Two common welding defects and causes

Two common welding defects and causes shared by welding turntable manufacturer.

Welding is a key work in the construction of large-scale installation engineering. The quality and efficiency of welding directly affect the safety operation and manufacturing time limit. Due to the different level of technical workers, the welding process is intermingled, easy to have many defects; To reduce or prevent the generation of welding defects and improve the quality of the completion of the project.

1. The size of welding seam is not up to the requirements, which is mainly manifested as coarse welding wave, uneven shape, excessively low or high welding seam strengthening height, uneven welding wave width and unilateral or excessive fillet weld subsidence, etc. The reasons are as follows: 1. Improper welding groove Angle or uneven assembly gap; 2. Welding current is too large or too small, improper selection of welding specifications; 3. Uneven speed and improper welding rod (or handle) Angle.

FIT Fit Up Station

2. The crack, mainly manifested as sharp shape at the end of the crack, serious stress concentration, great impact on bearing alternating and impact load, static tension, is the most dangerous defect in the weld. It can be divided into cold crack, hot crack and reheat crack. (cold crack) refers to the crack under 200℃, which has a close relationship with hydrogen, the main reasons are: 1. 2. Improper selection of welding materials; 3. The welding joint is too rigid and the process is unreasonable; 4. Brittle and hard structure occurs in and around the welding seam; 5. Improper selection of welding specifications. (thermal crack) refers to the crack (mainly solidification crack) which is generated at more than 300℃. The main reasons are as follows: 1. Welding of pure austenitic steel, some high nickel alloy steel and nonferrous metal occurs easily. 2. There are more harmful impurities such as sulfur in the welding seam. 3. Improper selection of welding conditions and joint forms. Reheat crack means stress relief annealing crack. Refers to the intergranular crack in the heat-affected zone caused by post-welding heat treatment or high temperature in the high-strength welding area. The main causes are: 1. Improper heat treatment condition of stress relieving annealing. 2. Influence of alloy composition. Elements such as chromium, molybdenum, vanadium and boron have the tendency to increase the reheat crack. 3. Improper selection of welding materials and welding specifications. 4. Unreasonable structural design causes large stress concentration.

We supply welding rotator design service, self-adjusting welding rotator, etc., welcome to purchase our products.