At the same time， the heating temperature and heating time will also have a great impact on the performance of square tube. The heating of square tube blank is the key process to ensure that the square tube blank has enough plasticity and complete the smooth perforation. If the heating temperature is too high or the heating time is too long， the billet of the square tube will be burned and decarburized， and even the chemical composition of the square tube will be unqualified (unqualified carbon content)， which is easy to cause batch quality problems and seriously affect the product qualification rate.
9According to production， square tubes are divided into hot-rolled tubes，Seamless square tube cold-rolled tubes，32 hot dip galvanized pipeIn which industries will the application be more smooth cold drawn tubes， tubes， pipe jacking， etc. According to the section shape the square tube is divided into round and special-shaped. The special-shaped tube has many complex shapes， such as square， oval， angular， angular melon seed， star and winged tube.
vImprove the positioning and pre bending steps，Seamless square tube if necessary， to ensure that the web hunting problem does not occur when pressing parts. Change the shape of the surface pressure of the material to ensure the quality of the parts and avoid the non movement of the surface shape of the roll gap， resulting in uneven walking feeding.
Common specifications of square tube: ~ & times; × .～ × × .～ × × .～ × × .～ × × ～ × × ～ × × ～ × × ～ × × ～ × × ～ × × ～ × × ～ × × ～ × × ～ × × ～ × × ～ × × ～ × × ～ × × ～ × × ～ × × ～
KAnnette SharonFirst， remove the deposits on the surface of the square pipe surface with copper wire brush. Use the perfume oil or other scrubbing oil on the surface layer， or use phosphate or chromate solution， brush， spray or dip coating. After the fixed reaction time， rinse the acid solution with plenty of fresh water on the surface.
OaMechanical polishing: after processing， short gloss， dull and rusty. Suitable for processing simple parts，Seamless square tube medium and small products.
Both internal and external welding of square pipes are carried out by American Lincoln Electric welding machine for single wire or double wire submerged arc welding， so as to obtain stable welding specifications.
All seamless qb square tubes shall be tested for mechanical properties. Mechanical property tests are mainly divided into two categories: tensile test and hardness test.
lAt this time，32 hot dip galvanized pipeIn which industries will the application be more smooth if the welding wire of the same material is used for spot welding where the thickness is insufficient， it shall be welded to the fixed thickness， ground and sandblasted， and repair welding shall be adopted where there are cracks， even if the steel pipe with another large opening can be made up at one time.
KThe strength， many mechanical machines are under repeated load， and the whole opportunity is tired in this environment.
GWhere can I find it?Performance index analysis fatigue of square tube the strength， plasticity and hardness discussed above are the indicators of the mechanical properties of metal under static load. In fact，Galvanized pipe_ Galvanized square pipe_ Seamless steel pipe_ Square tube - Wuxi Jiahang many machine parts work under cyclic load， under which fatigue will occur.
nGThe common surface treatment of square pipe includes surface treatment， chemical treatment， shot blasting treatment， manual mechanical treatment and flame treatment. The treated will be separated. ~ Mpa compressed air entrains abrasives， and the nozzle sprays to the steel surface at high speed. The impact and friction of abrasives remove the oxide scale， rust and dirt on the steel surface， and make the steel surface reach a certain roughness.
Production standard classification square tube is divided according to production standard: national standard square tube， British standard square tube American standard square tube， European standard square tube and non-standard square tube.
Performance index analysis of square tube - hardness is an indicator to measure the hardness and softness of metal materials. At present， the hardness method is commonly used to measure the hardness in production. It uses the indenter with fixed geometry to measure the hardness value of the metal material surface tested under fixed load according to the degree of hardness.
Information recommendationmHardness test is to determine the hardness of seamless qb square pipe by slowly pressing a hard indenter on the sample surface according to the specified conditions， and then testing the indentation depth or size.
DAlloy steel: A. low alloy steel (total alloy element content & le; %); b. Medium alloy steel (total alloy element content > ~ %); c. High alloy steel (total alloy element content > %).
before slicing. Highlight: push your hand straight up and down without bending and tremor. Dont know when its down. Take a constant speed and hand power to stabilize it. Dont slice or cut it completely.
xSquare tube saves raw materials: the material rate of cold parts can usually reach more than %. For example the material rate of pin cutting of brand automobile is %， while the material rate when cold is used is increased to %; For another example， after the universal joint bearing sleeve is changed to cold， the material rate is increased from % in the past to%. It can be seen that the use of cold production of mechanical parts can save a lot of steel and non-ferrous metal materials.
xVIt is mainly caused by the fact that the square pipe body has no cover， the covering protection is not ideal， and there is no support， partly due to the excessive number of stacking layers， with large annual rainfall， high air humidity， ponding in the square pipe and the square pipe. The protection shall be: if the bare pipe or pipe needs to be stored for a long time， it shall be protected with an uncovered object from the beginning of storage to avoid rusting， layer aging， edge warping and other phenomena of the square pipe.
Low alloy steel is divided into q Mn， Q， St-， etc.