阅读说明：本技术 基于多丝埋弧焊的低碳微合金钢高热输入焊接性评估方法 (Low-carbon micro-alloy steel high-heat input weldability evaluation method based on multi-wire submerged arc welding ) 是由 刘硕 于 2020-05-27 设计创作，主要内容包括：本发明涉及一种基于多丝埋弧焊的低碳微合金钢高热输入焊接性评估方法,其步骤依次包括：选用试验板为低碳微合金钢板；低碳微合金埋弧焊丝和碱性烧结焊剂配合使用；所述一对试验板进行平焊位置对接焊,其坡口形式为一侧直边的带钝边双V型坡口,且在坡口背面设置同质垫板,所述钝边向外偏折形成下V型坡口,下V型坡口向外偏折形成上V型坡口,下V型坡口与坡口中心轴线成角α,上V型坡口与坡口中心轴线成角β；采用多丝自动埋弧焊接的方式对试验板进行焊接,多丝包括前丝、中丝和后丝,多丝同时共熔池焊接；完成焊接后,观察和检测焊接接头的裂纹倾向以评估材料的工艺焊接性,并通过焊接接头的力学性能检测以评估材料的使用焊接性。(The invention relates to a low-carbon micro-alloy steel high-heat input weldability assessment method based on multi-wire submerged arc welding, which sequentially comprises the following steps: selecting a test plate as a low-carbon microalloy steel plate; the low-carbon microalloy submerged arc welding wire and the alkaline sintered flux are matched for use; the pair of test plates are subjected to butt welding at flat welding positions, the grooves are in the form of double V-shaped grooves with truncated edges and straight edges at one side, homogeneous backing plates are arranged on the back surfaces of the grooves, the truncated edges are outwards deflected to form lower V-shaped grooves, the lower V-shaped grooves are outwards deflected to form upper V-shaped grooves, the lower V-shaped grooves and the central axes of the grooves form an angle alpha, and the upper V-shaped grooves and the central axes of the grooves form an angle beta; welding the test board by adopting a multi-wire automatic submerged arc welding mode, wherein the multi-wire comprises a front wire, a middle wire and a rear wire, and the multi-wire is simultaneously welded in a eutectic pool; after the welding is completed, the crack tendency of the welded joint is observed and detected to evaluate the process weldability of the material, and the service weldability of the material is evaluated by the mechanical property detection of the welded joint.)

1. A low-carbon micro-alloy steel high-heat input weldability assessment method based on multi-wire submerged arc welding is characterized in that: the method comprises the following steps:

selecting a test plate as a low-carbon microalloy steel plate, wherein the thickness t of the steel plate is more than or equal to 40 mm;

selecting a low-carbon micro-alloy submerged arc welding wire and an alkaline sintered flux, wherein the diameter of the welding wire is 4.0-6.0 mm;

step three, butt welding the flat welding positions of the pair of test plates, wherein the grooves are double V-shaped grooves with truncated edges, one side of each groove is straight, the truncated edges are outwards deflected to form a lower V-shaped groove, the lower V-shaped groove is outwards deflected to form an upper V-shaped groove, the lower V-shaped groove forms an angle alpha with the central axis of the groove, the upper V-shaped groove forms an angle beta with the central axis of the groove, and a homogeneous base plate is arranged on the back of the groove, wherein alpha is 40-65 degrees, beta is 25-45 degrees, the height a of the truncated edge is 5-11 mm, the height b of the lower V-shaped groove is 11-25 mm, b is smaller than 1/3 of the thickness t of the steel plate, the thickness c of the base plate is 12-25 mm, the width d of the base plate covering groove is 80-400 mm, and the pairing gap of the test plates is 0-1 mm;

welding the test board by adopting a multi-wire automatic submerged arc welding mode, wherein the multi-wire comprises a front wire, a middle wire and a rear wire, and the multi-wire is simultaneously welded in a eutectic pool, wherein:

