

[0047] Assembly clearance Figure 1 In some more specific embodiments, the assembly gap w2 may be 1-3 mm.

[0048] 200: The stainless steel composite layer 2 is welded by single tungsten electrode argon arc welding to obtain a composite layer weld 3. The welding shielding gas adopts pure argon gas with a purity of not less than 99%, and a stainless steel solid welding wire matching the stainless steel composite layer is used for welding; the welding process parameters can be controlled as follows: the welding voltage is controlled to be 9.0-11V, the welding current is controlled to be 60-90A, the welding speed is controlled to be 75-100mm / min, and the wire feeding speed is controlled to be 0.6-0.9m / min.

[0049] 300: The transition layer is welded by single tungsten electrode argon arc welding to obtain a transition layer weld 4. During welding, the shielding gas is pure argon gas with a purity of not less than 99%, and the welding material is a stainless steel solid welding wire that matches the stainless steel composite layer; the welding process parameters can be controlled as follows: welding voltage is 10-13V, welding current is 100-130A, welding speed is 80-110mm / min, and wire feeding speed is 0.5-0.8m / min.

[0050] By adopting the above welding process, it can be ensured that the transition layer weld has good welding forming, and the flat surface to be welded will be conducive to the forming control of the first layer weld bead contacting the transition layer.

[0051] 400: Single tungsten inert gas arc welding is used to weld the base material layer: First, the first layer of weld bead 5 in contact with the transition layer is welded: this layer is welded in two equal passes, the shielding gas is argon + CO2 mixed gas, such as 78% Ar + 18% CO2, and the welding material is a flux-cored wire that matches the carbon steel base material layer. Then, the welding of other weld bead 6 of the base material layer is completed: the shielding gas is pure argon with a purity of not less than 99%, and the welding wire is a carbon steel solid welding wire that matches the base material layer.

[0052] In this embodiment, the overlap rate between each weld and the transition layer weld can be controlled to be 50%.

[0053] In some more specific embodiments, when welding the first layer of weld bead 5: the welding voltage is controlled to be 14-15.5V, the welding current is 140-160A, the welding speed is 120-140mm / min, and the wire feeding speed is 2.5-2.8m / min.

[0054] In addition, in some more specific embodiments, when welding the first layer of weld 5: the distance between the center of the welding gun and the step edge of the trapezoidal groove in the width direction can be controlled to be (w1+(b2+b3)tanα+w2 / 2) / 2 during each welding.

[0055] In some more specific embodiments, when welding other welds of the carbon steel substrate layer: the welding voltage can be controlled to be 14-16V, the welding current to be 250-280A, the welding speed to be 150-180mm / min, and the wire feeding speed to be 2.6-3.0m / min.

[0056] By adopting the above embodiment, the dilution level of the carbon steel substrate layer weld relative to the stainless steel composite layer weld can be further reduced to less than 4.0%, thereby further ensuring that the structure of the weld will not produce martensite and still maintain good plasticity and toughness.

[0057] In order to further reflect the technical effects of the preferred implementation of this case, Table 1 lists the characteristic parameters of the grooves used in the preferred embodiments 1-5 of the present invention.

[0058] Table 1.

[0059] Example Groove angle α(°) <![CDATA[b3(mm)]]> <![CDATA[w1(mm)]]> <![CDATA[w2(mm)]]> Example 1 15 1 3 2 Example 2 18 1 3 2 Example 3 25 1.2 4 1 Example 4 15 1.5 2.5 1.5 Example 5 20 1 4 3

[0060] Table 2 lists the welding process parameters used in the steps of forming the stainless steel composite layer weld in preferred embodiments 1-5 of the present invention.

[0061] Table 2.

[0062]

[0063] Table 3 lists the welding process parameters used in the steps of forming the transition layer weld in preferred embodiments 1-5 of the present invention.

[0064] Table 3.

[0065]

[0066]

[0067] Table 4 lists the welding process parameters used in the steps of forming the first weld bead of the carbon steel substrate layer in preferred embodiments 1-5 of the present invention.

[0068] Table 4.

[0069]

[0070] Table 5 lists the welding process parameters used in the steps of forming other welds of the carbon steel substrate layer in preferred embodiments 1-5 of the present invention.

[0071] Table 5.

[0072]

[0073] In addition, in order to prove the implementation effect of the preferred embodiment, Table 6 lists the Cr element content of each layer of the base material and the weld in the welded joint of the stainless steel composite plate welded by Example 1 of the present invention, and the dilution rate of the first layer of carbon steel weld 5 directly in contact with the transition layer is calculated to be 2.4%. Therefore, the martensitic structure of the carbon steel base material layer weld can be avoided.

[0074] Table 6.

[0075]

[0076] Figure 2 The cross-sectional morphology of the optimized joint prepared by the optimized welding method of Example 1 of the present invention is shown.

[0077] from Figure 2 It can be seen from the figure that the welded joint is well bonded and there are no welding defects.

[0078] Figure 3 The microstructure photographs on both sides of the first layer weld interface of the transition layer / carbon steel substrate layer in the weld joint prepared by the optimized welding method of Example 1 of the present invention are shown.

