High carbon, plain and alloy steels

Double tempering is usually necessary after welding the first temper removes retained austenite but converts it to martensite which can be removed only by a second temper. It is an advantage to cool slowly after welding to a temperature as low as possible below the Ms (usually 50-70°C minimum) before reheating for tempering. 

Ms temperatures cah be obtained from the steelmakers literature, from the collections of isothermal transformation data, or from formulae based on composition, as set out below (see Ref. 3). 

For steels containing between 2 and 5%Cr, the following empirical formula is more useful  

For steels containing nominally 12% to 18%Cr (10), with carbon below about 0.3%, the following relationship may be used  

Such steels contain additions of sulphur within the range 0.10- 

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