the welding process parameters used were: the welding heat input E is 5.0-10.0 kJ/mm; welding current I of front wire_{Front side}And the diameter R of the front filament_{Front side}Has a relationship of_{Front side}＝(150～250)R_{Front side}(ii) a Welding current I of medium wire_InAnd the diameter R of the medium thread_InHas a relationship of_In＝(140～200)R_In(ii) a Welding current I of rear wire_{Rear end}And rear filament diameter R_{Rear end}Has a relationship of_{Rear end}＝(110～180)R_{Rear end}(ii) a The welding voltage of each wire is respectively matched with the welding current and the dry elongation of the welding wire, and the combination of the welding current, the welding voltage and the welding traveling speed of each wire can be matched with the welding heat input value required by the test;

during welding, the front wire welding gun faces along the welding directionFront inclination angle is delta₁The backward inclination angle of the medium wire welding gun is delta from 5 degrees to 25 degrees₂0-10 DEG backward inclination angle delta of the rear wire welding gun₃10-30 degrees; forming an included angle theta between the front wire welding gun and the straight side of the groove by 5-20 degrees along the width direction of the groove, wherein the middle wire welding gun and the rear wire welding gun are both vertically arranged; the distance L between each wire end and the straight side of the groove is equal to E/1.5+2.0, the unit of L is mm, and E is welding heat input;

and step five, obtaining a welding joint after welding, observing and detecting the crack tendency of the welding joint to evaluate the technological weldability of the material, and evaluating the service weldability of the material through the mechanical property detection of the welding joint.

2. The method for evaluating the high heat input weldability of low carbon micro alloy steel based on multi-wire submerged arc welding according to claim 1, characterized in that: in the welding process parameters of the fourth step: the welding current of the front wire is 650-1500A, and the welding voltage is 30-40V; the welding current of the middle wire is 600-1200A, and the welding voltage is 33-42V; the welding current of the rear wire is 450-1000A, and the welding voltage is 35-44V; the welding walking speed of each welding wire is 700-1200 mm/min, and the distance between the welding wires is 20-40 mm.

3. The method for evaluating the high heat input weldability of low carbon micro alloy steel based on multi-wire submerged arc welding according to claim 1, characterized in that: and in the fifth step, the mechanical property detection comprises the detection of low-temperature impact and fracture toughness of a coarse crystal area of a welding heat affected zone adjacent to the single-side straight-edge fusion line.

Technical Field

The invention relates to a microalloy steel welding technology, in particular to a method for evaluating the high heat input weldability of low-carbon microalloy steel based on multi-wire submerged arc welding.

Background

For an important engineering structure using low-carbon microalloy steel, welding is a key process of field installation and construction, the welding quality and efficiency also determine the quality and efficiency of an engineering project, and the quality of the field weldability of the low-carbon microalloy steel material directly influences the quality and safety service of a welded joint. Generally, the weldability of a material includes process weldability, which mainly refers to the ability to avoid welding defect problems (including various types of welding crack sensitivity) and obtain a continuous and complete welding joint during welding, and use weldability, which mainly refers to the use properties (including mechanical properties such as strength, plasticity, toughness and the like) of the welding joint.

In the important industrial fields of a large number of low-carbon microalloyed steel thick plates, such as ship manufacturing, ocean engineering structures, pressure vessels, high-grade building structures and the like, in the manufacturing and construction process, in order to improve the welding efficiency, the heat input is generally higher than 5.0kJ/mm, and the welding heat input has an important influence on the welding heating and cooling process of the low-carbon microalloyed steel with a certain specification, so that the solid phase change and the microstructure evolution of a joint are influenced, and the integral service performance and the service safety of the joint are finally determined. Meanwhile, for the thick-wall low-carbon microalloy steel plate, the crack sensitivity is different under different welding heat input conditions, and different technological weldability is shown. In view of this, a safe, reliable and complete weldability evaluation method close to the field construction conditions is required for the low-carbon micro-alloy steel thick plate.