[0079] from Figure 3 It can be seen that the transition layer weld still maintains the parent phase austenite structure and cannot be corroded by nitric acid alcohol. At the same time, the structure of the first layer weld of the carbon steel base layer still maintains the parent phase ferrite structure of the welding material itself. The joint structure transition is good and the connection is reliable.

[0080] It should be noted that the combination of the various technical features in this case is not limited to the combination described in the claims of this case or the combination described in the specific embodiments. All technical features recorded in this case can be freely combined or combined in any way unless there is a contradiction between them.

[0081] It should also be noted that the above-listed embodiments are only specific embodiments of the present invention. Obviously, the present invention is not limited to the above embodiments, and similar changes or modifications made therewith can be directly derived or easily associated with the contents disclosed by those skilled in the art from the present invention, and all should belong to the protection scope of the present invention.

Claims

1. An optimized welding method for a stainless steel composite plate, wherein the stainless steel composite plate comprises a substrate layer and a stainless steel composite layer, wherein a transition layer is provided at a bonding interface between the substrate layer and the stainless steel composite layer; characterized in that: The optimized welding method comprises the steps of: A trapezoidal groove is processed at the position corresponding to the base material layer on the welding section of the stainless steel composite plate; a V-shaped groove is opened at the position corresponding to the transition layer and the stainless steel composite layer on the welding section of the stainless steel composite plate; The stainless steel composite layer is welded by single tungsten electrode argon arc welding; The transition layer is welded by single tungsten-arc argon welding; The base material layer is welded by single tungsten inert gas arc welding.

2. The optimized welding method for stainless steel composite plate according to claim 1, characterized in that: The angle between the inclined portion of the trapezoidal groove and the vertical direction is consistent with the angle between the inclined portion of the V-shaped groove and the vertical direction.

3. The optimized welding method for stainless steel composite plate according to claim 2, characterized in that: The angle between the inclined portion of the V-shaped groove and the vertical direction and the angle between the inclined portion of the trapezoidal groove and the vertical direction are both α, and the value range is 15-25°.

4. The optimized welding method for stainless steel composite plate according to claim 1, characterized in that: The distance b3 between the step plane of the trapezoidal groove and the bonding interface between the substrate layer and the stainless steel composite layer is 1-1.5 mm.

5. The optimized welding method for stainless steel composite plate according to claim 4, characterized in that: The single-side width of the step of the trapezoidal groove w1≥1.5((b2+b3)×tanα+w2 / 2), where b2 represents the distance between the surface of the stainless steel composite layer and the bonding interface between it and the substrate layer, and its unit parameter is mm, α represents the angle between the inclined portion of the trapezoidal groove and the vertical direction, and w2 represents the assembly gap.

6. The optimized welding method for stainless steel composite plate according to claim 1, characterized in that: The assembly gap w2 is 1-3mm.

7. The optimized welding method for stainless steel composite plate according to claim 1, characterized in that: In the step of welding the stainless steel composite layer by single tungsten electrode argon arc welding: use a stainless steel solid welding wire that matches the stainless steel composite layer, use pure argon gas for protection, control the welding voltage to 9.0-11V, the welding current to 60-90A, the welding speed to 75-100mm / min, and the wire feeding speed to 0.6-0.9m / min.

8. The optimized welding method for stainless steel composite plate according to claim 1, characterized in that: In the step of welding the transition layer using single tungsten electrode argon arc welding: use a stainless steel solid welding wire that matches the stainless steel composite layer, use pure argon gas for protection, control the welding voltage to 10-13V, the welding current to 100-130A, the welding speed to 80-110mm / min, and the wire feeding speed to 0.5-0.8m / min.

9. The optimized welding method for stainless steel composite plate according to claim 1, characterized in that: In the steps of welding the base material layer by single tungsten inert gas arc welding: First, weld the first layer of weld bead that contacts the transition layer: this layer is welded in two equal passes, the shielding gas is argon + CO2 mixed gas, and a flux-cored wire that matches the base material layer is used; Complete the welding of other welds of the base material layer: the shielding gas adopts pure argon gas, and the welding wire adopts solid carbon steel welding wire matching the base material layer.

10. The optimized welding method for stainless steel composite plate according to claim 9, characterized in that: When welding the first layer of weld: control the welding voltage to 14-15.5V, the welding current to 140-160A, the welding speed to 120-140mm / min, and the wire feeding speed to 2.5-2.8m / min.

11. The optimized welding method for stainless steel composite plate according to claim 9, characterized in that: When welding other welds of the base material layer: control the welding voltage to 14-16V, the welding current to 250-280A, the welding speed to 150-180mm / min, and the wire feeding speed to 2.6-3.0m / min.

12. The optimized welding method for stainless steel composite plate according to claim 9, characterized in that: When welding the first layer of welds: during each weld, the distance between the center of the welding gun and the step edge of the trapezoidal groove in the width direction is controlled to be (w1+(b2+b3)tanα+w2 / 2) / 2, where b2 is the distance from the surface of the stainless steel composite layer to the bonding interface between it and the substrate layer, b3 is the distance between the step plane of the trapezoidal groove and the bonding interface between the substrate layer and the stainless steel composite layer, w1 is the single-side width of the step of the trapezoidal groove, w2 is the assembly gap, and the unit parameters are all mm, and α represents the angle between the inclined portion of the trapezoidal groove and the vertical direction.

Images