In report 1, the manual arc welding of austenitic manganese steel to high carbon steel was studied, the main characteristic of which was to butter, before joining, the groove face of high carbon steel with austenitic covered electrode.
This paper describes the results of some experiments on welding of the above two dissimilar metals by gas shielded arc welding process.
To select appropriate welding wire and welding conditions for buttering, single bead weld test and FISCO cracking test were made using high carbon steel as base metal, five austenitic welding wire as electrode, and CO₂, CO₂-A, A or N₂ as shielding gas.
16 Mn-16 Cr and 25 Cr-20 Ni welding wire are available for buttering electrode and CO₂-A for shielding gas from the viewpoints of weld metal hardness, microstructure, weld defects and crack susceptibility of weld metal.
Carbon steel rail and austenitic manganese steel rail (50 PS type) were then welded together automatically by gas shielded arc welding process: The groove face of the former was buttered vertically with above-mentioned wires and shielding gas and rail welding apparatus, which could be used not only for rail joining by welding but also for buttering with some modifications. An austenitic manganese steel rail was welded to the buttered carbon steel rail with I-groove and almost the same welding conditions as in the case of gas shielded arc welding of austenitic manganese steel rails investigated previously by the authors. The values of maximum load and deflection in bending tests of welded rails were 75-85 t and 56-84 mm with head-up (span 1 m, load applied at mid span) and they are almost equal to the welds by manual arc welding with V-or I-groove joint.
Welding takes about 11 minutes for buttering and 7.5 minutes for joining.

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A prototype gas shielded arc welding apparatus for continuous automatic welding of austenitic manganese steel rail was built. This apparatus consists of the main assembly including abed, copper blocks and a torch-moving mechanism, the special torch, the controller for controlling the torch movement, the operating panel and the ordinary gas shielded arc welder. It is provided with a device for water-cooling the heat affected zone (HAZ) of base metal.
Using the above-mentioned apparatus, austenitic manganese steel rails were welded by gas shielded arc welding process. The materials and welding conditions adopted are as follows: Base metal; 50 kg/m PS type, Wire; 16 Mn-16 Cr, Dia.; 1.6 mm, Shielding gas; CO₂-A (50-50%), Joint type; I-groove, Gap; about 16 mm, Arc voltage; 35V, Current; 475A (average), Procedure; automatic and continuous, Forced cooling of base metal; HAZ water-coiled during welding, the whole weld water-cooled after welding.
The bending test results on welded rails show that the values of maximum load and deflection are fairly good-76-83 t and 61-103 mm with head up and 73-77 t and 71-77 mm with head down respectively (span 1 m, load applied at midspan). Fracture invariably propagates through the HAZ within 15 mm of fusion line. In certain areas of HAZ, the impact values. are considerably inferior to those of base metal, but except in the cases where casting defects are present, they exceed 10 kg-m/cm² (2U, 20°C), with considerable toughness retained.
Weld metal is almost free from such welding defects as cracks or blow-holes. Local high-temperature cracks may be observed in the HAZ.
Presence of such cracks seems to be practically harmless in general use but they should be minimized in welded rail joint.
Welding takes about 6 minutes, which is by far shorter than 4.5 hours needed for manual arc welding of Vee-groove joint.

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This paper describes the grinding characteristics on high manganese steels (Mn steels) which are austenite type. The grinding tests were performed in order to estimate these grindability by measuring the radial grinding wheel wear or the grinding force and observing the working surface of grinding wheels. The results were compared with those of austenitic stainless steel which has much similarities to high Mn steels in the material properties. The main conclusions are summarized as follows : (1) In grinding of high Mn steels by conventional or CBN grinding wheels, glazing of the cutting edges due to attrition wear is clearly recognized in the former wheel but not in the latter wheels. (2) The grinding wheel wears in the CBN grinding wheels are remarkably smaller than in the conventional wheels. (3) Because of the loading of grinding wheel, grinding wheel wear on austenitic stainless steel is remarkably greater than that on the high Mn steels.