At present, many methods for evaluating weldability, i.e. weld crack sensitivity, of a steel material process are available, such as: the ISO17642-2 standard provides a TEKKEN test for evaluating the cold crack sensitivity of a plate, which is similar to the oblique Y-shaped groove welding crack test method described in GB 4675.1, welding of a small-scale test welding seam is carried out under a high constraint condition, so that the cold crack sensitivity of a material under a certain welding condition is evaluated, however, the constraint condition of the test method is too harsh, and the test welding seam is a single welding seam with an irregular shape, so that high welding residual stress exists, and cold cracks are more favorably induced. GB/T13817 provides a rigidity restraint welding crack test method, which completely fixes a test steel plate on a bottom plate with a very large thickness, residual stress cannot be released in the welding process, cold cracks are easily induced in a joint area, the method is also conservative, and the welding joint type is also greatly different from the common joint type of a low-carbon microalloy steel structure, and the method does not have a direct field construction welding guidance function. An improved oblique Y-shaped groove welding crack sensitivity test specimen disclosed in Chinese patent 201611208203.5 and a manufacturing method thereof, and a constrained weld manufacturing method for an oblique Y-shaped groove welding crack test disclosed in Chinese patent 201510012348.7 can only solve the problem of indirect evaluation of weldability under certain conditions. The patent and non-patent documents disclosed above are both focused on indirect evaluation of process weldability, have certain referential significance for on-site welding construction of low-carbon microalloy steel structures, but have no direct guidance, mainly cannot consider use weldability, have larger difference from high-heat input welding conditions, and have larger difference between the design form of joints and implementation details of welding process methods and the construction welding conditions of the mainstream low-carbon microalloy steel structures.

Chinese patent 201410516996.1 discloses a steel plate welding method for an ocean platform, and Chinese patent 201110181417.9 discloses a submerged arc welding process for a T-shaped joint of an extra-thick steel plate, both of which adopt a general K-shaped groove form, if the implementation process of the welding process is properly controlled, a fusion line with certain straightness on one side can be obtained after welding, and the requirements of CGHAZ position impact and fracture toughness sampling are met, but the welding process is a specific extra-thick plate (for example, 50-150 mm) product structure and has no universality in various industrial fields. Meanwhile, the method does not relate to the guarantee measure of the straightness of the single-side straight-edge fusion line, when the steel plate is thick, the straightness of the fusion line after welding is easy to guarantee, and when the steel plate is thin, the welding pool is easy to destroy the straightness of the fusion line. In addition, chinese patent 201510385434.2 discloses a CTOD process test method for a large thick plate welding repair joint, and chinese patent 201510605044.1 discloses a welding repair CTOD test method, both of which have certain characteristics of a single-side straight-edge weld line even when the plate thickness is thick, but both of which belong to repair processing measures after defects are found in a finished product welded part, and cannot meet the requirements of low-carbon microalloyed steel in a certain welding heat input range with universality for simultaneously evaluating process weldability and using weldability.

In addition, in the field of double-wire or multi-wire automatic submerged arc welding, chinese patent 201710439703.8 discloses a double-wire submerged arc welding method for high-strength extra-thick steel plates for high heat input welding, and chinese patent 201410009083.0 discloses a preparation method for high weather-resistant multi-wire submerged arc welded steel pipes for marine environments, both of which are specific industrial fields and materials, adopt asymmetric X-shaped grooves, and provide a solution for manufacturing specific products by using technical advantages of double-wire or multi-wire submerged arc welding, and also can not meet the requirements of low-carbon microalloyed steel with universality for simultaneously evaluating technological weldability and using weldability within a certain welding heat input range.

Disclosure of Invention

The invention aims to provide a low-carbon microalloy steel high-heat input weldability assessment method based on multi-wire submerged arc welding.

