| 摘要: | 電弧熔接雖使用相同或相近的溶接條與被溶接母材之鋼料，但因熔接區域受「突然間産生的高溫電弧溶接熱」之影響，溶接區域附近的「熱影響區」産生不同大小亦不均勻顆粒的金相組織，或許同大小而均勻之顆粒，其受熱長短，保持熱量的時間不同或冷却速度之不同，亦會發生熱影響區域不同之硬度、強度以及其機械性質的連續變化，以往從未對熔接部位非均勻顆粒熱影響區，以非均質之立場作一系列而完整的熔接法試驗、材料試驗、列表比較，以探討最完美的熔接法。
本文係探討「同厚度熱浸鍍鋅鋼板熔道的不均勻顆粒熱影響區」之最完美電弧接法，亦係利用Φ1.2mm電極線、Φ3.2mm各種被覆熔接條，先分成手動及全自動，然後以五種不同型式之被覆熔條，四種不同保護氣體，再以不同電流值，不同熔接條傾斜走行角度，不同熔接行進速度，作電弧熔接試驗，其次分別測定「鍍鋅與不鍍鋅鋼板用各種不同熔接法所得熔接道」之機械性質，並且列表比較，分析以探討最完美的電弧熔接法，以提供最完整的資料，給予初次無電弧熔接經驗者作最有價值這參考及選擇。
Two-type ob weed joints were investigated: joint A consisting of 0.04% C Carbon Steel to Carbon Steel, 1.2mm to 1.2mm thickness butt goint, and joint B consisting of 0.038% C Carbon steel to Carbon Steel 3.2mm to 3.2mm thickness butt joint. The chamical compositions of thesesmaterials are listed in Table 2-3-1.
In so far as are characteristics and transition current were uncerned Co2, CO2+O2, Ar+CO2 and Ar+O2 shielded-gas metal-arc welding yielded optimum spray transfer behavior.
Knowledge and control of the Operating Variables in shielded-gas metal arc welding are essential if high production rates and welds of good quality are to be obtained unsistently. These variables, in the approximate order of their importance are: 1. welding amperage 2. welding voltage 3. welding speed.
Some application rules to remenber concerning welding amperage are 1. in creases penetration and melting arc 2. Excessively high amperage produces a digging arc, an under cut; or a high narrow bead. 3. Excessively low amperage produces an unstable arc.
Increasing the arc voltage with constant amperage and travel speed will: 1. Produce a flatter and wider bead 2. Increase flux consumption. 3. Tend to reduce purosity caused by rust or scale on steel.
4. Help bridge excessive root opening when fit-up is poor. 5. Improve pick up of alloying elements from the flux when they are present. Travel speed with any combination of welding amperage and voltage, the effects of changing the travel speed conform to a general pattern, If the traved speed is increased 1. Powwer or heat input per unit length of weld is decreased 2. Less filler metal is applied per unit length of weld and consequently less weld reinforcement results. 3. Penetration decreases, thus, the weld becomes smaller.
The experiment on gas metal-arc weeding of galvanized steel plate was carried out by manual welding with various types of electrodes and automatic gas-shielded metal-arc welding. The test results obtained are summarized as follows:
1. Amount of fume of the galvannized steel plates about 2 times as much as that of the non galvanized steel plate was in the case of coated electrodes and it was several times with gas-shielded metal-arc welding, especially when it was the highest CO2 shieldingas.
2. Good-appearance beads and sound welded joints were obtained by ilmenite, lime-titania and high titanium oxide type electrodes. Appearance of beads by high cellulose and low hydrogen type electrodes were good, but blowholes or slag inclusion in welded metals were observed by X-ray.
On the other hand, good apperance and sound welded joint were obtained by CO2, CO2+O2, Ar+CO2, Ar+O2 shielded-gas metal-arc welding.
3. Sound weldedjoints were satisfactory in tensile strength and ductility in comparison with the base metals. Zinc content of weld metal showed no detrimental effect on its mechanical properties.
4. Zinc content of weld metal was the highest by lowhydrogen type electrode and the lowest by high cellulose type electrode. Shielding gas and the lowest by Ar+O2 shielding gas in the case of high current, high voltage condition and short circuit transfer condition, respectively.
And so, it seems that the arc welding of galvanized steel plate has no difficulty with the precaution of ventilation. |
