ASTM A333 Grade 6 is among the most generally used low temperature steel pipelines, its minimal solution temperature level is -70 ℃, generally in normalizing or normalizing and also toughening up problem. ASTM A333-GR6 steel has reduced carbon web content, exceptional low temperature durability, plasticity and welding performance, and also small quenching and chilly splitting propensity. The reduced temperature level wldsteel co.,ltd toughness, particularly the capability to avoid brittle failing from taking place and also expanding at low temperature level, is one of the most essential variable impacting its welding efficiency.
Typical welding techniques for low temperature steel include arc welding, submerged arc welding, argon arc welding and so forth. MIG welding is the most commonly utilized automatic or semi-automatic welding method in low temperature steel welding. Its welding heat input is 23-40kJ/ cm. According to the setting of droplet transfer, it can be divided into brief circuit transition procedure (reduced heat input), jet change procedure (high heat input) and also pulse jet shift procedure (the highest possible warmth input). Short-circuit shift MIG welding may have the issue of inadequate melting depth or bad combination. In order to make the arc much more concentrated and get sufficient infiltration deepness, CO2 or O2 can be added to the pure argon securing gas. The particular quantity of addition must be identified according to the steel grades.
Welding materials (including electrode, wire as well as flux, etc.) shall be selected according to the welding technique adopted, joint type as well as groove form and needs. For low temperature level steel, one of the most vital thing to pay attention to is to make the weld steel have sufficient reduced temperature level sturdiness to match the base metal as well as lessen the hydrogen diffused in it. Normally, ER80S-Ni1 argon arc welding wire is utilized.
In welding, I-Shape port is made use of for pipes with diameter less than 76.2 mm, and full argon arc welding is executed. For the V-groove of pipeline with diameter higher than 76.2 mm, argon arc support and multi-layer filling are adopted, or complete argon arc welding That's relies on certain pipe diameter as well as pipeline wall surface thickness.
( 1) Preheating prior to welding.
When the ambient temperature level is less than 5 ℃, the steel pipeline should be preheated, and also the preheating temperature level is 100 ~ 150 ℃. The pre-heating range is 100 mm on both sides of the weld; Heated by oxyacetylene flame (neutral flame), the temperature was gauged equally at a range of 50 ~ 100 mm from the weld center for far better temperature control.
( 2) Postweld warmth treatment
In order to improve the notch strength of cryogenic steels, many steel tubes have actually been toughened up and also toughened up, so that post-weld heat therapy is not normally needed for cryogenic steels, besides thicker weldments or in serious problems.
If special components require to be warm dealt with after welding, according to the home heating price, constant temperature time and cooling rate of the warm therapy after welding, the list below arrangements need to be purely applied:
When the temperature increases above 400 ℃, the heating rate shall not surpass 205 × 25/ δ ℃/ h, as well as will not exceed 330 ℃/ h. Constant temperature time should be 1 h per 25 mm density constant temperature, and will not be less than 15 minutes, maximum and also minimum temperature during the temperature ought to be less than 65 ℃. After consistent temperature, the cooling price shall not be greater than 65 × 25/ δ ℃/ h, and shall not be above 260 ℃/ h, and also natural cooling can be done listed below 400 ℃.
Tips for welding ASTM A333 Grade 6 tubing
( 1) Preheat strictly according to the arrangements, control the temperature in between the layers, the temperature level in between the layers is controlled at 100 ~ 200 ℃.
( 2) Strictly control line power, small present, reduced voltage, fast welding.
( 3) complete infiltration process must be adopted, and also the procedure setting of short arc and no swing.
( 4) The recurring height of the weld is 0 ~ 2mm, and the width of each side of the weld is less than 2mm.
( 5) Nondestructive testing can be performed at least 24 hrs after the appearance inspection of the weld is qualified.