The invention is realized by the following steps:

a low-carbon micro-alloy steel high-heat input weldability evaluation method based on multi-wire submerged arc welding comprises the following steps:

selecting a test plate as a low-carbon microalloy steel plate, wherein the thickness t of the steel plate is more than or equal to 40 mm;

selecting a low-carbon micro-alloy submerged arc welding wire and an alkaline sintered flux, wherein the diameter of the welding wire is 4.0-6.0 mm;

step three, butt welding the flat welding positions of the pair of test plates, wherein the grooves are double V-shaped grooves with truncated edges, one side of each groove is straight, the truncated edges are outwards deflected to form a lower V-shaped groove, the lower V-shaped groove is outwards deflected to form an upper V-shaped groove, the lower V-shaped groove forms an angle alpha with the central axis of the groove, the upper V-shaped groove forms an angle beta with the central axis of the groove, and a homogeneous base plate is arranged on the back of the groove, wherein alpha is 40-65 degrees, beta is 25-45 degrees, the height a of the truncated edge is 5-11 mm, the height b of the lower V-shaped groove is 11-25 mm, b is smaller than 1/3 of the thickness t of the steel plate, the thickness c of the base plate is 12-25 mm, the width d of the base plate covering groove is 80-400 mm, and the pairing gap of the test plates is 0-1 mm;

welding the test board by adopting a multi-wire automatic submerged arc welding mode, wherein the multi-wire comprises a front wire, a middle wire and a rear wire, and the multi-wire is simultaneously welded in a eutectic pool, wherein:

the welding process parameters used were: the welding heat input E is 5.0-10.0 kJ/mm; welding current I of front wire_{Front side}And the diameter R of the front filament_{Front side}Has a relationship of_{Front side}＝(150～250)R_{Front side}(ii) a Welding current I of medium wire_InAnd the diameter R of the medium thread_InHas a relationship of_In＝(140～200)R_In(ii) a Welding current I of rear wire_{Rear end}And rear filament diameter R_{Rear end}Has a relationship of_{Rear end}＝(110～180)R_{Rear end}(ii) a The welding voltage of each wire is respectively matched with the welding current and the dry elongation of the welding wire, and the combination of the welding current, the welding voltage and the welding traveling speed of each wire can be matched with the welding heat input value required by the test;

during welding, the forward inclination angle of the front wire welding gun along the welding direction is delta₁The backward inclination angle of the medium wire welding gun is delta from 5 degrees to 25 degrees₂0-10 DEG backward inclination angle delta of the rear wire welding gun₃10-30 degrees; forming an included angle theta between the front wire welding gun and the straight side of the groove by 5-20 degrees along the width direction of the groove, wherein the middle wire welding gun and the rear wire welding gun are both vertically arranged; the distance L between each wire end and the straight side of the groove is equal to E/1.5+2.0, the unit of L is mm, and E is welding heat input;

and step five, obtaining a welding joint after welding, observing and detecting the crack tendency of the welding joint to evaluate the technological weldability of the material, and evaluating the service weldability of the material through the mechanical property detection of the welding joint.

In the welding process parameters of the fourth step: the welding current of the front wire is 650-1500A, and the welding voltage is 30-40V; the welding current of the middle wire is 600-1200A, and the welding voltage is 33-42V; the welding current of the rear wire is 450-1000A, and the welding voltage is 35-44V; the welding walking speed of each welding wire is 700-1200 mm/min, and the distance between the welding wires is 20-40 mm.

And in the fifth step, the mechanical property detection comprises the detection of low-temperature impact and fracture toughness of a coarse crystal area of a welding heat affected zone adjacent to the single-side straight-edge fusion line.