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The welding of austenitic manganese steel to high carbon steel has been thought to be very difficult due to the difference of their metallurgical properties and others. The authors paid special attention to the procdeure to join them by manual arc welding after buttering the groove face of carbon steel. Various fundamental experiments were performed to select proper electrodes for buttering and joining, and welding conditions, though mention here is given mainly of the buttering electrode selection tests- 1) Hardness test and microscopic inspection of weld metal, 2) Angle-expanding type cracking test of weld metal and, 3) Impact test of weld zone.
Based on the results obtained, austenitic manganese steel rail and carbon steel rail (high carbon steel) were welded together, and the welded rails were subjected to bending test, drop-weight test and so forth. The results show that considerably reliable welds are obtained if they are welded together by the following methods: 1) Austenitic manganese steel which has good weldability and no casting defects is used. 2) The welding groove is finished to V or X and arc welding process is executed in flat position. 3) The vicinity of the groove of carbon steel is preheated to 300-400°C, then two layers with 25Cr-2ONi or 25Cr-12Ni type electrodes or one more layer with 16Mn-16Cr type electrodes are buttered over the groove face. 4) The manganese steel rail and the buttered carbon steel rail are welded together with 16Mn-16Cr electrodes. Craters are peened after each pass followed by forcible cooling of the weld zone. 5) The impurities contained such as phosphorus should be as low as possible in the electrodes and the electrodes should give weld metals of very low crack susceptibility. 6) The postheating which is usually adopted for the welding of high carbon steel is not performed.
The final object of this study is to establish the prodceure to weld austenitic manganes steel crossing to carbon steel rail and the welds are now under field test.

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In previous report, various properties of weld metals with 16 Mn-16 Cr welding wire were investigated, which were deposited automatically by gas shielded arc welding process.
The automatic welding being characterized by large heat input, the weld heat-affected zone (HAZ) extends over a wide area and, in the case of austenitic manganese steel, the embrittlement of weld HAZ is likely to aggravate on account of carbide precipitation.
The following experiments, in this study, were made to reveal the deterioration of toughness as a part of the study on gas shielded arc welding.
The thermal cycles in various parts of the weld were measured in single bead welding of austenitic manganese steel plates and continuous automatic welding (electrogas welding) of austenitic manganese steel rails. Based on the data obtained 15 simple thermal cycles (5 peak temperatures ×3 thermal cycle speeds) were selected, which were similar to those produced in actual weld. Austenitic manganese steel specimens were subjected to the above thermal cycles reproduced by synthetic thermal cycle apparatus, and to impact test as well as microscopic inspection.
Deterioration of toughness in synthetic HAZ takes place around 650°C of peak temperature and it becomes heavy at low speed of thermal cycle. In that case, precipitations of carbides appear at intercrystalline boundaries.
At over 1300°C of peak temperature, the toughness of synthetic HAZ decreases remarkably regardless of the speed of thermal cycle; this is due to the presence of intercrystalline cracks or cavities caused through heating.
The toughness of synthetic HAZ at 650°C of peak temperature tends to be somewhat low when the impact test temperature is low (-40-20°C).
Finally the decrease of toughness in weld HAZ was discussed from the standpoint of carbide-preciptation temperature-range in thermal cycles measured. Mention was also made of high temperature cracks observed.

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The present study investigates the influence of three-dimensional tool geometry upon the cutting mechanism of a 18%Mn-5%Cr steel with a P 20 carbide tool, where the computer simulation method proposed in the previous paper has been employed. The three-dimensional simulation has revealed that the physical background of empirical knowledge such that a larger corner radius is recommended for difficult-to-cut materials for large work-hardening and low thermal conductivity; the increase of the radius causes a large chip-flow angle and small undeformed and deformed chip thicknesses at the corner, leading to the decrease in the deformation and the drop of temperature. As a result, not only wear at the corner but also the influence into the finished surface is lessened. Experiments have validated the simulation results: both predicted and measured cutting forces, chip geometry, tool temperature and tool wear accord well with each other.

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