In this research, the welding experiment was carried out with both the steel materials (SS400+SS400, SUS304+SUS304) and the different steel materials (SS400+ SUS304), where SS400 is a general structural rolled steel material and SUS304 is a cold strip stainless steel sheet. The average of yield point of a SS400 experimental piece was the most highest point with 2015.54 N/m2. Although welding defects were not found with the naked eye, it was sure that there were some wilding defects because there were no stress against load through experiments. The rate of yield point of experimental piece A, experimental piece B and experimental piece C was respectively 1.7mm, 1.3mm and 2.6mm. The rate of breakdown was respectively 39.77mm, 17.97mm and 2.6mm. So considering price and efficiency with use condition is very important. SS400 and SUS304 will be profited from considering price and mechanical property with use condition.

In order to develop the SUS304L housing by powder metallurgy for an optical device useful for the FTTH communication system, the optimum compacting pressure and sintering temperature were investigated using granulated powder as the material to satisfy high air-tightness and high laser-weldability. Then the laser-welding test of specimen made under the optimum condition was carried out to observe welding sputters.

정변위 인장시험기를 사용하여 SUS 304강 용접열 영향부의 여러 가지 염화 마그네슘용액 중에서의 SCC 발생 특성을 연구한 결과 다음과 같은 결론을 얻었다. 1) SCC 발생 잠복기간은 초기 응력강도계수 K 하(Ii) 값은 낮게 함으로써 크게 지연된다. 2) 비등 염화 마그네슘 용액 중에서의 SCC 발생은 부하와 Cl 이온의 농도에 의한 부동태 피막의 파손에 기인된다. 3) SUS 304 강 용접열 영향부의 SCC 발생 감수성은 높은 농도의 염화 마그네슘 용액일수록 온도를 낮게 함으로써 둔화된다.