Welding Maraging Steel

In the initial stage of rocket development ISRO was using a quenched and tempered high strength steel designated as 15CdV6. Demand for more powerful rockets necessitated to identify a material which has higher strength and better weldability than 15CdV6. The material identified was a high strength steel Maraging 250 steel. Mishra Dhatu Nigam (Midhani), which is a factory which is set up to manufacture special special steels and alloys agreed to supply Maraging 250 steel. But there was a hitch. No body had welded maraging steel in India. Midhani was asked by ISRO to supply not only the material but also the welding technology. Midhani looked up to R&D of BHPV to develop the welding technology by placing a developmental contract. The development was a tough assignment. The developed technology must not only meet the strength requirements but also meet the fracture toughness specified by ISRO, Hence we had to optimise the welding procedure. But it must be repeatable and produce consistence results. How we went about developing the welding technology is the essence of this blog which will follow.