1952 Volume 21 Issue 2 Pages 47-58
There are many practical applications in which austenitic stainless steel electrodes are utilized in welding of various plain carbon and alloy steels (low and high). Since the above joining is also considered as a so-called disimilar-metal welding from the standpoint of chemical composition, it is naturally expected that penetration ratio of base metal to the austenitic stainless steel weld metal, in other words, the degree of dilution of austenitic stainless steel weld metal by base metal may depend upon several welding conditions, and the mechanical and chemical properties may accordingly he different, too. The present researches were conducted in order to disclose, systematically and fundamentally, the relation between the above properties of austenitic stainless steel weld metal and several welding conditions.
In this report, relations between polarity and welding current, amount of penetration and penetration ratio of base metal to the austenitic stainless steel weld metal, hardness of austenitic weld metal and microstructure, etc., in each single bead which was deposited on four kinds of carbon steel plates with plain 18-8 austenitic stainless steel electrode consisting of commercial 18-8 austenitic stainless steel core wire of 4mm. in diameter and suitable coating, were studied. D. C. (straight and reverse polarity) and a. c. were used. Welding speed and thickness of base metal were constant, 203mm/min and 10 mm respectively. The results obtained are as follows :
(1) In either d. c. (straight and reverse polarity) or a. c., the amount of penetration and penetration ratio, . etc., have a tendency to increase linearly as welding current increases. And also in this case, the above penetration ratio increases from about 20 to 60 percent as welding current increases from 95 to 175 amperes.
(2) Penetration ratio has a little, tendency to increase, as carbon content of base metal increases.
(3) Penetration ratio with a. c. is smaller than with d. c., in the same welding current value. (4) There is only a little difference between penetration ratio in d. c. straight polarity and that' in d. c. reverse polarity. In this experiment, however, penetration ratio in d. c. straight polarity is larger than that in d. c. reverse polarity for the range of lower welding current value. On the contrary, penetration ratio in d. c. reverse polarity is larger than in d. c. straight polarity for the range ot higher welding current value.
(5) Vickers hardness of austenitic stainless steel weld metal is comparatively high. And Vickers hardness of austenitic weld metal containing high carbon base metal is lower for the range of smaller penetration ratio, but higher for the iange of larger penetration ratio, than that of the metal containing low carbon base metal.
(6) Micro-hardness at the side of austenitic stainless steel weld metal of the vicinity of weld fusion line increases linearly as welding current increases, and is higher in the weld metal containing high carbon base metal than in the one containing, low carbon base metal. Consequently, the tendency of the above micro-hardness change is clearly different from that of Vickers hardness change.
(7) Both maximum Vickers hardness of heat-affected zone and micro-harness of the vicinity of weld fusion line of that same zone in base metal, tend to decrease as welding current increases.
