I anyone familiar with "CD-4"or "CD4 MCU", ASTM A-743? My pump suppler offered in-stock delivery of a spare pump body made of this material that is now their standard. My original was supposed to be 316 SS, but it was a cast part, not wrought. I'm looking for sources of info on this newer material.

Andy CD-4 or CD 4 MCu is a semi asusteniti duplex stainless steel material . This was used by me way back in 1971/1972 in a fertilizer plant for high capacity Cooling Water Pump impellers (Double Suction Impeller) which used to get eroded - corroded whre fine suspended solids in cooling water used to erode / corrode the impellers quite often. The orignal Bronze impeller used to perofrom very poorly. We developed this CD 4 / CD M Cu cast impeller with a specific foundry in India with specific hardness to ward off the problem. To my knowledge, we have not changed the impeller for more than 18-20 years after this replacement was done in 1972. We used these double suction impellers in all our Cooling water impellers (as Import substitution for original U.S supplied pump impellers in a fertilizer plant). This import substituite material in CD 4 / CD 4 M Cu lasted to my knowledge for more than 20 years without any problem in cooling water service in a fertilizer plant . We developed this in India in 1971. Semi austenitic duplex stainless steel material like this CD 4 / CD M Cu would be both abrasion / erosion / corrosion resistant in cooling water service where fine suspended particles used to erode Bronze impellers. I do not know the specific use for which your pump supplier is offering you this material. If he had offered for Cooling water service (which most probably would have been the case), specify the hardness in the range of Rc 40-44 (Rockwell C Scale : 40-44) to get good hardenss / impact resistance from abrasion resistance / erosion resistance in cooling water service Trust this infor mation will be helpful. C.V.Srinivasan Tech Director Nishi Engineers Pvt Ltd Chennai 20 India March 26, 2004 If you need any specific information please e-mail: nishi@vsnl.com