Steel structure with light weight, short construction period, adaptable, attractive appearance, easy maintenance, etc., its application more widely. The development of steel and steel production are closely related. China has become the world's steel-producing countries in 2005, Chinese steel production has exceeded 300 million tons, of which up to 140 million steel production, energy, transportation, metallurgy, machinery, chemical, electrical, building and infrastructure construction and other fields of steel structure construction industry has become the backbone of the national economy.
Welded steel construction features and difficulties
Looking at the current status of China's steel structure engineering and development trend, more and more with the modern architectural style and construction of high-tech features, its main features are:
A novel and unique shape, structure, system range, the node structure is complicated, multi-form welded joints, component production and field installation in Carbon Steel Electrode technology more and more difficult. For example: the National Stadium "Bird's Nest," a large number of steel works complex truss columns, the main truss, the second node structure welding, weld criss-cross, the construction is very difficult.
2 building height is high, large span structures, seismic performance of welded steel design of the main quality requirements are high. Such as: frame beam-column connection weld, shear plate welds and column connections, beam web and column connections and column splice weld seam, are the main parts of the structure are basically the slope population penetration level welds, 100% ultrasonic testing, very high quality requirements for welding.
3 varieties of steel specifications using more and more and more tend to use high-strength low-alloy structural steel and large thickness of the steel, iron and steel production process with increasing levels of, steel, austenitic stainless steel sheet has also been increasingly more applications. Therefore, the required on-site pre-construction, the steel used for the delivery status, to live a new steel Welding Electrode Manufacturers test, explore the science of welding parameters, welding process to develop appropriate measures.
4 factory production and site installation linked by many factors, many different types of cross-operation, on-site installation difficult.
Chrome-nickel Stainless Steel Electrode has good corrosion resistance and oxidation resistance, widely used in chemical, fertilizer, petroleum, medical machinery manufacturing. Chrome-nickel stainless steel welded by repeated heating of carbide precipitation and reduce the corrosion resistance and mechanical properties.
Drug skin of chrome-nickel stainless steel with titanium calcium type and low hydrogen type. Titanium calcium type can be used for AC-DC, AC welding penetration is shallow, and easy to redness, so as far as possible with DC power supply. Diameter of 4.0 and below can be used for all position welding of 5.0 and above for flat butt and fillet weld.
Electrodes use should be kept dry, lime-titania type should be dry 1 hour at 150 ℃, low hydrogen type should be dried for one hour (not be repeated drying by 200-250 ° C, otherwise the drug leather easy to crack and peel off), to prevent the electrode drug skin viscous oil and other dirt, so as to avoid causing the weld to increase the carbon content and impact of weldment quality.
In order to prevent corrosion between the eyes, the welding current is not too large, about 20 percent less than the Carbon Steel Electrode , the arc should not be too long, rapid cooling layer is appropriate to narrow the weld heating.