The invention relates to a low-carbon microalloy steel high heat input weldability assessment method based on multi-wire submerged arc welding, which is realized according to the forming characteristics of a welding pool and a welding seam under the condition that the high heat input is 5.0-10.0 kJ/mm and the technical characteristics that the multi-wire submerged arc welding has good adaptability and welding seam forming quality in the heat input range. Secondly, by designing a special welding joint groove form with a single-side straight edge, constructing and optimizing scientific and reasonable welding process parameter combinations (including welding current, welding voltage, welding walking speed and welding wire spacing) and welding gun position setting, and controlling the quality of a welding process, particularly a weld line straightness control technology, the welding joint with the single-side weld line with good straightness can be obtained. By observing and detecting the crack tendency of the welded joint, the process weldability of the material can be evaluated. Through the mechanical property detection of a welding joint, particularly the low-temperature impact and fracture toughness detection of a coarse grain zone (CGHAZ) of a welding heat affected zone adjacent to a single-side straight-edge fusion line, and the straightness of the single-side straight-edge fusion line can ensure that 80% of impact toughness sampling notch grooves are positioned in the CGHAZ, the use weldability of the material under the condition of high heat input can be evaluated. The method can be used for evaluating the weldability and the use weldability of the process at the same time, and has high universality and representativeness in consideration of the practical situation of the field production and high-efficiency welding of the low-carbon micro-alloy steel thick plate products and structures in the important industrial field and the adaptability of multi-wire submerged arc welding to a high heat input range. Meanwhile, the characteristic of the single-side straight-edge fusion line ensures that the tested position is accurately positioned at the theoretically weakest CGHAZ of the welding joint in the sampling process of impact toughness and fracture toughness. The method has important and direct guiding significance and practical value for weldability evaluation of the low-carbon micro-alloy steel thick plate in different fields in field welding construction under the condition of high heat input.

Compared with the prior art, the invention has the following beneficial effects: the method has universal applicability, can simultaneously meet the evaluation requirements of process weldability and use weldability under the condition of high heat input, and has the advantages of convenient implementation, flexible operation, low requirement on hardware equipment, low implementation cost and good reproducibility.

Drawings

FIG. 1 is a schematic structural diagram of a welding joint groove form of the low-carbon micro-alloy steel high-heat input weldability evaluation method based on multi-wire submerged arc welding of the invention;

FIG. 2 is a schematic view of the angle of inclination of each wire bonding gun of the present invention in the welding direction;

FIG. 3 is a schematic diagram of the angle of inclination of the lead wire torch of the present invention in the direction along the width of the bevel;

FIG. 4 is a schematic diagram of the inclination angle of the medium wire welding gun of the present invention in the direction along the width of the groove;

FIG. 5 is a schematic diagram of a specific weld joint groove form employed by an embodiment of the present invention.

In the figure, 1 test plate, 2 backing plate, 3 front wire welding gun, 4 middle wire welding gun and 5 rear wire welding gun.

Detailed Description

The invention is further described with reference to the following figures and specific examples.

Referring to fig. 1-4, a low-carbon micro-alloy steel high-heat input weldability evaluation method based on multi-wire submerged arc welding mainly aims at the occasion of a high welding heat input range of 5.0-10.0 kJ/mm involved in the manufacturing process of products and structures in the important industrial field, applies a low-carbon micro-alloy steel submerged arc welding wire with the diameter of 4.0-6.0 mm and a common sintered flux, combines the characteristics of a welding arc and a molten pool under the high-heat input condition, constructs and optimizes a welding process parameter combination, a welding gun position setting and welding process quality control through a specially designed groove form of a single-side straight-edge welding joint adapting to the welding condition, particularly a weld line straight-edge control technology and the like, and obtains a welding joint with good quality and no defect, and comprises the following steps:

step one, selecting a test plate 1 as a low-carbon microalloy steel plate, wherein the thickness t of the steel plate is more than or equal to 40 mm.

And step two, selecting a low-carbon micro-alloy submerged arc welding wire and a common alkaline sintered flux for matching use, wherein the diameter of the welding wire is 4.0-6.0 mm.

