Berikut ini adalah beberpa pertanyyan yang sering muncul tnetang masalah seputar welding.
1. Apakah maksud dari H4R dari consumable SMAW E7018 H4R?
H4R is an optional supplementary designator, as defined in AWS A5.1-91 (Specification for shielded metal arc welding electrodes). Basically, the number after the “H” tells you the hydrogen level and the “R” means it’s moisture resistant.
“H4” identifies electrodes meeting the requirements of 4ml average diffusible hydrogen content in 100g of deposited weld metal when tested in the “as-received” condition.
“R” identifies electrodes passing the absorbed moisture test after exposure to an environment of 80ºF(26.7ºC) and 80% relative humidity for a period of not less than 9 hours.
The H4R suffix is basically just additional information printed on the rod, and does not necessarily mean a change in an electrode previously marked E7018.
2. Kenapa Masalah Hydrogen sangat penting dalam Welding?
Hydrogen contributes to delayed weld and/or heat affected zone cracking. Hydrogen combined with high residual stresses and crack-sensitive steel may result in cracking hours or days after the welding has been completed.
High strength steels, thick sections, and heavily restrained parts are more susceptible to hydrogen cracking. On these materials, we recommend using a low hydrogen process and consumable, and following proper preheat, interpass, and postheat procedures. Also, it is important to keep the weld joint free of oil, rust, paint, and moisture as they are sources of hydrogen.
3. Consumable Jenis apa yang cocok untuk Cast Iron welding?
Cast irons are alloys which typically have over 2% carbon plus 1-3% silicon and are difficult to weld. Electrodes with a high percentage of nickel are commonly used to repair cast iron. Nickel is very ductile, making it a good choice to weld on cast iron, which is very brittle. Softweld® 99Ni and Softweld® 55Ni are the Lincoln Electric® electrodes designed for welding cast iron.
4. Kenapa hasil Impact Test yang didapat lebih rendah dari yang disebutkan dalam certificate?
The test results on our Certificate of Conformance were obtained from welding an AWS filler metal test plate. Any change in welding procedure will affect Charpy impact values. Below are common practices for welding test plates when Charpy impact specimens are required:
1.Controlled heat input
2.Controlled preheat and interpass temperature
3.Even number of passes per layer
4.Build-up cap pass to maximum allowed in specification