The six major defects of welding, their causes, hazards and preventive measures are all hereTime of issue : 2021- 11-05
1、 Appearance defect appearance defect (surface defect) refers to the defect that can be found from the workpiece surface without the help of instruments. The common appearance defects include undercut, weld bead, depression and welding deformation. Sometimes there are surface pores and surface cracks, and the root of single-sided welding is not fully welded.
It refers to the depression or groove formed in the base metal part along the weld toe. It is the gap left by the lack of sufficient supplement of deposited metal after the arc melts the base metal at the weld edge.
The main causes of undercut are that the arc heat is too high, that is, the current is too large, the strip conveying speed is too small, the angle between electrode and workpiece is incorrect, the swing is unreasonable, the arc is too long, and the welding sequence is unreasonable. The magnetic bias blow of arc in DC welding is also a cause of undercut. Some welding positions (vertical, horizontal and vertical) will aggravate undercut, which reduces the effective cross-sectional area of base metal and the bearing capacity of the structure. At the same time, it will also cause stress concentration and develop into crack source.
Prevention of undercut: correcting the operation posture, selecting reasonable specifications and adopting good strip transportation methods will help to eliminate undercut. When welding fillet weld, AC welding instead of DC welding can also effectively prevent undercut.
B. Weld bead
The liquid metal in the weld flows to the base metal that is not melted due to insufficient heating or overflows from the root of the weld. The metal tumor formed after cooling that is not fused with the base metal is the weld bead. Too strong welding specification, too fast melting of welding rod, poor quality of welding rod (such as eccentric core), unstable characteristics of welding power supply and improper operation posture are easy to cause weld beading, which is easier to form weld beading in horizontal, vertical and overhead positions.
Weld beading is often accompanied by incomplete fusion and slag inclusion defects, which is easy to lead to cracks. At the same time, the weld bead changes the actual size of the weld and will bring stress concentration. The weld bead inside the pipe reduces its inner diameter and may cause blockage of flow animals.
Measures to prevent weld beading: make the weld in the flat welding position, correctly select the specification, select the non eccentric core electrode and operate reasonably.
Environmental corrosion of steel materialsTime of issue : 2020- 05-07
This paper introduces the current status of the development of environmental corrosion test technology for steel materials at home and abroad, summarizes various test methods required in the research and development of new corrosion-resistant steel materials, and analyzes outdoor exposure tests, indoor simulated accelerated tests, online corrosion monitoring and large-scale testing.
Chongqing Dayou Surface Technology Co., Ltd. participated in the 2019 Western China International Sourcing FairTime of issue : 2020- 04-17
The Western Cross-Procurement Conference is one of the three major exhibitions sponsored by the Shaanxi Provincial People's Government. It has been held for seven consecutive sessions. A total of more than 1,900 internationally renowned large-scale purchasers and Fortune 500 companies participated in 80 countries and regions. It has become a new platform for Shaanxi to open up, cooperate and serve the "Belt and Road" construction.
Research Progress on Corrosion Performance of High Entropy Alloy CoatingTime of issue : 2020- 03-18
The research on the corrosion resistance of high-entropy alloy coatings in recent years is summarized, mainly from the preparation process, alloy composition and process parameters on the corrosion resistance of high-entropy alloys, and the existence of corrosion-resistant high-entropy alloy coatings Suggestions on the issues and research priorities.
The six major defects of welding, their causes, hazards and preventive measures are all hereTime of issue : 2020- 03-17
1. Appearance defects Appearance defects (surface defects) refer to defects that can be found from the surface of the workpiece without the aid of instruments. Common appearance defects include undercuts, weld bumps, depressions, and welding deformations, and sometimes surface pores and surface cracks, and the roots of single-sided welding are not fully welded.
Hand in hand, thank you for having you-2017 Chinese New Year Annual MeetingTime of issue : 2017- 02-08
The new year is full of new goals and pursuits. The hopeful 2017 has come to us in great strides. Looking back on the 2016 just past, there are struggles, persistence, joy, gains, and every hard-working you.
Chongqing Dayou Surface Technology Co., Ltd. 2017 Annual Science and Technology Work Conference was successfully heldTime of issue : 2017- 02-28
At 10 o'clock in the morning on February 18, 2017, Chongqing Dayou Surface Technology Co., Ltd.'s 2017 Science and Technology Work Conference was held in the company's conference hall. Company leaders, heads of various departments and all colleagues in the technical department attended the meeting.
The anti-corrosion technology of zinc-nickel infiltration layer appeared in the 14th China International Modern Railway Technology and Equipment Exhibition in ShanghaiTime of issue : 2017- 11-13
From October 26, 2017 to October 29, 2017, the 14th China International Modern Railway Technology and Equipment Exhibition hosted by the China Academy of Railway Sciences and China World Trade Center Co., Ltd. opened at the Shanghai Exhibition Center. More than 240 companies and units from three countries and regions participated in the exhibition. This exhibition will hold exhibitions around the themes of "intelligent railway" and "new railway technology", drawing a blueprint for the development of railways for the "Belt and Road".
Chongqing Rongchang District Dayou Surface Technology Co., Ltd. Publicize the environmental protection acceptance report of the completion of the construction project of the infiltration material and anticorrosion treatment processing service industrializaTime of issue : 2018- 05-18
On May 15, 2018, Chongqing Rongchang Dayou Surface Technology Co., Ltd. organized relevant units and experts to convene the construction project of the expansion project of the infiltration layer material and anticorrosive treatment processing service industrialization model base of Chongqing Rongchang Dayou Surface Technology Co., Ltd. Completion of the environmental protection acceptance meeting, participating units include Chongqing Rongchang District Environmental Protection Bureau
Research and Application of New Type Metal Anticorrosive Coating Preparation TechnologyTime of issue : 2016- 06-21
HC Surface Treatment Network News: As the energy crisis becomes more and more prominent, the development and utilization of rich marine resources has been paid more and more attention. The ability to develop marine resources not only reflects the level of a country's marine technological innovation and its promotion and application, but also reflects the country's competitive potential and comprehensive national strength in the marine field. At present, my country's exploration and development in the marine field is continuously heating up, and more and more marine engineering facilities are put into