Step three, referring to fig. 1, butt welding is performed on the flat welding positions of the pair of test plates 1, grooves of the pair of test plates 1 are in the form of blunt-edged double-V-shaped grooves with straight edges on one side, the blunt edges are deflected outwards to form lower V-shaped grooves, the lower V-shaped grooves are deflected outwards to form upper V-shaped grooves, the lower V-shaped grooves form an angle α with the central axis of the grooves, the upper V-shaped grooves form an angle β with the central axis of the grooves, and homogeneous backing plates 2 are arranged on the back surfaces of the grooves, wherein α is 40-65 °, β is 25-45 °, the height a of the blunt edges is 5-11 mm, the height b of the lower V-shaped grooves is 11-25 mm, b is 1/3 smaller than the thickness t of the steel plate, the thickness c of the backing plates 2 is 12-25 mm, the width d of the backing plates 2 covering the grooves is 80-400 mm, and the pairing gap of the test plates 1 is 0-1 mm. By adopting the welding joint groove form with the optimized design, the design requirement of a straight edge on a single side is ensured, and meanwhile, the auxiliary forming root welding method of adding the homogeneous base plate 2 on the back surface of the groove is adopted, so that the requirement on the size and the thickness of the base plate 2 is moderate, the root welding is ensured not to burn through, and the operation difficulty cannot be increased due to the over-thickness of the base plate 2. The truncated edge has larger size, and can fully utilize the advantage of strong penetration capability of multi-wire submerged arc welding. The opening width of the groove can meet the setting requirement of a welding gun optimized according to the requirement, so that the straight edge of one side is fully melted through, and meanwhile, the opening width of the groove is not too wide, so that the welding efficiency is reduced.

And step four, welding the test plate 1 by adopting a multi-wire automatic submerged arc welding mode, wherein the multi-wire comprises a front wire, a middle wire and a rear wire, and the multi-wire is simultaneously welded in a eutectic pool.

According to the requirements of multi-wire submerged arc welding in a welding heat input range of 5.0-10.0 kJ/mm, and the characteristics of large penetration depth and strong fusion capability of the edge of a groove of the multi-wire submerged arc welding, used welding process parameters are constructed and optimized, and the parameters comprise:

when the welding heat input E is 5.0-10.0 kJ/mm, the welding current I of the front wire_{Front side}And the diameter R of the front filament_{Front side}Has a relationship of_{Front side}＝(150～250)R_{Front side}(ii) a Welding current I of medium wire_InAnd the diameter R of the medium thread_InHas a relationship of_In＝(140～200)R_In(ii) a Welding current I of rear wire_{Rear end}And rear filament diameter R_{Rear end}Has a relationship of_{Rear end}＝(110～180)R_{Rear end}(ii) a The welding voltage of each wire is respectively matched with the welding current and the dry elongation of the welding wire, and the combination of the welding current, the welding voltage and the welding traveling speed of each wire can be matched with the welding heat input value required by the test.

Current filament diameter R_{Front side}Middle filament diameter R_InAnd rear filament diameter R_{Rear end}When the thickness is 4.0-6.0 mm, the welding current of the front wire is 650-1500A, and the welding voltage is 30-40V; the welding current of the middle wire is 600-1200A, and the welding voltage is 33-42V; the welding current of the rear wire is 450-1000A, and the welding voltage is 35-44V. The welding walking speed of each welding wire is 700-1200 mm/min, and the distance between the welding wires is 20-40 mm. In the welding process, according to actual needs, the front wire, the middle wire and the rear wire can be selected to have the same diameter, and welding wires with different diameters can also be combined.

Referring to fig. 2, in the multi-wire submerged arc welding process, since the front wire mainly contributes to the penetration depth, in order to ensure sufficient penetration of the large-sized truncated edge, the front wire welding torch 3 is set to be inclined forward in the welding direction by an angle δ₁Because the back wire mainly plays the effect of filling the groove, back wire welding torch 5 sets up to incline angle δ backward along the welding direction for 5 ~ 25-₃10 ~ 30, owing to the effect of well silk is the molten bath ability that increases, both need promote the penetration depth, need guarantee the abundant filling of groove again, well silk welder 4 sets up to be the angle of inclination delta along welding direction backward₂＝0～10°。

