Generally speaking, DW-exothermic weld (low temperature heat) developed by Sunlight can prevent the production of martensite and Bainite in accordance with the strict requirements of rail, and has passed the key indicators inspection of railindustry, such as metallographical structure, fatigue load and drop hammer test.Due to the physical and chemical characteristics of the rail, Sunlight has developed DW-exothermic weld powder(low temperature heat) , which differs a lot in the formula, requirements, operations compared to traditional cable exothermic welding. DW-exothermic weld powder(low temperature heat) can prevent the production of martenite and bainite during welding, and now is mainly used for rail flow line, rail return line, rail jumper, rail bond(continuous line), and rail cables, etc. Because of its good conductive performance, reliable connection effect, persistent vibration-resistance characteristics, it has been widely applied in the subway, light rail, trams and railway transportation around the whole country in China(such as Chengdu Metro, Chongqing Rail Transit, Shenzhen Metro, Changsha Subway, Hangzhou Metro, Beijing Subway, Xi\'an-Chengdu High-Speed Railway, Beijing-Shanghai High-speed Railway, Chengdu-Kunming Railway). Sunlightweld™ DW-exothermic weld series has passed IEEE837, UL467, IEC62561, CE and RoHS certification. It is a new generation of exothermic welding technology. DW-exothermic weld powder(low temperature heat) has the following characteristics/advantages:
1.Contain no toxic heavy metals such as tin, harmless to personnel or environment.
2.The special formula makes the rail easy to weld.
3.The reaction temperature is low and does not affect the metallographic structure of the rail.
4.The welding reaction is smooth, without irritating smell.
5.Sustances in the formula are not detrimental to welding-spots on rail.
6.The temperature and speed of the combustion during welding have decreased quantitatively.
7.The welding temperature drops slowly in accordance with the predetermined speed.
Weld mold for DW-exothermic weld series:
1. Earnest design: capacity, flow path
2. Precise mold design, accurate tolerance.
3. Meet the special needs of rail welding and ensure joints quality.
Welding joints/connection standard:
1. The transition Resistance in the weld connection of the rail and the cable is less than 30 μ Ω.
2. The welding joint pass the drop hammer test.
3. Tolerate 2 million uninterrupted fatigue loads.
Welding quality of DW-exothermic weld series
1. The reaction temperature of DW series lower than that of conventional/traditional exothermic weld powder.
2. Standard welding temperature control parameters, ensuring the consistency of metallographical structure in rail.
3. The welding reaction is stable and smooth, without intense spraying and harsh noise.
4. The welding joints are smooth in appearance, without penetrating pores.
5. No damage/crack at the welding spot when do the flaw detection test.
6. Can effectively prevent the production of martensite and bainite
Generally speaking, DW-exothermic weld (low temperature heat) developed by Sunlight can prevent the production of martensite and Bainite in accordance with the strict requirements of rail, and has passed the key indicators inspection of railindustry, such as metallographical structure, fatigue load and drop hammer test. 
