Precision bright tube2

2 year ago

57 0

Shandong Jianlong Steel Co.

 3 year year

Product details

Product Description:

The precision bright tube is quenched to obtain martensite structure, and then tempered at 450~600 ℃; Or after tempering at 650 ℃, it passes through 350~600 ℃ at a slow cooling rate; Or after tempering at 650 ℃ and heating for a long time at 350~650 ℃, the precision bright tube will be embrittled. If the embrittled 20 # precision steel tube is reheated to 650 ℃ and then quickly cooled, the toughness can be restored, so it is also called% 26ldquo; Reversible tempering brittleness% 26rdquo; The high temperature tempering brittleness is shown by the increase of the transition temperature from toughness to brittleness of precision bright tubes. High temperature tempering brittleness. The sensitivity is generally expressed by the difference between the ductile brittle transition temperature (% 26Delta; T) of the ductile state and the brittle state. The higher the brittleness of high temperature tempering, the higher the proportion of intergranular fracture on the fracture surface of precision bright tube.

The role of elements in precision bright tubes on high temperature tempering brittleness can be divided into: (1) Impurities such as phosphorus, tin, antimony, etc. that cause high temperature tempering brittleness of precision bright tubes. (2) Alloying elements that promote or slow down high temperature tempering brittleness in different forms and degrees. Chromium, manganese, nickel and silicon play a promoting role, while molybdenum, tungsten and titanium play a delaying role. Carbon also plays a catalytic role. General carbon precision bright tube is not brittle to high temperature tempering. It is sensitive. Binary or multicomponent alloy steels containing chromium, manganese, nickel and silicon are very sensitive, and their sensitivity depends on the type and content of alloy elements.

The sensitivity of the original structure of the tempered precision bright tube to the high temperature tempering brittleness of the steel is significantly different. The martensite high temperature tempering structure is most sensitive to high temperature tempering brittleness, followed by bainite high temperature tempering structure and pearlite structure.

The essence of high temperature tempering brittleness of precision bright tubes is generally believed to be the result of segregation of phosphorus, tin, antimony, arsenic and other impurities at the grain boundary of the original austenite, resulting in grain boundary embrittlement. However, alloy elements such as manganese, nickel, chromium and the above impurities are co segregated at the grain boundary, which promotes the enrichment of impurities and intensifies the embrittlement. On the contrary, molybdenum has a strong interaction with impurities such as phosphorus, which can produce precipitation phase in the crystal and hinder the segregation of phosphorus at the grain boundary, and can reduce the high-temperature tempering brittleness of rare earth elements, which also has a similar role to molybdenum. Titanium can effectively promote the precipitation of phosphorus and other impurities in the crystal, thus reducing the grain boundary segregation of impurities and slowing down the high temperature tempering brittleness.

The measures to reduce the high temperature tempering brittleness of precision bright tubes are as follows: (1) oil cooling or water rapid cooling after high temperature tempering to inhibit the segregation of impurity elements at grain boundaries; (2) The precision bright tube containing molybdenum is adopted. When the molybdenum content in the steel increases to 0.7%, the high temperature tempering embrittlement tendency is greatly reduced. Beyond this limit, special carbides rich in molybdenum are formed in 20 # precision steel tube, the molybdenum content in the matrix is reduced, and the embrittlement tendency of precision bright tube is increased instead; (3) Reduce the content of impurity elements in 20 # precision steel pipe; (4) For parts that have been working in the high-temperature tempering embrittlement zone for a long time, it is difficult to prevent embrittlement by adding molybdenum alone. Only by reducing the content of impurity elements in 20 # precision steel pipe, improving the purity of precision bright pipe, and supplemented by composite alloying of aluminum and rare earth elements, can the high-temperature tempering embrittlement be effectively prevented.

Shandong Jianlong Iron and Steel Co., Ltd. is a company with more than 10 years of experience. We are located in Liaocheng, one of the largest steel producing areas in China. We have our own production plant. We also deal in prepainted steel coil, corrugated roofing sheet , etc. Welcome to purchase.

Product Specification:

Name	Precision Bright Seamless Steel Pipe
Outer Diameter	30-250mm
Wall Thickness	2-30mm
Material Grade	20# 45# Q345B Q345D 25Mn 27SiMn E355
Certificate	ISO9001 2008
Standard	GB/T8713,GB/T3639,DIN2391,EN10305,ASTMA519
Technique	ASTM, ASME, A/SA 192, 209, 210 and 213 specifications and all associated grades. EN 10216, DN 17175,BS 3059, JIS 3461 – 3462
Package	1. bundle packing 2. marking as per customer's requests 3. paint on the pipe as per customer request 4. pipe caps as customer request
Application	Widely used in hydraylic and pneumatic cylinder for automobile, engineering machinery, textile machinery, etc.
Delivery Condition	BK/BKW/BKS/GBK/NBK
Delivery Time	Within 20-30 days after receiving downpayment or as client’s request
Trade Terms	FOB Yantai, Qingdao, or as client’s request