(1) Ir-raġunijiet ewlenin għat-toqob tal-arja: hemm sadid, tebgħa taż-żejt, eċċ. Fuq il-wiċċ tal-metall bażi jew tal-metall tal-mili, u l-ammont ta 'toqob tal-arja jiżdied jekk il-virga tal-iwweldjar u l-fluss ma jiġux imnixxfa, għax is-sadid , tebgħa taż-żejt, u l-umdità fil-kisi u l-fluss tal-virga tal-iwweldjar jiddekomponu fil-gass f'temperatura għolja, u jżidu l-kontenut tal-gass fil-metall ta 'temperatura għolja. The welding line energy is too small, and the cooling speed of the molten pool is large, which is not conducive to the escape of gas. Insufficient deoxidation of weld metal will also increase oxygen porosity.

a. Remove the oil stain, rust, water and sundries from the welding wire, working groove and its adjacent surfaces.
b. Vireg u flussi tal-iwweldjar alkalini għandhom jintużaw u mnixxfa sewwa.
Ċ. DC reverse connection and short arc welding shall be adopted.

a. Reduce the content of harmful elements such as sulfur and phosphorus, and weld with materials with low carbon content.
b. Certain alloy elements are added to reduce columnar crystals and segregation. For example, aluminum and iron can refine grains.
Ċ. The weld with shallow penetration shall be used to improve the heat dissipation condition so that the low melting point material floats on the weld surface and does not exist in the weld.
d. Welding specifications shall be reasonably selected, and preheating and afterheating shall be adopted to reduce the cooling rate.
e. Tadotta sekwenza raġonevoli ta 'assemblaġġ biex tnaqqas l-istress tal-iwweldjar.

Miżuri biex tevita xquq mill-ġdid:
a. Pay attention to the strengthening effect of metallurgical elements and their influence on reheat cracks.
b. Reasonably preheat or use afterheat to control the cooling rate.
Ċ. Reduce residual stress to avoid stress concentration.
d. Waqt it-tempra, evita ż-żona tat-temperatura sensittiva ta 'xquq mill-ġdid jew tqassar il-ħin tar-residenza f'din iż-żona tat-temperatura.

a. Low hydrogen type alkaline welding rod shall be used, dried strictly, stored at 100-150 ℃, and used when taking.
b. It-temperatura ta 'tisħin minn qabel għandha tiżdied, il-miżuri ta' wara t-tisħin għandhom jittieħdu, u t-temperatura ta 'interpass m'għandhiex tkun inqas mit-temperatura ta' tisħin minn qabel. The reasonable welding specification shall be selected to avoid brittle and hard structures in the weld.
Ċ. Select reasonable welding sequence to reduce welding deformation and welding stress.
d. Conduct hydrogen elimination heat treatment in time after welding