How to check coefficient of expansion of precision steel pipe

Check the method can be used in the annealing furnace soapy water to wipe each joint crevice, to see whether to run gas; places where gas is most likely to run into the annealing furnace tube and place the tube in place, this place seals are particularly vulnerable to wear and tear, Always check often change. Presented before the roll forming of precision steel pretreatment process scheme; analysis of the normalizing temperature, holding time and cooling influence of the raw material tube microstructure and mechanical properties; determining the conventional normalizing process precision steel tubes: heating temperature (890 ± 10) ℃, air cooling after holding 6min interspersed. The conventional normalizing process can be completely eliminated precision steel Widmanstaten to match the yield strength and tensile strength is more reasonable yield ratio σS / bσ≤0.78, elongation 5δ≥30%, and greatly improved cold formability avoid cold-formed crack. The expansion coefficient can be expressed by volume or length is usually expressed in terms of length.

Precision steel pipe cooling after welding residual stress

Density is the mass density of the material per unit volume of the substance, the unit is kg / m3 or 1b / in3. Tensile residual stress is mainly from tensile residual stress generated in the device during the welding process. At present, widely used in engineering annealing treatment to eliminate residual stress after welding cooling, and cooling after welding residual stress is an important process, this approach is a waste of energy and easy to have a greater welding residual stress. Post weld heat treatment is a new technology to eliminate residual stress. Before welding precision steel pipe is preheated to a temperature of heat treatment and welding process weldment continued heating to maintain this temperature, the use of welding is completed cotton insulation be allowed to cool slowly. Quenching the steel pipe to increase the strength and hardness, but to reduce their plasticity. Quench hardening agent commonly used in water, oil, salt alkali solution, and the like. Will have tempered precision steel hardened precision steel re-heated to a certain temperature, and then some method of cooling known as tempering. Its purpose is to eliminate the internal stress generated by quenching to reduce the hardness and brittleness, in order to obtain the desired mechanical properties. Tempering points high-temperature tempering, tempering, and low temperature tempering are three categories. Multi-quenching tempering, normalizing is used in conjunction. After quenching and tempering quenching method is called quenching.