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Weld shape design method capable of ensuring undermatching butt joint to bear load in light of strength of parent materials

A technology of butt joint and design method, which is applied in welding equipment, arc welding equipment, metal processing equipment, etc., can solve the problems of unequal, inequivalent, and low-matching butt joints with low bearing capacity compared with the base metal.

Inactive Publication Date: 2011-06-01
HARBIN INST OF TECH
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0007] The purpose of the present invention is to provide a weld shape design method that can make low-matching butt joints bear the load according to the strength of the base metal, so as to solve the problem that the bearing capacity of low-matching butt joints is lower than that of matching joints above equal strength (that is, the bearing capacity of low-matching butt joints is lower than that of matching joints above equal strength The bearing capacity of the base metal is not equal or not equivalent)

Method used

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  • Weld shape design method capable of ensuring undermatching butt joint to bear load in light of strength of parent materials
  • Weld shape design method capable of ensuring undermatching butt joint to bear load in light of strength of parent materials
  • Weld shape design method capable of ensuring undermatching butt joint to bear load in light of strength of parent materials

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specific Embodiment approach 1

[0072] Specific implementation mode one: see figure 1 The weld shape design method described in this embodiment that can make the low-matching butt joint bear the strength of the base metal is based on the fact that the stress concentration factor of the weld root is equal to the matching ratio of the yield strength of the low-matching joint, and the stress concentration factor of the weld toe is reduced as much as possible. "Equal load"; according to the bearing characteristics, when the fatigue strength requirement of the butt joint is not very high, the shape of the weld seam of the butt joint is determined as figure 1 The shown weld shape adopts a simple circular arc curve transition between the reinforcement and the base metal; the design method of the weld shape is:

[0073] Step 1. Calculate the yield strength matching ratio μ of low-matching joints MMR (The ratio of the yield strength of the weld deposited metal to the yield strength of the base metal): design a plate...

specific Embodiment approach 2

[0098] Specific implementation mode two: see figure 2 and image 3 The weld shape design method described in this embodiment that can make the low-matching butt joint bear the load according to the strength of the base metal is based on the fact that the stress concentration factor of the weld root is equal to the matching ratio of the yield strength of the low-matching joint, and the stress concentration factor of the weld toe is minimized. "Equal load"; according to the bearing characteristics, when the fatigue performance of the butt joint is very high, the shape of the weld seam of the butt joint is determined as: figure 2 The transition curve shown between the reinforcement and the base metal includes two parts: a 45° broken line and an arc curve; the weld shape design method is as follows:

[0099] Step 1. Calculate the yield strength matching ratio μ of low-matching joints MMR (The ratio of the yield strength of the weld deposited metal to the yield strength of the ...

Embodiment

[0131] Example (combined Figures 1 to 4 ):

[0132] 1. Design the plate-shaped tensile specimen, test the tensile properties of the base metal and the weld metal, and take the average value of the three specimens to obtain the yield strength matching ratio of the joint.

[0133] 2. According to the bearing characteristics, select the ideal or non-idealized weld shape scheme; according to the matching ratio of the plate thickness and the yield strength of the joint, according to the design steps of the specific embodiment 1 or the specific embodiment 2, determine the low matching "equivalent bearing" "Weld geometry parameter values ​​for butt joints.

[0134] 3. Welding low matching butt joints, the welding sequence is as follows Figure 4 shown.

[0135] 4. Machining to obtain the weld shape of the "equal load" butt joint and its joint geometric parameter values. In the case of ensuring the designed height, the upper surface of the excess height may not be polished. For ...

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Abstract

The invention relates to a weld shape design method capable of ensuring undermatching butt joint to bear load in light of strength of parent materials, solving the problem that the bearing capacity of the undermatching butt joint is lower than that of the overmatching weld joint. The method comprises the following main steps: computing the yield strength matching ratio muMMR of the undermatching joint, determining a weld shape scheme with minimum stress concentration, establishing a relation equation between the geometric parameters of a plate butt joint and the coefficients of stress concentration at weld toes and weld roots, computing the height h of weld reinforcement, the radius r of the weld toes and the total half width of cover passes and obtaining required weld geometric parametervalues. The method can ensure that the high-strength steel or ultra high-strength steel welding structure bearing tensile load can not only adopt undermatching joint mode which obviously reduces the occurrence rate of cold cracks but also ensure the static load bearing capacity of the undermatching butt joint not to be lower than that of the high-strength parent material and the fatigue strength to be obviously higher than the as-welded equalmatching joint. The method is suitable for X-shaped groove double-welded undermatching plate butt joints.

Description

technical field [0001] The invention relates to a welding seam shape design method, in particular to a welding seam shape design method which can make low-matching butt joints bear the strength of the base metal. Background technique [0002] With the wide application of high-strength steel in ships, submarines, pressure vessels, pressure pipelines, bridges, especially low-temperature vessels and cold marine structures, the problems of welding cracks, heat-affected zone embrittlement and softening of high-strength steel have become prominent. Among them, the damage caused by cold crack defects is the most serious, and it has become one of the main reasons for the early failure of welded structures. At the same time, the performance requirements of high-strength steel welded structures have been continuously increased due to harsh service conditions, and it is difficult to completely solve these problems by adjusting the chemical composition of steel. [0003] At present, th...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): B23K9/02
Inventor 方洪渊赵智力杨建国刘雪松
Owner HARBIN INST OF TECH
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