Referring to fig. 3 and 4, in view of the sensitivity of the straight-side unfused defect in the form of a single-side straight-side groove, the front wire welding gun 3 forms an included angle θ of 5 to 20 ° with the straight-side of the groove in the width direction of the groove, while under the condition of high heat input, the multi-wire submerged arc welding molten pool has a large size and a strong fusion capability to the edge of the groove, the included angle between the front wire welding gun 3 and the straight-side of the groove is not too large, otherwise, the straightness of the fusion line after welding is damaged, and in addition, the multi-wire molten pool is shared during welding, so that the middle wire welding gun 4 and the rear wire welding gun 5 are both vertically arranged, and the middle wire welding gun 4 and the rear wire welding gun 5 do not need to be inclined and the fusion of the straight-side is not affected.

In addition, considering the change of the size of a molten pool and the influence of the change on the fusion behavior of the edge of the groove when different welding heat inputs are input, when the welding heat input E is changed within the range of 5.0-10.0 kJ/mm, the distance L between the end of each wire and the straight side of the groove meets the relation: l ═ E/1.5+2.0, L in mm and E in kJ/mm. Within a certain welding heat input range, when the distance between the end of the welding wire and the straight side of the groove is proper, the fusion of the straight side is good, the straightness of a fusion line on the straight side after welding cannot be damaged, a welding joint with good quality and no defect can be obtained, and the straightness of the fusion line on the straight side of the single side can ensure that 80 percent of the welding wire is positioned in the CGHAZ when impact toughness sampling grooving is carried out.

And fifthly, obtaining a welding joint after welding, observing and detecting the crack tendency of the welding joint to evaluate the technological weldability of the material, and evaluating the use weldability of the material by detecting the mechanical properties of the welding joint, particularly detecting the low-temperature impact and the fracture toughness of a coarse crystal area of a welding heat affected area adjacent to a single-side straight-edge fusion line.

Examples

Referring to fig. 5, a typical EH36 ship-building steel with a thickness t of 50mm is selected as a test plate 1, a homogeneous backing plate 2 is added to the back of a groove to assist in forming a root welding method, and a weldability evaluation test is performed based on multi-wire submerged arc welding with a welding heat input in a range of 5.0-10.0 kJ/mm, wherein the specific welding joint form is as follows: alpha is 50 degrees, beta is 35 degrees, a is 5-11 mm, b is 15mm, c is 16mm, and d is 100 mm. The wire used was AWS F9a4-EG flux matched, and the wire diameter was 5.0 mm.

Table 1 lists specific welding process parameter combinations for examples 1-6, as follows:

table 2 lists the specific weld gun position settings, the distance L between each wire end and the straight edge side of the groove, the corresponding heat input values, and the obtained weld quality evaluation results of examples 1-6, as follows:

as can be seen from tables 1 and 2, all the examples have stable welding process and good welding quality, and can be used for the weldability evaluation of typical low-carbon micro-alloy steel thick plates with the characteristic of a single-side straight-edge weld line, wherein the welding heat input range of the typical low-carbon micro-alloy steel thick plates is 5.0-10.0 kJ/mm. The welding quality mainly comprises the appearance forming quality and the interior forming quality of a welding seam, and the judgment standard is as follows, ANSI/AWS D1.1: and (5) welding specification of a steel structure.

The method for evaluating the high-heat-input weldability of the low-carbon micro-alloy steel based on the multi-wire submerged-arc welding has the advantages that the process weldability of materials in the welding process and the using weldability of the materials after welding are taken into consideration, the universality and the universality are realized in the weldability evaluation of the low-carbon micro-alloy steel thick plates used in different industries and fields within the given high-welding heat input range, and the important application value is realized in the rapid and accurate evaluation of the weldability with high safety requirements in the industrial application of the low-carbon micro-alloy steel thick plates.

The present invention is not limited to the above embodiments, and any modifications, equivalent replacements, improvements, etc. within the spirit and principle of the present invention should be included in the protection scope of the present invention.