Overview of cast iron

Iron carbon alloys with a carbon content greater than 2.1% in cast iron series are widely used in various modern industrial fields due to their abundant resources, low cost, good castability, machinability, wear resistance, and seismic resistance. Cast iron is divided into gray cast iron (including nodular cast iron and vermicular cast iron) and white cast iron according to the form of carbon in steel.

Note: In addition, there is a type of cast iron between white cast iron and gray cast iron, which is caused by improper structural composition and fast cooling rate. Due to the difficulty in processing and poor performance of the cast iron, this article will not introduce it in detail.

Characteristics and Weldability of Cast Iron

1. Rich in resources, low in cost, widely used in modern machine manufacturing industry;

2. Good castability, machinability, wear resistance, and seismic resistance;

3. Compared with steel, it has extremely poor weldability, low strength, poor plasticity, and is prone to defects such as white spots, cracks, and pores;

4. There are three main requirements for cast iron welding:

• ① Repair of castings with performance defects;
• ② Repair of damaged castings during use;
• ③ Production and maintenance of parts.

Among them, carbon (C) in gray cast iron is distributed in a flake shape and has relatively good weldability, making it the main welding repair object. Welding rod arc welding is the most commonly used welding method for repairing castings such as machine tools, agricultural machinery, automobiles, and molds.

Cast iron can be repaired by welding when encountering casting defects and cracks during use. Since the 1970s, cast iron welding technology has been widely used, and welding materials have also formed a series of products.

For example, various large and medium-sized motors, gearbox shells and foundation cracks, pump shell cracks, diesel engine and air compressor shell cracks, frame and guide rails, cast iron molds, cast iron gears, cast iron hydraulic cylinders, etc.

Including various molds widely used in industrial production, such as forging molds, stamping molds, metal extrusion molds, glass molds, etc., overlay welding repair processes are also frequently used.

The repair process not only extends the mission of existing tools, but also reduces the cost of repairing and replacing molds, bringing huge comprehensive benefits. Whether it is reducing production costs, improving product utilization through multiple repairs, or facilitating the control of workpiece structure and shape, all are the most convenient and economical methods.

Brief comparison between conventional welding and repair welding

Comparison project	Conventional welding	Repair welding
Welding objects	Ordinary carbon steel, low alloy steel	Cast iron, medium to high carbon steel
Weldability	Good weldability, simple process, and easy construction	Poor weldability, complex process, and high construction difficulty
Restraint and welding stress	Less	Large
As-welded	After annealing	High-temperature soldering
Post heat treatment	Having mature heat treatment conditions and processes	Almost impossible for post heat treatment

 

Qingdao Jiahao Kairui Electromechanical Engineering Co., Ltd. was established in 2007. It is a high-tech enterprise dedicated to the integration of robot application systems, the design and development of intelligent high-end equipment welding machines, and flexible tooling. Its business covers industries such as locomotive manufacturing, automotive manufacturing, engineering machinery, petroleum equipment, power products, and pressure vessels, providing users with the best automation solutions. The company has established a technical department, sales department The administrative and financial department has an office and storage area of 1600 square meters.

Agent sales: ABB robots, Funis aluminum welding machines, Sairong laser tracking, Haibao plasma cutting machines, Safu aluminum welding wires, Jinglei welding materials, Lincoln welding materials, SMC nickel based welding materials, Aerospace Kaitian environmental protection equipment, 3M protective equipment, various welding and cutting vulnerable parts, etc.