This invention relates to a method of manufacturing a martensitic
stainless steel.The method comprises the following steps (a) to (c): (a)
preparing a steel having a chemical composition consisting of, by mass %,
C: 0.003 to 0.050%, Si: 0.05 to 1.00%, Mn: 0.10 to 1.50%, Cr: 10.5 to
14.0%, Ni: 1.5 to 7.0%, V: 0.02 to 0.20%, N: 0.003 to 0.070%, Ti: not
more than 0.300% and the balance Fe and impurities, and P and S among
impurities are not more than 0.035% and not more than 0.010%
respectively, and that it also satisfies the following equation:
([Ti]-3.4.times.[N])/[C]>4.5 wherein [C], [N] and [Ti] mean the
content (mass %) of C, N and Ti, respectively, (b) heating the steel at a
temperature between 850 and 950.degree. C., (c) quenching the steel, and
(d) tempering the steel at a temperature between Ac1-35.degree. C. and
Ac1+35.degree. C. and in a condition of not more than 0.5 of the value of
variation .DELTA.LMP1 in the softening characteristics LMP1, which is
defined by the following equation:
LMP1=T.times.(20+1.7.times.log(t)).times.10.sup.-3 wherein T is a
tempering temperature (K), and t is a tempering time (hour).The steel
could further contain 0.2 to 0.3 % of Mo.